Zachary, Hope this addresses any concerns regarding the viability of concrete pavers and their use with heavy vehicular loads. Sincerely, Mike Midyett

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1 From: To: Cc: Subject: Date: Attachments: Mike Midyett Kristen Tischler; Jan Sillers Use of pavers in vehicular applications Tuesday, October 18, 216 3:25:5 PM TechSpec4-Traffic.pdf Fire Truck.jpg Copy of Fort Carson Pavers jpg Copy of Fort Carson Pavers jpg icpifactsheet_municipal_39211.pdf NREL Loading.docx Zachary, Attached is the Technical Specification #4 for pavers in vehicular applications. Structural Design of Interlocking Concrete Pavement for Roads and Parking Lots addresses the design parameters of concrete unit pavers and the variety of loads which interlocking concrete pavers can meet. As you reference an 8, # vehicle weight, this is equal to the legal weight limit of a tractor trailer operating on an interstate highway. Pavestone facilities in Denver and Colorado Springs handle s of these deliveries on a daily basis, with loads tracking over concrete pavers at both facilities. Similar to typical asphalt roadways, provided the subgrade, sub-base and base have been adequately designed, concrete pavers will easily meet the design requirements of a fire truck. In addition, I ve included a photo of a fire truck at our Denver Pavestone facility, a 75 Ton M1A1 main battle at Fort Carson which is trafficked over a 3-1/8 thick concrete paver (the rubber marks was from the tank treads), municipal fact sheet with a fire truck on a paver driveway and finally, photos of a bus and fire truck on paving stones at the National Renewable Energy Lab in Golden. Hope this addresses any concerns regarding the viability of concrete pavers and their use with heavy vehicular loads. Sincerely, Mike Midyett Pavestone,LLC VP-Mountain Region (M) mike.midyett@pavestone.com

2 PAVE ATLANTA, GA: (77) AUSTIN/SAN ANTONIO, TX: (512) BOSTON, MA: (8) CHARLOTTE, NC: (74) CINCINNATI, OH: (513) COLORADO SPRINGS, CO: (719) DALLAS/FT. WORTH, TX: (817) DENVER, CO: (33) HAGERSTOWN, MD: (24) HOUSTON,TX: (281) KANSAS CITY, MO: (816) LAS VEGAS, NV: (72) NEW ORLEANS, LA: (985) PHOENIX,AZ: (62) CAPE GIRARDEAU, MO: (573) SACRAMENTO/WINTERS, CA: (53) SECTION INTERLOCKING CONCRETE PAVERS (Section 2518) Note: This guide specification for concrete paver applications in the U.S. for concrete pavers and bedding sand over a compacted aggregate base for pedestrian and vehicular applications. The text must be edited to suit specific project requirements. This Section includes the term "Architect." Edit this term as necessary to identify the design professional in the General Conditions of the Contract. PART 1 GENERAL 1.1 SUMMARY A. Section Includes: 1. Interlocking Concrete Paver Units (manually installed). 2. Bedding and Joint Sand. 3. Edge Restraints. 4. {Cleaner, Sealers, and Joint sand stabilizers]. B. Related Sections: 1. Section: [ ]-Curbs and Drains. 2. Section: [ ]-Aggregate. 3. Section: [ ]-Cement Treated. 4. Section: [ ]-Asphalt Treated. 5. Section: [ ]-Pavements, Asphalt and Concrete. 6. Section: [ ]-Roofing Materials. 7. Section: [ ]-Geotextiles. Note: Pavements subject to vehicles should be designed in consultation with a qualified civil engineer, in accordance with established pavement design procedures and in accordance with the ICPI Tech Spec technical bulletins. Use the current year reference. 1.2 REFERENCES A. American Society for Testing and Materials (ASTM): 1. ASTM C 33, Standard Specification for Concrete Aggregates. 2. C 67, Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile, Section 8, Freezing and Thawing. 3. ASTM C 136, Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates. 4. ASTM C 14, Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units. 5. ASTM C 144, Standard Specification for Aggregate for Masonry Mortar. 6. ASTM C 936, Standard Specification for Solid Concrete Interlocking Paving Units. 7. ASTM C 979, Standard Specification for Pigments for Integrally Colored Concrete. 8. ASTM D 698, Standard Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12, ft-lbf/ft 3 (6 kn-m/m 3 )). 9. ASTM D 1557, Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort (56, ft-lbf/ft 3 (2,7 kn-m/m 3 )). 1. ASTM C 1645, Standard Test Method for Freeze-thaw and De-icing Durability of Solid Concrete Interlocking Paving Units. 11. ASTM D 294, Specification for Graded Aggregate Material for s or s for Highways or Airports. B. Interlocking Concrete Pavement Institute (ICPI): 1. ICPI Tech Spec Technical Bulletins Pavestone Paver Specification Pg 1 of 7 2/9

3 1.3 SUBMITTALS A. In accordance with Conditions of the Contract and Division 1 Submittal Procedures Section. B. Manufacturer s drawings and details: Indicate perimeter conditions, relationship to adjoining materials and assemblies, [expansion and control joints,] concrete paver [layout,] [patterns,] [color arrangement,] installation [and setting] details. C. Sieve analysis per ASTM C 136 for grading of bedding and joint sand. D. Concrete pavers: 1. [Four] representative full-size samples of each paver type, thickness, color, finish that indicate the range of color variation and texture expected in the finished installation. Color(s) selected by [Architect] [Engineer] [Landscape Architect] [Owner] from manufacturer s available colors. 2. Accepted samples become the standard of acceptance for the work. 3. Test results from an independent testing laboratory for compliance of concrete pavers with ASTM C Manufacturer s catalog product data, installation instructions, and material safety data sheets for the safe handling of the specified materials and products. E. Paver Installation Subcontractor: 1. A copy of Subcontractor s current certificate from the Interlocking Concrete Pavement Institute Concrete Paver Installer Certification program. 2. Job references from projects of a similar size and complexity. Provide Owner/Client/General Contractor names, postal address, phone, fax, and address. 1.4 QUALITY ASSURANCE A. Paving Subcontractor Qualifications: 1. Utilize an installer having successfully completed concrete paver installation similar in design, material, and extent indicated on this project. 2. Utilize an installer holding a current certificate from the Interlocking Concrete Pavement Institute Concrete Paver Installer Certification program. B. Regulatory Requirements and Approvals: [Specify applicable licensing, bonding or other requirements of regulatory agencies.]. C. Mock-Ups: 1. Install a 7 ft x 7 ft (2 x 2 m) paver area. 2. Use this area to determine surcharge of the bedding sand layer, joint sizes, lines, laying pattern(s), color(s) and texture of the job. 3. This area will be used as the standard by which the work will be judged. 4. Subject to acceptance by owner, mock-up may be retained as part of finished work. 5. If mock-up is not retained, remove and properly dispose of mock-up. 1.5 DELIVERY, STORAGE & HANDLING A. General: Comply with Division 1 Product Requirement Section. B. Comply with manufacturer s ordering instructions and lead-time requirements to avoid construction delays. C. Delivery: Deliver materials in manufacturer s original, unopened, undamaged containers packaging with identification labels intact. 1. Coordinate delivery and paving schedule to minimize interference with normal use of buildings adjacent to paving. 2. Deliver concrete pavers to the site in steel banded, plastic banded or plastic wrapped packaging capable of transfer by forklift or clamp lift. 3. Unload pavers at job site in such a manner that no damage occurs to the product. D. Storage and Protection: Store materials protected such that they are kept free from mud, dirt, and other foreign materials. [Store concrete paver cleaners and sealers per manufacturer s instructions.] 1. Cover bedding sand and joint sand with waterproof covering if needed to prevent exposure to rainfall or removal by wind. Secure the covering in place. Pavestone Paver Specification Pg 2 of 7 2/9

4 1.6 PROJECT/SITE CONDITIONS A. Environmental Requirements: 1. Do not install sand or pavers during heavy rain or snowfall. 2. Do not install sand and pavers over frozen base materials. 3. Do not install frozen sand or saturated sand. 4. Do not install concrete pavers on frozen or saturated sand. 1.7 MAINTENANCE A. Extra Materials: Provide [Specify area] [Specify percentage.] additional material for use by owner for maintenance and repair. B. Pavers shall be from the same production run as installed materials. PART 2 PRODUCTS 2.1 INTERLOCKING CONCRETE PAVERS A. Manufacturer: Pavestone Company Contact: [Specify Pavestone contact and phone number information.]. B. Interlocking Concrete Pavers: 1. Paver Type: [Specify name of product group, family, series, etc.]. a. Material Standard: Comply with material standards set forth in ASTM C 936. b. Color [and finish]: [Specify color.] [Specify finish]. c. Color Pigment Material Standard: Comply with ASTM C 979. Note: Concrete pavers may have spacer bars on each unit. Spacer bars are recommended for mechanically installed pavers and for those in heavy vehicular traffic. Manually installed pavers may be installed with or without spacer bars. Verify with manufacturers that overall dimensions do not include spacer bars. d. Size: [Specify.] inches [({Specify.}mm)] x [Specify.] inches [({Specify}mm)] x [Specify.] inches [({Specify.} mm)] thick. Note: If 3 1/8 in. (8 mm) thick pavers are specified, the ASTM C 936 Section 6 Sampling and Testing 6.2 states to Sample and test units in accordance with Test Methods C 14, except as required in 5.5. Modify the ASTM C 14 - Paver Annex A4 - The test specimens shall be 6 ± 3 mm thick and, if necessary, cut to a specimen size having a Height/Thickness [H/T] aspect ratio of.6 ±.1. e. Average Compressive Strength (C14): 8 psi (55 MPa) with non individual unit under 7 psi ( MPa) per ASTM C 14. f. Average Water Absorption (ASTM C 14): 5% with no unit greater than 7%. g. Freeze/Thaw Resistance (ASTM C 1645): 25 freeze-thaw cycles with no greater loss than g/m 2 of paver surface area or no greater loss than g/m 2 of paver surface area after freeze-thaw cycles. Freeze-thaw testing requirements shall be waived for applications not exposed to freezing conditions. 2.2 PRODUCT SUBSTITUTIONS A. Substitutions: No substitutions permitted. 2.3 BEDDING AND JOINT SAND A. Provide bedding and joint sand as follows: 1. Washed, clean, non-plastic, free from deleterious or foreign matter, symmetrically shaped, natural or manufactured from crushed rock. 2. Do not use limestone screenings, stone dust, or sand for the bedding sand material that does not conform to conform to the grading requirements of ASTM C Do not use mason sand or sand conforming to ASTM C 144 for the bedding sand. Note: If the pavement will be exposed to heavy traffic with trucks, i.e., a major thoroughfare with greater than 1.5 million 18-Kip (8 kn) equivalent single axle loads, contact ICPI for test method and criteria for assessing the durability of bedding sand. Pavestone Paver Specification Pg 3 of 7 2/9

5 4. Where concrete pavers are subject to vehicular traffic, utilize sands that are as hard as practically available. 5. Sieve according to ASTM C Bedding Sand Material Requirements: Conform to the grading requirements of ASTM C 33 with modifications as shown in Table 1. Table 1 Grading Requirements for Bedding Sand ASTM C 33 Sieve Size Percent Passing 3/8 in.(9.5 mm) No. 4 (4.75 mm) 95 to No. 8 (2.36 mm) 85 to No. 16 (1.18 mm) to 85 No. 3 (.6 mm) 25 to 6 No. (.3 mm) 1 to 3 No. (.1 mm) 2 to 1 No. (.75 mm) to 1 Note: Coarser sand than that specified in Table 2 below may be used for joint sand including C 33 material as shown in Table 1. Use material where the largest sieve size easily enters the smallest joints. For example, if the smallest paver joints are 2 mm wide, use sand 2 mm and smaller in particle size. If C 33 sand is used for joint sand, extra effort may be required in sweeping material and compacting the pavers in order to completely fill the joints. 7. Joint Sand Material Requirements: Conform to the grading requirements of ASTM C 144 as shown with modifications in Table 2 below: Table 2 Grading Requirements for Joint Sand ASTM C 144 ASTM C 144 Natural Sand Manufactured Sand Sieve Size Percent Passing Percent Passing No. 4 (4.75 mm) No. 8 (2.36 mm) 95 to 95 to No. 16 (1.18 mm) 7 to 7 to No. 3 (.6 mm) 4 to 75 4 to No. (.3 mm) 1 to 35 2 to 4 No. (.1 mm) 2 to 15 1 to 25 No. (.75 mm) to 1 to 1 Note: Specify specific components of a system, manufactured unit or type of equipment. See ICPI Tech Spec 3, Edge Restraints for Interlocking Concrete Pavements for guidance on selection and design of edge restraints. 2.4 EDGE RESTRAINTS A. Provide edge restraints installed around the perimeter of all interlocking concrete paving unit areas as follows: 1. Manufacturer: [Specify manufacturer.]. 2. Material: [Plastic] [Concrete] [Aluminum] [Steel] [Pre-cast concrete] [Cut stone] [Concrete.]. 3. Material Standard: [Specify material standard.]. 2.5 ACCESSORIES A. Provide accessory materials as follows: 1. Geotextile Fabric: a. Material Type and Description: [Specify material type and description.]. b. Material Standard: [Specify material standard.]. c. Manufacturer: [Acceptable to interlocking concrete paver manufacturer] [Specify manufacturer.]. Pavestone Paver Specification Pg 4 of 7 2/9

6 Note: Delete article below if cleaners, sealers, and/or joint sand stabilizers are not specified. 2. [Cleaners] [Sealers] [Joint sand stabilizers] a. Material Type and Description: [Specify material type and description.]. b. Material Standard: [Specify material standard.]. c. Manufacturer: [Specify manufacturer.]. PART 3 EXECUTION 3.1 ACCEPTABLE INSTALLERS A. [Specify acceptable paving subcontractors.]. 3.2 EXAMINATION Note: Compaction of the soil subgrade is recommended to at least 98% standard Proctor density per ASTM D 698 for pedestrian areas and residential driveways. Compaction to at least 98% modified Proctor density per ASTM D 1557 is recommended for areas subject to heavy vehicular traffic. Stabilization of the subgrade and/or base material may be necessary with weak or saturated subgrade soils. Note: Local aggregate base materials typical to those used for highway flexible pavements are recommended, or those conforming to ASTM D 294. Compaction of aggregate is recommended to not less than 98% Proctor density in accordance with ASTM D 698 is recommended for pedestrian areas and residential driveways. 98% modified Proctor density according to ASTM D 1557 is recommended for vehicular areas. Mechanical tampers are recommended for compaction of soil subgrade and aggregate base in areas not accessible to large compaction equipment. Such areas can include that around lamp standards, utility structures, building edges, curbs, tree wells and other protrusions. Note: Prior to screeding the bedding sand, the recommended base surface tolerance should be ±3/8 in. (±1 mm) over a 1 ft. (3 m) straight edge. See ICPI Tech Spec 2, Construction of Interlocking Concrete Pavements for further guidance on construction practices. Note: The elevations and surface tolerance of the base determine the final surface elevations of concrete pavers. The paver installation contractor cannot correct deficiencies in the base surface with additional bedding sand or by other means. Therefore, the surface elevations of the base should be checked and accepted by the General Contractor or designated party, with written certification to the paving subcontractor, prior to placing bedding sand and concrete pavers. A. Acceptance of Site Verification of Conditions: 1. General Contractor shall inspect, accept and certify in writing to the paver installation subcontractor that site conditions meet specifications for the following items prior to installation of interlocking concrete pavers. a. Verify that subgrade preparation, compacted density and elevations conform to specified requirements. b. Verify that geotextiles, if applicable, have been placed according to drawings and specifications. c. Verify that [Aggregate] [Cement-treated] [Asphalt-treated] [Concrete] [Asphalt] base materials, thickness, [compacted density], surface tolerances and elevations conform to specified requirements. d. Provide written density test results for soil subgrade, [aggregate] [cement-treated][asphalt-treated][asphalt] base materials to the Owner, General Contractor and paver installation subcontractor. e. Verify location, type, and elevations of edge restraints, [concrete collars around] utility structures, and drainage inlets. 2. Do not proceed with installation of bedding sand and interlocking concrete pavers until [subgrade soil and] base conditions are corrected by the General Contractor or designated subcontractor. Pavestone Paver Specification Pg 5 of 7 2/9

7 3.3 PREPARATION A. Verify base is dry, certified by General Contractor as meeting material, installation and grade specifications. B. Verify that base [and geotextile] is ready to support sand, [edge restraints,] and, pavers and imposed loads. C. Edge Restraint Preparation: 1. Install edge restraints per the drawings [and manufacturer s recommendations] [at the indicated elevations.]. Note: Retain the following two subparagraphs if specifying edge restraints that are staked into the base with spikes. 2. Mount directly to finished base. Do not install on bedding sand. 3. The minimum distance from the outside edge of the base to the spikes shall be equal to the thickness of the base. 3.4 INSTALLATION A. Spread bedding sand evenly over the base course and screed to a nominal 1 in. (25 mm) thickness, not exceeding 1 1/2 in. (4 mm) thickness. Spread bedding sand evenly over the base course and screed rails, using the rails and/or edge restraints to produce a nominal 1 in. (25 mm) thickness, allowing for specified variation in the base surface. 1. Do not disturb screeded sand. 2. Screeded area shall not substantially exceed that which is covered by pavers in one day. 3. Do not use bedding sand to fill depressions in the base surface. Note: When initially placed on the bedding sand, manually installed pavers often touch each other, or their spacer bars if present. Joint widths and lines (bond lines) are straightened and aligned to specifications with rubber hammers and pry bars as paving proceeds. B. Lay pavers in pattern(s) shown on drawings. Place units hand tight without using hammers. Make horizontal adjustments to placement of laid pavers with rubber hammers and pry bars as required. Note: Contact manufacturer of interlocking concrete paver units for recommended joint widths. C. Provide joints between pavers between [1/16 in. and 3/16 in. (2 and 5 mm)] wide. No more than 5% of the joints shall exceed [1/4 in. (6 mm)] wide to achieve straight bond lines. D. Joint (bond) lines shall not deviate more than ±1/2 in. (±15 mm) over ft. (15 m) from string lines. E. Fill gaps at the edges of the paved area with cut pavers or edge units. F. Cut pavers to be placed along the edge with a [double blade paver splitter or] masonry saw. Note. Specify requirements for edge treatment in paragraph below. G. [Adjust bond pattern at pavement edges such that cutting of edge pavers is minimized. All cut pavers exposed to vehicular tires shall be no smaller than one-third of a whole paver.] [Cut pavers at edges as indicated on the drawings.] H. Keep skid steer and forklift equipment off newly laid pavers that have not received initial compaction and joint sand. I. Use a low-amplitude plate compactor capable of at least minimum of 4, lbf (18 kn) at a frequency of 75 to Hz to vibrate the pavers into the sand. Remove any cracked or damaged pavers and replace with new units. J. Simultaneously spread, sweep and compact dry joint sand into joints continuously until full. This will require at least 4 to 6 passes with a plate compactor. Do not compact within 6 ft (2 m) of unrestrained edges of paving units. K. All work within 6 ft. (2 m) of the laying face must shall be left fully compacted with sand-filled joints at the end of each day or compacted upon acceptance of the work. Cover the laying face or any incomplete areas with plastic sheets overnight if not closed with cut and compacted pavers with joint sand to prevent exposed bedding sand from becoming saturated from rainfall. L. Remove excess sand from surface when installation is complete. Pavestone Paver Specification Pg 6 of 7 2/9

8 Note: Excess joint sand can remain on surface of pavers to aid in protecting their surface especially when additional construction occurs after their installation. If this is the case, delete the article above and use the article below. Designate person responsible for directing timing of removal of excess joint sand. M. Allow excess joint sand to remain on surface to protect pavers from damage from other trades. Remove excess sand when directed by [Architect]. Do not allow vehicular traffic on pavers with sand on top of the surface. N. Surface shall be broom clean after removal of excess joint sand. 3.5 FIELD QUALITY CONTROL Note: Surface tolerances on flat slopes should be measured with a rigid straightedge. Tolerances on complex contoured slopes should be measured with a flexible straightedge capable of conforming to the complex curves on the pavement surface. A. The final surface tolerance from grade elevations shall not deviate more than ±3/8 in. (±1 mm) under a 1 ft (3 m) straightedge. B. Check final surface elevations for conformance to drawings. Note: For installations on a compacted aggregate base and soil subgrade, the top surface of the pavers may be 1/8 to 1/4 in. (3 to 6 mm) above the final elevations after compaction. This helps compensate for possible minor settling normal to pavements. C. The surface elevation of pavers shall be 1/8 in. to 1/4 in. (3 to 6 mm) above adjacent drainage inlets, concrete collars or channels. D. Lippage: No greater than 1/8 in. (3 mm) difference in height between adjacent pavers. Note: Cleaning and sealing may be required for some applications. See ICPI Tech Spec 5, Cleaning and Sealing Interlocking Concrete Pavements for guidance on when to clean and seal the paver surface, and when to stabilize joint sand. Delete article below if cleaners, sealers, and or joint sand stabilizers are not applied. 3.6 [CLEANING] [SEALING] [JOINT SAND STABILIZATION] A. [Clean] [Seal] [Apply joint sand stabilization materials between] concrete pavers in accordance with the manufacturer s written recommendations. 3.7 PROTECTION A. After work in this section is complete, the General Contractor shall be responsible for protecting work from damage due to subsequent construction activity on the site. END OF SECTION Pavestone Paver Specification Pg 7 of 7 2/9

9 Concrete Pave Stones Plaza Stone Series 7 by Pavestone Company. All Rights Reserved., Improving Your Landscape, Provencial Series and Heritage Series are trademarks of the Pavestone Company. Member of ASLA and NCMA Atlanta, GA: (77) Austin/San Antonio, TX: (512) Boston, MA: (8) Cartersville, GA (77) Charlotte, NC: (74) Cincinnati, OH: (513) Colorado Springs, CO: (719) Dallas/Ft. Worth, TX: (817) Denver, CO: (33) Hagerstown, MD: (24) ICPI Charter Member Houston, TX: (281) Kansas City, MO: (816) Las Vegas, NV: (72) New Orleans, LA: (985) Phoenix, AZ: (62) Sacramento/ Winters, CA: (53) St. Louis/ Cape Girardeau, MO: (573) Retaining Wall Systems SKU# CM 53v8 12/6 IMPROVING YOUR LANDSCAPE

10 Plaza Stone Series Plaza Stone is a timeless paving stone with an impressionistic embossed surface profile. It creates a gentle and warm effect by combining the soft curved edges of the rectangular and square stones. Plaza Stone is available in many colors and in standard or Heritage Series (tumbled) finish to accommodate the most discriminating tastes and desires. Plaza Stone uses large-scale patterns to create interest and drama to commercial landscaping, while the stone s texture and pattern harmonize with surrounding buildings and site furnishings. COMPOSITION AND MANUFACTURE Plaza Stone is made from a no slump concrete mix. Made under extreme pressure and high frequency vibrations, Plaza Stone has a compressive strength greater than 8psi, a water absorption maximum of 5% and will meet or exceed ASTM C-936 and freeze-thaw testing per Section 8 of ASTM C-67. Heritage Series may not comply with ASTM C-67 freeze-thaw durability. INSTALLATION 1. Excavate unsuitable, unstable or unconsolidated subgrade material and compact the area which has been cleared. Backfill and level with dense graded aggregate suitable for base material (typically 4 in. to 8 in. (11mm to 22mm) of compacted base for light vehicular and pedestrian traffic) or as otherwise directed by Site Engineer/ Architect/ Landscape Architect. 2. Place bedding course of washed sand conforming to the grading requirements of ASTM C-33 to a uniform depth of / 2 in. (25-38mm) screeded to the grade and profile required. 3. Install Plaza Stone with joints approximately 1 / 8 in. (3mm). 4. Where required, cut pave stones with an approved cutting device to fit accurately, neatly and without damaged edges. 5. Tamp pave stones with a plate compactor, uniformly level, true to grade and free of movement. 6. Spread sand to 1 / 8 in. (3mm) thickness over entire paving area. Heritage Series may require joint sand stabilization. 7. Make one more pass with plate compactor to fill joints with sand. Complete installation & specification details are available by contacting your Pavestone Sales Representative. Note: Colors are shown as accurately as possible in brochures & samples, but due to the nature of the product, regional color differences and variables in print reproduction, colors may not match exactly. For best results in maintaining color consistency, pavers must be installed from several cubes at a time. Efflorescence, a whitish, powder-like deposit, may appear on concrete pavers. This is a natural occurrence in any concrete product and will usually wear off over time. INSTALLATION PATTERNS Plaza I Runner Bond Plaza II Runner Bond Plaza I Muster K Plaza I & II Random Plaza IV Circle Plaza III Fan Plaza I, II & Giant Random Typical Cross Section of Concrete Pave Stone Installation Sand-Filled Joints Pave Stones Sand APPLICATIONS General Road Construction Parking Lots Driveways Patios Bridge Underpasses Entrance Areas Flooring in Stables Sidewalks Terraces Garden Pathways Pool Decks Pedestrian Malls Roof Gardens PRODUCT INFORMATION Plaza Stone is available in eight (8) sizes. Height/Thickness 6mm = 2 3 / 8", 8mm = 3 1 / 8"* Available in standard and Heritage tumbled finishes. Plaza Stone Large Rectangles Only Nominal Dimensions 5 7 / 16" W x 8 3 / 16" L 138mm x 28mm Height/Thickness 2 3 / 8" = 6mm 3 1 / 8" = 8mm Wt./Stone lbs lbs. Stones/Sq.Ft Stones/Pallet 3 24 Approx. Wt./Pallet 2,66 lbs. 2,736 lbs. Sq. Ft./Pallet Product Number Plaza II Stone Med. Rec. & Sm. Rec. Bundled Together Nominal Dimensions Med. Rec: 4 1 / 16" W x 5 7 / 16" L 13mm x 138mm Sm. Rec: 2 11 / 16" W x 5 7 / 16" L 68mm x 138mm Height/Thickness 2 3 / 8" = 6mm Stones/Pallet 8 Sm. Rec. 56 Med. Rec. Approx. Wt./Pallet 2,8 lbs. Sq. Ft./Pallet Product Number 626 Plaza Stone Parkway Lg. Rectangles Only Nominal Dimensions 5 7 / 16" W x 8 3 / 16" L 138mm x 28mm Height/Thickness 2 3 / 8" = 6mm Wt./Stone lbs. Stones/Sq.Ft. 3.2 Stones/Pallet 3 Approx. Wt./Pallet 2,66 lbs. Sq. Ft./Pallet 95 Product Number 66F T Plaza Stone Squares Only Nominal Dimensions 5 7 / 16" W x 5 7 / 16" L 138mm x 138mm Height/Thickness 2 3 / 8" = 6mm 3 1 / 8" = 8mm Wt./Stone 6 lbs. 7.4 lbs. Stones/Sq.Ft Stones/Pallet Approx. Wt./Pallet 2,8 lbs. 2,88 lbs. Sq. Ft./Pallet 8 Product Number Plaza III Stone Fan Pack (Bundled Together) Center Rec, Lg. Center Wedge, Left Wedge, Right Wedge Nominal Dimensions (A) Center Rec: 2 11 / 16" W x 5 1 / 2" L (B) Lg. Center Wedge: 6 1 / 4" W x 5 1 / 2" L 68mm x 138mm 157mm x 138mm (C) Left Wedge: 3 1 / 16" W x 5 1 / 2" L (D) Right Wedge: 3 1 / 16" W x 5 1 / 2" L 77.5mm x 138mm 77.5mm x 138mm Height/Thickness 2 3 / 8" = 6mm Stones/Pallet 3 Center Rec. (A) 3 Lg. Center Wedge (B) 12 Left Wedge (C) 12 Right Wedge (D) Approx. Wt./Pallet 2,856 lbs. Sq. Ft./Pallet 12 Product Number 636 Plaza Stone Parkway Squares Only Nominal Dimensions 5 7 / 16" W x 5 7 / 16" L 138mm x 138mm Height/Thickness 2 3 / 8" = 6mm Wt./Stone 6 lbs. Stones/Sq.Ft. 4.8 Stones/Pallet 48 Approx. Wt./Pallet 2,8 lbs. Sq. Ft./Pallet Product Number 646F T Plaza I Stone Large Rec. & Squares Bundled Together Nominal Dimensions Square: 5 7 / 16" W x 5 7 / 16" L 138mm x 138mm Large Rec: 5 7 / 16" W x 8 3 / 16" L 138mm x 28mm Height/Thickness 2 3 / 8" = 6mm Stones/Pallet 24 Sq. 18 Rec. Approx. Wt./Pallet 3,8 lbs. Sq. Ft./Pallet 11 Product Number 616 Giant Plaza Stone Nominal Dimensions 8 3 / 16" W x 1 15 / 16" L 28mm x 278mm Height/Thickness 2 3 / 8" = 6mm Wt./Stone lbs. Stones/Sq. Ft. 1.6 Stones/Pallet 16 Approx. Wt./Pallet 2,828 lbs. Sq. Ft./Pallet 11 Product Number 649 Plaza IV Stone Circle Pack (Bundled Together) Center, Lg Cir. Wedge, Sm Cir. Wedge, Small Cir. Rec., Large Cir. Rec. Nominal Dimensions (A) Center: 2 11 / 16" W x 5 1 / 2" L (D) Sm. Cir. Rec: 2 11 / 16" W x 5 1 / 2" L 68mm x 138mm 68mm x 138mm (B) Lg. Cir: Wedge 6 1 / 16" W x 5 1 / 2" L (E) Lg. Cir. Rec: 4 1 / 8" W x 5 1 / 2" L 157mm x 138mm 13mm x 138mm (C) Sm. Cir. Wedge: 4 9 / 16" W x 5 1 / 2" L 114.7mm x 138mm Height/Thickness 2 3 / 8" = 6mm Stones/Pallet 1 Center Stone (A) 2 Lg. Cir. Wedge(B) 28 Sm. Cir. Wedge (C) 1 Sm. Cir. Rec. (D) 22 Lg. Cir. Rec. (E) Approx. Wt./Pallet 2,352 lbs. Sq. Ft./Pallet 84 *Fractional dimensions are nominal. Product Number 637 Plaza Stone Heritage Series is sold on pallets or in bags. There is approximately the same square feet/pallet in each bagged product after tumbling. Packaging may vary from plant to plant. Contact your Pavestone Company manufacturer for packaging details.

11 Permeable Interlocking Concrete Pavement (PICP) For Municipal Officials FACT SHEET PICP Stormwater Benefits Reduces pollutants from rainwater runoff Complements buildings and visually unifies streetscape, many colors available LEED points eligible for Sustainable Sites, Water Efficiency, Materials & Resources and/or Innovative Design; Earns Green Globe points Meets U.S. Environmental Protection Agency stormwater performance criteria as a structural best management practice (BMP) while providing parking, road and pedestrian surfaces Helps meet local, state and provincial stormwater drainage design criteria and provides compliance with the U.S. National Pollutant Discharge Elimination System (NPDES) regulations Reduces runoff from common rainstorms by as much as %; eliminates surface puddles and local flooding Promotes street tree survival Snow melts faster on permeable pavement and drains, reducing ice hazards Snow plow with typical snow removal equipment; reduce winter ice hazards, deicing salt use and snow removal costs. year life-cycle for surface Compatible with underground stormwater storage systems, many slower-draining clay soils and cold climates Governments may offer tax incentives, utility fee reductions, expedited permitting or a demonstration project to encourage use. 3 1/8 in. (8 mm) thick pavers with permeable joints Open-graded bedding course Open-graded base course Open-graded subbase on non-compacted soil subgrade Permeable interlocking concrete pavement (PICP) with open-graded base and subbase for infiltration and storage. PICP supports sustainable development and livable green communities PICP s can eliminate street storm drains and sewer pipes as in this redevelopment project in Seattle,WA. Application Opportunities This PICP fire station driveway in Snoqualmie, WA eliminates runoff during most rainstorms. Public Projects: Office plazas, parks, sidewalk replacement, street tree planting areas, parking lots and outdoor seating areas Private Projects: Parking lots, parks, driveways, parking bays on roadways, subdivision roads and sidewalks Public-Private Partnerships & Redevelopment Sites: Parking areas, plazas and public spaces and sidewalks stormwater management environmentally sustainable reduces urban heat island community development tool

12 LID Integrated with PICP PICP Meets LID Goals Conserves on-site space: roads, parking, stormwater infiltration and retention all combined into the same space creating more green space or building opportunities Preserves wooded areas that would otherwise be cleared for stormwater detention or retention ponds Increases site infiltration that helps maintain pre-development runoff volumes, peak flows and time of concentration Promotes tree survival and growth Contributes to urban heat island reduction through evaporation and reflective, light colored pavers Highly visible, cost-effective exemplary demonstration of a cornerstone LID technique for public and private development Permeable Interlocking Concrete Pavement: A Low Impact Development Tool PICP Supports LID Principles 1. Conserve vital ecological and natural resources: trees, streams, wetlands and drainage courses 2. Minimize hydrologic impacts by reducing imperviousness, conserving natural drainage courses, reducing clearing, grading and pipes 3. Maintain pre-development time of concentration for runoff by routing flows to maintain travel times and discharge control 4. Provide runoff storage and infiltration uniformly throughout the landscape with small, on-site decentralized infiltration, detention and retention practices such as permeable pavement, bioretention, rain gardens, open swales and roof gardens 5. Educate the public and property owners on runoff and pollution prevention measures and benefits 2 Municipal civic goals may be met using PICP as part of an integrated approach to development and redevelopment.

13 Construction and Project Examples Prepared subgrade for 2, sf ( m²) Portland, OR street retrofit with PICP Portland, OR street project with PICP parking lanes Aggregate base is spread and compacted; pavers are delivered ready to install. After placement of bedding course, joints and/or openings are filled with small aggregate and the pavers are compacted. Joints may be filled mechanically as shown. Mechanical installation speeds construction. construction uses locally available materials. Chicago Green Alley Program before and after PICP installation Green Alleys are being implemented to manage stormwater, reduce combined sewer overflows, reduce urban heat in urban areas, and conserve energy. Typical PICP cross section Photos: Courtesy of the City of Chicago Design Software Available New software from ICPI for permeable pavement called Permeable Design Pro incorporates research from a range of university research studies. Contact ICPI for further information. 3

14 Performance Volume Reduction PICP significantly reduces runoff from most storms. Runoff volume reductions relieve flooding in storm sewers operating at capacity and relieve sewage treatment plants receiving combined storm and sanitary waste flows. Reduced runoff can reduce sewer overflows and stream bank erosion. Peak Flow Reduction Promotes stream and lake health with decreased erosion Reduces water pollution by reducing combined sewer overflow frequency Reduces the need for continuous expansion of drainage infrastructure Additional Benefits Cooler than conventional pavements ADA compliant May be used on sloped site with proper design Simplified surface and subsurface repairs by reinstating the same paving units; no unsightly patches or weakened pavement from utility cuts Can be used for traffic calming Water Quality Improvement 8% or greater TSS removal Preserve and increase drinking and recreational water supplies; preserve aquatic and wildlife habitats. Gain recognition for innovative design through sustainable BMPs FAQs Can PICP be used on clay soils? Yes. Even in clay soils, PICP reduces runoff and helps to capture first flush runoff and reduce pollution. Can PICP be used to replace every kind of pavement? PICP is best suited for use in areas of low speed traffic such as parking lots, residential streets, driveways, patios, plazas, sidewalks and parking lanes on busier travelways. Nevertheless, PICP has been successfully used even under heavy commercial loads. Will PICP enhance property values? The data from installed PICP projects indicates that PICP meets multiple criteria for project success including enhancing property values. Is Maintaining PICP difficult? No. PICP can be maintained through street sweeping and vacuuming based on periodic inspection. References Ferguson, B. K. Porous Pavements. Boca Raton, FL:CRC Press, 5. Smith, David R. Permeable Interlocking Concrete Pavements: Selection Design Construction Maintenance, Herndon, VA:ICPI 3rd ed., 6. www. icpi.org. For more information pertaining to permeable interlocking concrete pavement, please visit the Interlocking Concrete Pavement Institute (icpi.org) or the Low Impact Development Center (lowimpactdevelopment.org). Other Fact Sheets available for Developers, Design Professionals and Schools/Universities The Low Impact Development Center, Inc. Disclaimer: The content of this brochure is intended for use only as a guideline. It is not intended for use or reliance upon as an industry standard, certification or specification. ICPI & LIDC make no promises, representations or warranties of any kind, expressed or implied, as to the content of this brochure. Professional assistance should be sought with respect to the design, specifications and construction of each permeable interlocking concrete pavement project. Copyright 8 Interlocking Concrete Pavement Institute. All Rights Reserved Park Center Road Suite 27 Herndon, VA 2171 Tel: Fax: icpi@icpi.org Web: CANADA P.O. Box 11 Uxbridge, ON L9P 1N4 Canada 4

15 TECH SPEC N u m b er 4 Structural Design of Interlocking Concrete Pavement for Roads and Parking Lots History The concept of interlocking concrete pavement dates back to the roads of the Roman Empire. See Figure 1. They were c o n st ruc te d w i t h tightly-fitted stone paving units set on a compacted aggregate base. The modern version, concrete pavers, is manufactured with close tolerances to help ensure inter- Figure 1. The Roman Appian Way: lock. Concrete pavers early interlocking pavement were developed in the Netherlands in the late 194s as a replacement for clay brick streets. A strong, millennia-old tradition of segmental paving in Europe enabled interlocking concrete pavement to spread quickly. It is now established as a conventional means of paving there with some four billion ft2 (4 million m2) installed annually. Concrete pavers came to North America in the 197s. They have been used successfully in numerous residential, commercial, municipal, port and airport applications. This Tech Spec covers the structural design of interlocking concrete pavement over an aggregate base as well as asphalt and cement stabilized bases, asphalt concrete and Portland cement concrete bases. Advantages The paving system offers the advantages of concrete materials and flexible asphalt pavement. As high-strength concrete, the units have high resistance to freeze-thaw cycles and deicing salts, high abrasion and skid resistance, no damage from petroleum products or indentations from high temperatures. Once installed, there is no waiting time for curing. The pavement is immediately ready for traffic. Cracking and degradation of the surface is minimized because of the numerous joints (and sand in them) which act as a means for load transfer without damaging the pavement surface. Like flexible asphalt pavement, an aggregate base accommodates minor settlement without surface cracking. An aggregate base facilitates fast construction, as well as access to underground utilities. Mechanical installation of concrete pavers can further shorten construction time and costs. Pavement reinstatement is enhanced by reusable paving units, thereby minimizing costs and reducing waste. The Principle of Interlock Interlock is the inability of a paver to move independently from its neighbors. It is critical to the structural performance of interlocking concrete pavement. When considering design and construction, three types of interlock must be achieved: vertical, rotational, and horizontal interlock. These are illustrated in Figure 2. Vertical interlock is achieved by the shear transfer of loads to surrounding units through sand in the joints. Rotational interlock is maintained by the pavers being of sufficient thickness, meeting recommended plan and aspect ratios, placed closely together, and restrained by a curb from lateral forces of vehicle tires. Rotational interlock can be further enhanced if there is a slight crown to the pavement cross section. Besides facilitating drainage, the crown enables the pavement surface to stiffen and further lock up as the pavement undergoes vehicle loading due to traffic. Horizontal interlock is primarily achieved through the use of laying patterns that disperse forces from braking, turning and accelerating vehicles. Herringbone patterns are the most effective laying patterns for maintaining interlock (see Figure 3). Testing has shown that these patterns of ICPI Tech Spec No. 4 Interlocking Concrete Pavement Institute All rights reserved Revised May 211

16 Load Load Horizontal Displacement Load Load Load Load Displaced Bedding Sand Displaced Bedding Sand Horizontal Displacement No Vertical Interlock No Horizontal Interlock Horizontal Displacement No Rotational Interlock Load Load Load Horizontal Interlock Rotational Interlock Vertical Interlock Figure 2. Types of interlock: horizontal, vertical, rotational fer greater structural capacity and resistance to lateral movement than other laying patterns (Shackel 1979 and 198). Therefore, herringbone patterns are recommended in areas subject to vehicular traffic. See Figure 3. Stable edge restraints such as curbs are essential. They provide better horizontal interlock among the units while they are subject to repeated lateral loads from vehicle tires. ICPI Tech Spec 3, Edge Restraints for Interlocking Concrete Pavements offers guidance on the selection and detailing of edge restraints for a range of applications. Typical Pavement Design and Construction Flexible pavement design uses untreated aggregate, cement- or asphalt-treated aggregates or asphalt under the concrete pavers and bedding layer. Flexible pavements distribute the loads to the subgrade by spreading them through consecutively weaker layers to the compacted soil subgrade. Such pavements are often preferred in colder climates because they can offer greater protection against frost heaving. Figure 4 illustrates typical schematic cross sections for interlocking concrete pavement designed as a flexible system. Both the base and subbase are compacted aggregate. Some road agencies may use open-graded drainage bases as well. Many pavements for city and residential uses do not require an aggregate subbase except for very heavy use or over a weak soil subgrade. In these situations it may be more economical to use asphalt or cement-stabilized base layers. They are often placed over a subbase layer of unbound compacted aggregate. Construction is covered in ICPI Tech Spec 2, Construction of Interlocking Concrete Pavement. The steps for preparing the soil subgrade and base materials are similar to those required for flexible asphalt pavements. After the base surface is built to specified elevations and surface tolerances, bedding sand is screeded in an even layer, typically 1 in. (25 mm) thick. The units are placed, manually or mechanically, on the even bedding sand constrained by stationary edge restraints. 45 Herringbone 9 Herringbone Figure 3. Laying patterns for vehicular traffic Page 2

17 Concrete Pavers Edge Restraint/ Curb Joint Sand Bedding Sand Compacted Unbound Aggregate Compacted Unbound Aggregate Sub- Compacted Subgrade Soil (A) Unbound / Concrete Pavers Edge Restraint/ Curb Joint Sand Bedding Sand Compacted Cement or Asphalt Treated Compacted Unbound Aggregate Sub- Compacted Subgrade Soil (B) Cement or Asphalt Treated Figure 4. Typical schematic cross sections The pavers are vibrated with a high frequency plate compactor. This action forces sand into the bottom of the joints of the pavers and begins compaction of the bedding sand. Sand is then spread and swept into the joints, and the process repeated until the joints are filled. Complete compaction of the sand and slight settlement of the pavers tightens them. During compaction, the pavement is transformed from a loose collection of pavers to an interlocking system capable of spreading vertical loads horizontally. This occurs through shear forces in the joints. Structural Design Procedure The load distribution and failure modes of flexible asphalt and interlocking concrete pavement are very similar: permanent deformation from repetitive loads. Since failure modes are similar, flexible pavement design procedures are used. The structural design procedures are for roads and parking lots. design for crosswalks should consider using stablized aggregate or cast-in-place concrete with sand-set paving units, or bitumen-set paving units over concrete. Stiffer bases will compensate for stress concentration on the subgrade and base where the pavers meet adjoining pavement materials. Design for heavy duty pavements such as port and airport pavements is covered in ICPI manuals entitled, Port and Industrial Pavement Design for Concrete Pavers and Airfield Pavement Design with Concrete Pavers. Design Methodology Structural design of interlocking concrete pavements follows the American Society of Civil Engineers Transportation & Development Institute standard (ASCE/T&DI 58-1), Structural Design of Interlocking Concrete Pavement for Municipal Streets and Roadways (ASCE 21). This standard applies to paved areas subject to applicable permitted axle loads and trafficked up to 1 million (18, lb or 8 kn) equivalent single axle loads (ESALs) with a vehicle speed of up to 45 mph (7 km/h). The standard provides preparatory information required for design, key design elements, design tables for pavement equivalent structural design, construction considerations, applicable standards, definitions and best practices. Readers are encouraged to purchase and review this guideline standard. The ASCE standard relies on the flexible pavement design method described in the 1993 Guide for Design of Pavement Structures published by the American Association of State Highway and Transportation Officials (AASHTO 1993). Future versions of the ASCE standard may include the mechanistic-empirical design methodology as described in the 4 Guide for Mechanistic Empirical Design of New and Rehabilitated Pavement Structures (AASHTO 4). The level of detailed information required to use this procedure is unavailable for most non-highway applications. The design process is characterized by the flowchart shown in Figure 5. The following provides information on the key input variables noted in the flowchart. Design Traffic When pavement is trafficked, it receives wear or damage usually evidenced as the depth of rutting in flexible asphalt pavements and the extent of cracking in rigid concrete pavements. For interlocking concrete pavements, damage is typically measured by the depth of rutting since it behaves as a flexible pavement similar to asphalt. Cracked paving units are rarely evidence of a pavement damaged by traffic loads and therefore are not typically used as a means to estimate damage or wear of an interlocking concrete pavement. As with all pavements, the amount of damage from traffic depends on the weight of the vehicles and the number of expected passes over a given period of time. The period of time, or design life, is 2 to 4 years. Design life is the period of time a pavement will last before damage requires major rehabilitation, often complete removal and replacement. The designer or transportation agency selects a design life in years which is influenced by the available budget to construct or rehabilitate a pavement. Predicting traffic over the life of the pavement is an estimate of various vehicle loads, axle and wheel configurations, and the number of loads (repetitions). The actual amount of traffic loads can often exceed the predicted loads. Therefore, engineering judgment is required in estimating expected sources of traffic and loads well into the future. When future traffic loads are difficult to predict, an engineer will often design a pavement for higher loads Page 3

18 Figure 5. Design Process Flow Chart *Indicates outside scope of the standard Page 4

19 to ensure that the risk of excessive pavement damage is low over the service life of the pavement. Compared to cars, trucks and busses do the most damage to pavements because their wheel loads are much higher than cars. One pass of a fully loaded truck will exert more damage to pavement than several thousand cars passing over it. Since there is a range of expected loads (usually expressed as axle loads) over a pavement during its life, AASHTO developed a means to normalize or equalize all axle loads of them into a single axle load exerted repeatedly over the life of the pavement. The 1993 AASHTO Guide characterizes traffic loads as the number of 8 kn or 18, lbs equivalent single axle loads or ESALs. The 18, lbs (8 kn) load emerged from AASHTO (then called AASHO) road tests conducted in the 19s and have remained as a convenient means to quantify a range of different vehicle axle loads. The AASHTO tests demonstrated that loads and resulting damage to pavement is not linear but exponential as loads increase. The tests showed that for every incremental increase in axle load, damage to the pavement increased by roughly the fourth power. This exponential load-damage relationship resulted in determining ESALs by taking the weight of each axle and dividing each by a standard ESAL of 18, lbs or 8 kn. Then the quotient is raised to the fourth power. For example, a five axle tractor-trailer truck has two rear axles on the trailer each exerting 18, lbs or 8 kn; two on the back of the truck at 15,8 lbs or 7 kn; and one in the front (steering) at 11, lbs or kn. AASHTO uses the following relationships called load equivalency factors or LEFs for each axle to estimate ESALs. These express the exponential relationship between damage and loads. LEF and ESALs for this truck are as follows: doubling the axle load increases the damage 16 times. The California Department of Transportation or Caltrans uses Traffic Index or TI rather than ESALs. Converting ESALs to TI is accomplished by using the formula below. Table 1 illustrates the relationships between ESALs and TIs. Table 2 provides AASHTO road classifications and typical lifetime ESALs and TIs. For the ASCE standard, ESAL levels are provided for 1 Table 1. Relationship of ESALs to Caltrans TIs Trailer: LEF = (8/8)4 = 1 (x 2 axles) = 2 ESALs Truck rear: LEF= (7/8)4 =.6 (x 2 axles) = 1.2 ESALs Truck front: LEF = (/8) =.15 ESALs ESAL TI 5x14 6 1x 6.8 3x 7.2 5x 8.3 7x 8.6 1x16 9 3x x x x x x When added together, all LEFs = 3.35 ESALs. So for every pass across a pavement, this truck exerts kn (18, lbs) ESALs. To put automobile axle loads into perspective, the axle loads of one passenger car placed into the formula yields about.2 ESALs. Therefore, pavement design primarily considers trucks and busses because they exert the highest loads and most damage. In contrast, thousands of cars are required to apply the same loading and damage as one passage of a truck. The more axles on trucks the better, since tandem axles spread loads over a wider area and render lower damage for each pass of the vehicle over a pavement. Another way to illustrate this is one single axle load of 36, lbs (16 kn) exerts the same damage as 16 passes of a single axle load of 18, lbs (8 kn) or (36/18)4 = 16. Therefore, typical levels of municipal traffic up to a maximum of 1 million ESALs. The designer needs to select the appropriate traffic level and design life. The typical initial design life for municipal pavements is on the order of 2 to 4 years. Subgrade Characterization The next step is for the designer to characterize the subgrade soil and drainage for the purpose of selecting a subgrade strength. Typically the resilient modulus or Mr (AASHTO T-274) is used to describe the strength of the subgrade soil. This can be determined directly from laboratory testing. Other means to characterize soil strength include California Bearing Ratio or CBR (ASTM D1883) and R-value (ASTM D2844) tests. The relationship of Mr, CBR and R-value of subgrade soils are illustrated in Figure 6 which also includes strength ranges Page 5

20 Table 2. AASHTO Lifetime ESALs (Caltrans TI) D2487). Soil categories in Table 3 are from the stanesal (TI) dard and are provided to Commercial/ Road Class Arterial Major Minor the user for guidance only. Multi-Family or Major Streets Collectors Collectors Actual laboratory charlocals acterization of subgrade 7,, 2,8, 1,3, 43, Urban properties for each project (11.4) (1.2) (9.3) (8.1) is recommended. Design3,6, 1,, 5, 28, ers are cautioned against Rural (1.5) (9.4) (8.4) (7.7) making generalizations. Once the general subfor soils classified using the Unified (ASTM D2487), and grade type has been selected, then the drainage quality of the subgrade and pavement structure is characterized (See AASHTO methods. The ASCE standard utilizes eight categories of subgrade Table 4). Depending on the type of subgrade, the strength quality ranging from good quality gravels and rock with of the pavement may be reduced if there is excess water excellent drainage to poor quality clay materials that are in the subgrade. The standard includes an adjustment to semi-impervious to water. Subgrade types are classified the resilient modulus of the subgrade based on the overall according to the Unified Soils Classification method (ASTM quality of the pavement drainage, as shown in Table 5. Subgrade Soil Category Mr (ksi) R-Value 4 1 CBR (%) Medium Excellent AASHTO Soil Classification (M-145) A A-2-5 A-3 A-4 A-5 A-6 A-7-6 A-7-5 CH MH CL ML Unified Soil Classification (ASTM 2487) SP SW -SC SW SW - SM SP - SC SP - SM SC SM GW GP GW - GC GW - GM GP - GC GP - GM GC GM A-1-b A A-1-a A-2-4 Figure 6. Typical Resilient Modulus Correlations to Empirical Soil Properties and Classification Categories. From Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures, Appendix CC-1: Correlation of CBR Values with Soil Index Properties, National Cooperative Highway Research Program, Transportation Research Board, National Research Council, authored by ARA, Inc., Champaign, Illinois, March 1. Chart is modified from the National Asphalt Pavement Association Information Series 117, Guidelines for Use of HMA Overlays to Rehabilitate PCC Pavements, Page 6 Figure 1. Typical Resilient Modulus Correlations to Empirical Soil Properties and Classification Categories. (Modified from NAPA Information Series 117, "Guidelines for Use of HMA Overlays to Rehabilitate PCC Pavements", 1994)

21 Table 3. General Soil Categories and Properties (ASCE 21) Category No. Unified Soil Classification Drainage Characteristics Brief Description Susceptibility to Frost Action 1 Boulders/cobbles Rock, rock fill, shattered rock, boulders/ Excellent cobbles None 2 GW, SW Well graded gravels and sands suitable as granular borrow Excellent Negligible 3 GP, SP ly graded gravels and sands Excellent to fair Negligible to slight 4 GM, SM Silty gravels and sands to semi-impervious Slight to moderate 5 GC, SC Clayey gravels and sands Practically impervious Negligible to slight 6 ML, MI Silts and sandy silts Typically poor Severe 7 CL, MH Low plasticity clays and compressible silts Practically impervious Slight to severe 8 CI, CH Medium to high plasticity clays Semi-impervious to impervious Negligible to severe Table 4. Pavement Drainage According to Soil Category (ASCE 21) Quality of Drainage Time to Drain Soil Category No. from Table 3 1 day 1,2,3 7 days 3,4 1 month 4,5,6,7,8 abrasion) and a maximum loss of 4% when tested in accordance with ASTM C 131 or CSA A A (Los Angeles abrasion). The required plasticity index is a maximum of 6 and the maximum liquid limit of 25 when tested in accordance with ASTM D4318 and AASHTO T-89 and T-9. For constructability purposes, the minimum design unbound base thickness is 4 in. ( mm) for traffic less than, ESALs and 6 in. (1 mm) for, or higher ESALs. Figure 7 illustrates a typical cross section with an unstabilized, dense-graded base. For bound or treated bases, asphalt-treated base (ATB) and cement-treated base (CTB) materials and installation are required to conform to provincial, state or local specifications for a dense-graded, compacted, asphalt concrete. ATB material is required to have a minimum Marshall stability Selection of Material The next step in the design process is selecting the type of base material for the pavement. The standard supports the use of bound and unbound bases. For unbound dense-graded bases, the aggregates are required to be crushed, angular materials. Crushed aggregate bases used in highway construction are generally suitable for interlocking concrete pavement, and unbound base matable 5. Resilient Modulus terials should meet the local state, Conditions (ASCE 21) provincial or municipal standards governing base materials. Category Where local specifications are Mr R unavailable, the base material is (MPa) required to meet the gradation requirements according to ASTM D 294. Table 6 includes these re quirements. The minimum required strength of the unbound base is a 4 11 CBR of 8% or equivalent bearing strength as described by the test methods in Section 3.6 of the stan6 3 6 dard. Unbound base materials are required to have a maximum loss of 6% when tested in accordance with CSA A A (Micro-Deval (Mr), R-Values and CBRs for Subgrade Drainage Drainage CBR Mr (MPa) R CBR Mr (MPa) R CBR Page 7

22 Table 6. ASTM D 294 Gradation for Unbound Aggregate s and s Design Range* (Mass Percentages Passing) Sieve Size (square openings) Job Mix Tolerances (Mass Percentages Passing) s s s s 2 in. ( mm) /2 in. (37.5 mm) 95 to 9 to ±5 +5 3/4 in. (19 mm) 7 to 92 ±8 3/8 in. (9.5 mm) to 7 ±8 No. 4 (4.75 mm) 35 to 55 No. 3 (.6 mm) 12 to 25 No. (.75 mm) to 8** 3 to 6 ±8 ±1 ±5 to 12** ±3 ±5 * Select the Job Mix Formula with due regard to the availability of materials and service requirements of project. Test results outside the design range are not prohibited, provided they are within the job mix tolerances. ** Determine by wet sieving. Where local environmental conditions (temperature and availability of free moisture) indicate that in order to prevent damage by frost action it is necessary to have lower percentages passing the No. (.75 mm) sieve than permitted in Table 6, appropriate lower percentages shall be specified. When specified, the material having a diameter smaller than.2 mm shall not exceed 3% mass. CURB PAVER 12 IN. (3 mm) WIDE GEOTEXTILE ALONG PERIMETER. TURN UP AGAINST CURB BEDDING SAND CONCRETE CURB AND GUTTER PER LOCAL STANDARDS WITH 9 DEGREE FACE AGGREGATE BASE DETAIL 'A' CONCRETE PAVER 3 1/8 IN. (8 mm) MIN THICKNESS 12 IN. (3 mm) WIDE GEOTEXTILE ALONG PERIMETER TURN UP AGAINST CURB. SEE DETAIL 'A' WALK / GRASS 1 IN. (25 mm) BEDDING SAND COMPACTED AGGREGATE BASE COMPACTED SOIL SUBGRADE GEOTEXTILE AS REQUIRED DRAIN SURROUNDED BY OPEN-GRADED AGGREGATE AND GEOTEXTILE AS REQUIRED Figure 7: Typical cross section with an unstabilized, dense-graded base Page 8

23 of 1,8 lbf (8 N) per ASTM D5 or AASHTO T-49. Use of the appropriate asphalt (performance grade) cement binder for local climate conditions is also recommended. For example, a state department of transportation Superpave intermediate binder course mix required for interstate or primary roads may be adequate. Cement-treated base material is required to have a minimum 7-day unconfined compressive strength of 6 psi (4.5 MPa) per ASTM D432 and D4219. For constructability purposes, the minimum bound base thickness for design purposes is set at 4 in. ( mm). Figure 8 illustrates a typical cross section with treated bases or an asphalt base and drainage holes. Asphalt bases should conform to typical provincial, state or municipal material and construction specifications for asphalt pavements. This layer does not require a surface riding layer of fine aggregate and consists of coarser aggregates and asphalt cement. The asphalt base layer thicknesses noted in Table 11 vary between 2 in. ( mm) and 8.5 in. (22 mm) depending on traffic, soil category and drainage conditions. Materials Aggregates for subbase are crushed, angular materials typically used in highway construction are generally suitable for interlocking concrete pavement. All bound or treated bases are constructed over 4 to 8 in. ( to mm) unbound dense-graded aggregate base as described above. Unbound subbase materials are required to meet the local state, provincial or municipal standards governing subbase materials. Lo- cal road agencies may also use open-graded subbases for drainage. Where local specifications are unavailable, the subbase is required to meet the gradation requirements according to ASTM D294 noted in Table 6. The required minimum strength of the unbound subbase is a CBR of 4% per ASTM D1883. The required plasticity index is a maximum of 1 and the maximum liquid limit of 25 according to ASTM D4318 and AASHTO T-9. Compaction Requirements Compaction of the subgrade soil during con struction should be at least 95% Standard Proctor Density as tested using AASHTO T-99 or ASTM D 698 for cohesive (clay) soils and at least 95% Modified Proctor density as tested using AASHTO T-18 or ASTM D 1557 for cohesionless (sandy and gravelly) soils. The higher compaction standards described in T-18 or D 1557 are preferred. The effective depth of compaction for all cases should be at least the top 12 in. (3 mm). Soils having an Mr of 4, psi (31 MPa) or less (CBR of 3% or less or R value of 8 or less) should be evaluated for replacement with a higher bearing strength material, installation of an aggregate subbase capping layer, improvement by stabilization or use of geotextiles or geogrids. ATB and CTB density testing should conform to provincial, state or local requirements. In-place density testing of all of the soil subgrade and pavement layers should be included in the project construction specifications and documented with written testing reports. Density tests on the site project as part of construction quality control are critical to pave- CONCRETE CURB CONCRETE PAVER 3 1/8 IN. (8 mm) MIN. THICKNESS 1 IN. (25 mm) BEDDING SAND WOVEN GEOTEXTILE OVER JOINTS AND CTB TURN UP AT CURB (NOT USED ON ATB) ASPHALT-TREATED BASE (ATB), CEMENT-TREATED BASE (CTB), ASPHALT OR CONCRETE BASE COMPACTED AGGREGATE SUBBASE COMPACTED SOIL SUBGRADE Figure 8. Drain detail in treated bases 2 IN. ( MM) DIA. DRAIN HOLE LOCATE AT LOWEST ELEVATIONS AND FILL WITH PEA GRAVEL Page 9

24 Table 7. Recommended Bedding Sand Gradation Gradation for Bedding Sand ASTM C33 Sieve Size CSA A23.1 FA1 Percent Passing Sieve Size Percent Passing 1. mm No. 4 (4.75 mm) 95 to 5. mm 95 to No. 8 (2.36 mm) 8 to 2.5 mm 8 to No. 16 (1.18 mm) to mm to 9 No. 3 (.6 mm) 25 to 6 63 µm 25 to 65 No. (.3 mm) 5 to µm 1 to 35 No. (.15 mm) to 1 16 µm 2 to 1 No. (.75 mm) to 1 8 µm to 1 3/8 in.(9.5 mm) Note: Bedding sands should conform to ASTM C33 or CSA A23.1 FA1 gradations for concrete sand. For ASTM C33, ICPI recommends the additional limitations on the No. (.75 mm) sieve as shown. For CSA A23.1 FA1, ICPI recommends reducing the maximum passing the 8 μm sieve from 3% to 1%. ment performance. Difficult to compact areas can include areas next to curbs, other pavements, and around utility structures. Such areas may require additional compaction or use of manual equipment to achieve specified densities. Structural Contribution of the Concrete Pavers and Bedding Sand Layer Research using accelerated traffic studies and non-destructive structural testing in the United States and overseas has shown that the combined paver and sand layers stiffen while exposed to greater numbers of axle loads. The progressive stiffening that results in lock up generally occurs early in the life of the pavement, before 1, ESALs (Rada 199). Once this number of loads has been applied, Mr = 4, psi (3, MPa) for the combined 3 1/8 in. (8 mm) thick paver and 1 in. (25 mm) of bedding sand. Pavement stiffening and stabilizing can be accelerated by static proof-rolling with an 8 1 ton (8 1 T) rubber tired roller. The above resilient modulus is similar to that of an equivalent thickness of asphalt. The 3 1/8 in. (8 mm) thick pavers and 1 in. (25 mm) thick bedding sand together have an AASHTO layer coefficient at least equal to the same thickness of asphalt, i.e.,.44 per inch (25 mm). This renders an AASHTO Structural Number or SN of in. x.44 = 1.82 for this pavement layer. The recommended Caltrans Gravel Equivalency (GE) for the concrete paver layer = 2 and unlike asphalt the GE for concrete pavers does not decrease with increasing TIs. The modulus or stiffness of the concrete paver layer will not substantially decrease as temperature increases nor will they become brittle in cold climates. The surfacing can withstand loads without distress and deterioration in temperature extremes. Bedding and Joint Sand Selection Bedding sand thickness should be consistent throughout the pavement and not exceed 1 in. (25 mm) after compaction. A thicker sand layer will not provide stability. Very thin sand layers (less than 3/4 in. [2 mm] after compaction) may not produce the locking up action obtained by sand migration upward into the joints during the initial compaction in construction. The bedding layer should conform to the gradation in ASTM C 33, as shown in Table 7. Do not use screenings or stone dust. The sand should be as hard as practically available and the particle shape should be sub-angular. ICPI Tech Spec 17 Bedding Sand Selection for Interlocking Concrete Pavements in Vehicular Applications provides additional information on gradation and test criteria on selecting bedding sands for pavements subject to 1.5 million lifetime ESALs or higher. Joint sand provides vertical interlock and shear transfer of loads. It can be slightly finer than the bedding sand. Gradation for joint material should comply with ASTM C144 or CSA A179 with a maximum % passing the No. 16 (1.18 mm) sieve and no more than 5% passing the No. (.75 mm) sieve. Bedding sand may be used for joint sand. Additional effort in filling the joints during compaction may be required due to its coarser gradation. Concrete Paver Selection Concrete pavers are required to conform to the product requirements of ASTM C936 Standard Specification for Solid Interlocking Paving Units in the United States and CSA A231.2 Precast Concrete Pavers in Canada. For this ASCE standard, pavers must have an aspect ratio (overall length/thickness) less than or equal to 3:1 and a minimum thickness of 3 1/8 in. (8 mm). A 45 or 9-degree herringbone laying pattern is recommended with sailor courses at the perimeter. No less than onethird of a cut paver should be exposed to tire traffic. The designer is advised that alternative laying patterns may be considered as long as they are functionally and structurally equivalent. Other shapes than rectangular pavers can be considered in the design with the responsibility of the design engineer to confirm that the structural capacity is Page 1

25 Table 8. Design Tables for Granular GRANULAR BASE THICKNESSES (mm) (8 % reliability) ESALs (x 1,) Pavement Caltrans Traffic Index Drainage Layer Type Category 1 Category 2 Category 3 Category , 2, 5, 1, (Table continues on p. 12) Page 11

26 Table 8 Continued from p. 11 GRANULAR BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) Pavement Caltrans Traffic Index Drainage Layer Type Category 5 Category 6 Category 7 Category , 2, 5, 1, Page 12

27 Table 9. Design table for asphalt treated base ASPHALT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) Pavement Caltrans Traffic Index Drainage Layer Type Category 1 Category 2 Category , 9. 2, 9.8 5, 1.9 1, 11.8 Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated (Table continues on p. 14) Page 13

28 Table 9 Continued from p. 13 ASPHALT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, 5, 1, Asphalt Treated Asphalt Treated Pavement Caltrans Traffic Index Drainage Layer Type Category 4 Category 5 Category 6 Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Page 14 (Table continues on p. 15)

29 Table 9 Continued from p. 14 ASPHALT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) Pavement Caltrans Traffic Index Drainage Layer Type Category 7 Category , 2, 5, 1, Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Asphalt Treated Page 15

30 Category 3 Category 2 Category 1 Table 1. Design table for cement treated base CEMENT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, Pavement Caltrans Traffic Index Drainage Layer Type Cement Treated Cement Treated Cement Treated Cement Treated Cement Treated Cement Treated Unbound Dense-graded 1 1 Cement Treated Unbound Dense-graded Cement Treated Unbound Dense-graded 1 1 Cement Treated , 1.9 1, (Table continues on p. 17) Page 16

31 Category 6 Category 5 Category 4 Table 1 Continued from p. 16 CEMENT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, Pavement Caltrans Traffic Index Drainage Layer Type Cement Treated Unbound Dense-graded 1 1 Cement Treated Cement Treated Cement Treated 1 1 Cement Treated Cement Treated Cement Treated Cement Treated Cement Treated , 1.9 1, (Table continues on p. 18) Page 17

32 Category 8 Category 7 Table 1 Continued from p. 17 CEMENT TREATED BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, Pavement Caltrans Traffic Index Drainage Layer Type Cement Treated Unbound Dense-graded Cement Treated Cement Treated Cement Treated Cement Treated Cement Treated Page 18 5, 1.9 1,

33 Category 4 Category 3 Category 2 Category 1 Table 11. Design table for asphalt concrete base ASPHALT CONCRETE BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, Pavement Caltrans Traffic Index Drainage Layer Type Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete , 1.9 1, (Table continues on p. 2) Page 19

34 Category 8 Category 7 Category 6 Category 5 Table 11 Continued from p. 19 ASPHALT CONCRETE BASE THICKNESSES (mm) (8% reliability) ESALs (x 1,) 1 2 1, 2, Pavement Caltrans Traffic Index Drainage Layer Type Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Asphalt Concrete Page 2 5, 1.9 1,

35 at least equal to the AASHTO structural number layer coefficient (SN) of the.44 for the pavers and bedding sand layer used in the standard, either by testing or confirmation from the manufacturer. ICPI takes a conservative approach by not recognizing differences among paver shapes with respect to structural and functional performance. Certain manufacturers may have materials and data that discuss the potential benefits of shapes that impact functional and structural performance in vehicular applications. Thickness and Final Pavement Structural Design The required subbase thickness is determined based on the design reliability, design life, estimated traffic, subgrade soil type, pavement structure drainage and base type selected. thicknesses are determined from one of the four design tables. The design tables provide structural design thicknesses primarily for unbound bases (granular base), ATB, and CTB. However, a thickness design table is also provided for asphalt concrete (AC) bases to reduce thick pavement structures associated with high traffic/low subgrade strength conditions. In the development of the AC table, an AASHTO structural layer coefficient of.44 has been assumed for AC. For AC layer coefficients other than.44, the designer is advised to consult the 1993 AASHTO Guide. Tables 8 through 11 show the design tables for unbound granular base, ATB, CTB and AC for 8% reliability factor using the 1993 AASHTO Guide. This reliability factor is slightly higher than the 75% in the ASCE Standard and tables and in some cases can result in slightly thicker subbases, specifically in weak soils. Design Example Design examples are given with good soil conditions (subgrade category 4) and, fair drainage, with lifetime traffic of 5,, ESALs. Designs developed for these conditions are shown in Table 12. Table 12. Material thickness (mm) results for design example Unbound ATB CTB AC Pavers and Bedding ATB n/a n/a n/a CTB n/a n/a n/a AC n/a n/a n/a 11 Unbound Unbound n/a Other Design Considerations and Construction Details Guidance is also provided on proper detailing around utility structures, including edge detailing with sailor and soldier courses. Particular emphasis is given to drainage details for unbound aggregate and treated bases. This benefits pavement life and performance for all structural designs and the details are unique to interlocking concrete pavements as shown in Figures 7 and 8. For further details, design considerations, best practices and maintenance procedures designers are directed to the ICPI Tech Spec series and detail drawings available at The designer is also encouraged to address how interlocking concrete pavement can contribute to sustainability through applying the Leadership in Energy and Environmental Design (LEED ) credit system. Additional information on LEED credits can be found in ICPI Tech Spec 16 Achieving LEED Credits with Segmental Concrete Pavement. Computerized Solutions The preceding design example and most interlocking concrete pavement for parking lots and roads can be designed with Interlocking Concrete Pavement Structural Design Program that uses Excel-based software. The software is based on the ASCE 58-1 design standard and generates thickness solutions for unbound aggregate base, asphaltand cement-treated, and asphalt concrete bases. ICPI Lockpave software is another a computer program for calculating pavement base thicknesses for parking lot, street, industrial, and port applications. User designated inputs include traffic loads, soils, drainage, environmental conditions and a variety of ways for characterizing the strength of pavement materials. Parking lot and street pavement thickness can be calculated using the 1993 AASHTO flexible pavement design procedure (an empirical design method) or a mechanistic, layered elastic analysis that computes projected stresses and strains in the pavement structure modified by empirical factors. Outputs include pavement thickness using different combinations of unbound and bound bases/subbases. thicknesses can be calculated for new construction and for rehabilitated asphalt streets using an overlay of concrete pavers. After a pavement structure has been designed, the user can project life-cycle costs by defining initial and lifetime (maintenance and rehabilitation) cost estimates. Design options with initial and maintenance costs plus discount rates can be examined for selection of an optimal design from a budget standpoint. Sensitivity analysis can be conducted on key cost variables on various base designs. For further information on both software programs, contact ICPI members, ICPI offices or visit the web site Page 21

36 Geosynthetics Geotextiles, geogrids and cellular confinement systems are seeing increased use in pavements. Geotextile selection and use should follow the guidance provided in AASHTO M288. Geotextiles are placed over the top of the compacted soil subgrade and separate the soil from the base materials. These are recommended over silt and clay soils. Geogrids are sometimes used in very soft, wet and slowly draining soils. Cellular confinement systems filled with base materials and placed over the compacted soil subgrade have been used to reduce base thicknesses. Manufacturer s literature should be consulted for guidance on reduction of base thickness given anticipated traffic and soil conditions. Rigid Pavement Design with Interlocking Concrete Pavers Rigid pavements consisting of Portland cement concrete (PCC) slabs distribute loads to the compacted soil subgrade through flexure, or bending action. In such pavements the load spreading is primarily a function of the thickness of the slab and the flexural strength of the PCC. materials are often placed under the slab to provide additional structural support and drainage. When PCC slabs are used as a base under concrete pavers, the structural contribution of the concrete pavers is often ignored by designers. The following sections provide a design method that includes some structural contribution by concrete pavers and bedding materials over PCC slabs as well as over roller compacted concrete. This pavement assembly requires consideration of the bedding materials, prevention of bedding sand loss and avoiding discontinuities over slab joints. Detailing that addresses these aspects are also covered in the following sections. Background to PCC Pavements There are three main types of PCC pavement; jointed concrete pavements (JCP), jointed reinforced concrete pavements (JRCP) and continuously reinforced concrete pavements (CRCP). Although other types are used, this Tech Spec will only address these three PCC systems. The differences among them are primarily in how environmental effects are controlled such as moisture change and temperature changes, including curing and environmental factors. These factors affect the reinforcement and jointing arrangements with little change in the slab thickness. As concrete cures and dries, water in small pores within the cement creates surface tension. This force pulls the pore walls closer together causing the volume of the cement paste to shrink. This action reduces the entire paving slab size slightly. As the slabs are partially restrained by friction from the underlying base or soil subgrade, tensile stresses develop that can result in shrinkage cracks. The stress from shrinkage is proportional to the length of the section of pavement. To control the shrinkage it is therefore necessary to provide joints at sufficiently close centers to keep the shrinkage stresses below the tensile strength of the concrete. Alternatively, reinforcement can be used to increase the tensile strength of the pavement so that greater joint spacing can be used. As concrete pavements heat up the slabs expand, and when they cool the concrete contracts. This movement results in closing and opening of the joints in the pavement. As expansion and contraction are proportional to the length of the slab, the movement range increases with greater joint spacing. Movement is also proportional to the temperature range, so this also requires consideration when designing the joints. Typically concrete can expand or contract by about 1/16 in. (1.5 mm) for every 1 ft (3 m) over an 8 F (27 C) temperature change. Pavement temperatures generally fluctuate over a wider range than air temperatures. Thickness design for PCC pavements for low-speed roads and parking lots is typically done according to the 1993 AASHTO Guide or to local adaptations. Different equations are used for the design of rigid pavements than those for flexible pavements. The thickness of PCC pavements is determined to resist wheel loads imposed by the predicted traffic. Thickness depends on the soil conditions, the type of subbase, the edge conditions, the reliability requirements and the number of 18, lb (8 kn) ESAL repetitions. Some design considerations follow and thickness design is covered in greater detail later. Jointed Concrete Pavement In a jointed concrete pavement (JCP) the joints are placed at relatively close centers so that curing shrinkage does not lead to random cracking, and that joint widths are restricted to acceptable limits. The joints may have load transfer devices such as steel dowel bars (doweled JCP), or the interlocking of the aggregate particles on each face of the joint may be sufficient to transfer the loads from one side of the joint to the other (plain JCP). The joint spacing is dependent upon the thickness of the concrete. A general rule of thumb is that the joint spacing should not exceed thirty times the slab thickness and should in no case exceed 2 ft (6 m). Individual panels should generally have a length of no more than 1.25 times the width. For doweled joints the joint spacings are typically between 1 and 2 ft (3 and 6 m) with joint widths potentially up to 1/8 in. (3 mm). For plain joints, the joint spacings are typically 1 to 15 ft (3 to 4.5 m) with joint widths of up to 1/16 in. (1.5 mm). This type of pavement is the best solution as a base under interlocking concrete pavers. Page 22

37 Jointed Reinforced Concrete Pavement Jointed reinforced concrete pavements are designed with longitudinal and transverse reinforcement to accommodate the tensile stresses that arise during curing. This enables greater joint spacing to be achieved, but results in wider joint opening. As such, aggregate interlock cannot be relied upon and all joints require load transfer devices such as dowels. The reinforcement is typically located at about mid-depth in the slab so it does not increase the load capacity of the concrete section, As such, the same thickness of slab is required as for jointed concrete pavements. Joint spacings are typically 15 to 6 ft (4.5 to 18 m) with joint widths of up to 1/2 in. (13 mm). Intermediate joints are usually included to enable construction activities and to control warping of the slabs. Warping occurs when there is a temperature difference between the top and the bottom of the concrete that causes it to curl. The intermediate joints are typically spaced at 1 to 2 ft (3 to 6 m) and include tie bars to keep the two sides of the joint from moving relative to each other. Large joint spacings can be problematic under pavers as joint movement reflects to the surface resulting in bedding sand loss and localized settlement and loosening of the pavers. Continuously Reinforced Concrete Pavement Continuously reinforced concrete pavements are designed with a greater amount of longitudinal reinforcement so that they can be constructed without transverse joints. The same thickness of slab is required as for jointed concrete pavements as the reinforcement does not increase the load capacity of the pavement. There is a general acceptance that transverse cracking will occur, however, the cracks are held tightly together by the longitudinal reinforcement. The cracks are initially widely spaced, but with full curing, subsequent traffic and temperature changes, the cracks may develop as closely spaced as 2 ft (.6 m). Minor opening and closing of these joints are generally considered to accommodate the expansion and contraction of the pavement. Reinforcement in the transverse direction is generally similar to that in jointed reinforced concrete pavements. Longitudinal joints are constructed in a similar fashion to jointed reinforced concrete pavements. They may have tie bars or dowels depending on the pavement width. Excessive spacing of longitudinal movement joints may result in localized issues with the overlying pavers. Joints As described above, the joints in a concrete pavement control cracking from curing shrinkage and to permit movement caused by moisture and temperature changes. The joints should be located so that they provide adequate load transfer across each from aggregate interlock or from load transfer devices. Joints are typically laid out in a rectangular grid pattern with joints meeting edges of the pavement at no less than 6 degrees. Joints should not dead-end at another joint. They should be detailed to prevent ingress of moisture and infiltration of foreign mater. There are three basic joint types that are formed during pouring or induced shortly afterwards. These are contraction joints, expansion joints and isolation joints. Each are described below and how they should be detailed when under interlocking concrete pavement. Contraction Joints Contraction joints provide a release for tensile stress in the pavement as the concrete contracts during curing. When they are induced in the interior of a pour of concrete they are often referred to as weakened plane joints as they cause a crack to occur in a defined position. In addition to being formed during pouring, weakened plane joints may be induced by early sawing, or by inserting crack-inducing plastic strips. Their placement controls where the tensile failure will occur so that the resulting cracks are in predefined positions, preventing random cracking. They can be oriented in the transverse and longitudinal directions relative to the pavement. The spacing of the joints is determined based upon the materials used, the thickness of the slab and the local environmental conditions, as described above. Load transfer devices are used when the joint opening is too wide to permit aggregate interlock. Contraction joints should be covered with minimum 12 in. (3 mm) wide woven geotextile strips to prevent bedding sand loss under concrete pavers. Expansion Joints Expansion joints perform in the same way as contraction joints but are also used to accommodate any longitudinal or transverse expansion of the pavement that exceeds the drying shrinkage. A compressible filler board absorbs any compressive stresses induced in the concrete by expansion. Where possible, their use is minimized with their most frequent location being at changes in the pavement construction and at intersections or other fixed structures in the pavement surface. In some cases the joint may also need to accommodate lateral movement. Expansion joints should generally be carried through the paver surfacing with the installation of edge restraints on either side. Isolation Joints Isolation joints are used in locations where movements in the pavement are to be isolated from an adjacent feature. They may be used against a building, a utility structure or other feature where vertical and horizontal movement could impose unwanted load into that feature. They are normally formed by including a compressible filler board without any load transfer devices. Isolation joints do not generally experience significant movement and they should Page 23

38 Table 13. Approximate relationships among Mr*, CBR and k-value in pounds per cubic inch (MPa/m) Design Mr, psi (MPa) Design CBR, % Design k-value, pci 3, (2.6) (42) 5, (34.4) (7) 7, (48.2) (98) 1, (68.9) (14) 15, (13.4) (21) 2, (137.8) 25 1,31 (28) 25, (172.3) ,289 (3) 3, (26.8) 47 1,546 (42) * Mr=2,555 x (CBR).64, Mr is in psi Mr=17.61 x (CBR).64, Mr is in MPa be covered with a woven geotextile to prevent bedding sand loss. Roller Compacted Concrete Background Roller compacted concrete (RCC) behaves in a similar fashion to jointed concrete pavement and may be used as an alternative base under interlocking concrete pavement. Fresh RCC consists of a semi-dry concrete spread through a modified asphalt paving machine. PCC aggregates are used in the mix and the final strength is similar paving quality concrete. Mix designs are prepared in the laboratory to determine compressive strength and maximum density. Compressive strengths of 3, to 5, psi (2 to 35 MPa) may be specified. Compaction is initially done by the paving machine and finally by rollers until the target density is achieved. This is typically 98% of modified Proctor density. RCC may be placed without joints, or joints can be induced on a regular grid. When joints are not planned, the roller compacted concrete develops a network of narrow cracks during curing. The curing shrinkage is far less than for PCC pavements so the joints and cracks transfer loads by aggregate interlock. Design thicknesses are similar to those for PCC pavements. Traffic The AASHTO equations for pavement design express serviceability loss as a measure of pavement damage. The damaging effect of axles is different between the flexible and the rigid pavement equations. This is reflected in the AASHTO design method by having a different flexible ESAL values to rigid ESAL values, however the difference is not considered to be significant for design of interlocking concrete pavements over concrete. Soil Subgrade Support The AASHTO design method for rigid pavements uses the soil subgrade property known as the Modulus of Subgrade Reaction or k-value. This value is determined using a plate load test that is different than those described above in the flexible pavement section. The test is described in ASTM D1194 or AASHTO T-235. It involves placing a 3 in. (.76 m) diameter rigid plate on the subgrade and measuring the deflection of the soil as the load on the plate is gradually increased. The k-value is determined as the pressure divided by the deflection at during certain points in the test. The test is rarely carried out and alternative means are generally used to establish the design value. The design k-value is considered at the underside of the concrete, and includes the effects of any subbase layers. The AASHTO method also includes seasonal changes of subgrade strength and the proximity of rock to the surface to develop a composite k-value for design. This provides a wide range of k-values although the designed thickness has low sensitivity to this property. As such, the design charts in this Tech Spec are simplified to use an approximate relationship between the design resilient modulus (Mr) and the k-value. The design values are listed in Table 13. The values stated assume no subbase is present and that the depth to a rigid rock layer exceeds 1 ft (3 m). Where soils are known to be prone to pumping under concrete pavements, a minimum of 4 in. ( mm) of compacted aggregate subbase material over the subgrade is recommended prior to casting the concrete. This thickness is also recommended with soils with an Mr < 7, psi (48 MPa) or CBR < 5%. Pavement Materials Most states, provinces and municipalities have material and construction standards for concrete pavements. However, material requirements vary among jurisdictions, particularly regarding material strengths. The design tables on the following pages presenting the rigid pavement base layer thicknesses are based upon typical values encountered in many standards. There are two properties used in the AASHTO design method to characterize PCC pavements; flexural strength and the elastic modulus. Typically pavement quality concrete is specified with a flexural strength, although compressive strength is occasionally substituted. The flexural strength should be determined using beam specimens loaded at third points as described in ASTM C78 or AASHTO T-97. If compressive strength is the only requirement available, the designer can use Table 14 to provide an approximate correlation. The elastic modulus of concrete is rarely specified and so typical relationships to flexural or compressive Page 24

39 strengths are required and are provided in Table 14. The AASHTO design equation is based upon the average value of flexural strength, which will be slightly higher than the specified value. When PCC is used as a base under concrete pavers it is usually not necessary to include an air entraining agent. The pavers provide protection against damage from frost action. Reinforcement is not considered in the AASHTO design equation for determining the PCC pavement thickness. However, the type of reinforcement is important in determining the required bar sizes and centers and the spacing of joints. Typically, reinforcing bars and tie bars are Grade 6 deformed bars in size numbers #4, #5 or #6. However, Grade 4 steel may be used. As jointed concrete pavement is the preferred base condition, no additional guidelines are provided for determining the size and spacing of reinforcement. Dowel bars are typically Grade 6 in sizes ranging from 1/2 to 11/4 in. (13 to 32 mm). Table 15 sets out typical recommendations for dowel bars recommended by the American Concrete Institute. All dowel spacings are 12 in. (3 mm) on center. Joint filler board is used in expansion joints and isolation joint to absorb any compression as the adjacent slabs move or expand. There are several different types including foam and bitumen impregnated fiber board. The thickness is selected dependent on the anticipated movement. Joint sealant is used to prevent the ingress of moisture and intrusion of foreign matter into joints. It may not be required on all joints when the concrete is exposed at the surface of the pavement if the movement range is small and if the lower layers are not moisture susceptible. When jointed concrete pavement is used under pavers the sealant may be left off if the joints are covered by geotextile. Sealant is recommended for joints with wider spacings. Table 14. Approximate correlations among flexural strength, compressive strength and elastic modulus Flexural Strength, psi (MPa) 5 (3.8) Compressive Strength, psi (MPa) Elastic Modulus, psi (MPa) 3, (2) 3,7, (25,517) Woven geotextiles are recommended to cover the joints and cracks in the PCC base to prevent bedding sand loss. Since they are manufactured from plastics such as polypropylene and polyester, the materials are stable and resistant to many chemicals encountered in the ground, and also to the deteriorating effects of sunlight. Woven geotextiles are preferred for use directly under the bedding sand as they maintain their integrity under loads exerting abrasion on the concrete. The important property in geotextiles for preventing sand loss is the apparent opening size or AOS. Woven geotextiles with an apparent opening size of.3 mm to.6 mm are generally suitable. As noted earlier geotextiles are applied to joints in minimum 12 in. (3 mm) wide strips. Structural Design Procedure The following structural design procedure is for roads and parking lots. PCC pavements are designed using a simplified version of the method in the AASHTO 1993 Guide. These pavement sections were then analyzed using mechanistic analysis to determine the critical stresses. The pavements were also analyzed considering a concrete paver surface to distribute the loads to a larger area on top of the concrete. The pavements were reduced in thickness incrementally until the same critical stresses were achieved in the concrete. The results of the analyses are presented in the tables. All designs are minimum 3 1/8 (8 mm) thick concrete pavers in a herringbone pattern. Bedding materials are sand or sand-asphalt (bitumen-setting bed). ICPI Tech Spec 17 Bedding Sand Selection for Interlocking Concrete Pavements in Vehicular Applications provides guidance on testing and selecting bedding sands. Table 15. PCC slab thickness and dowel characteristics Slab Thickness, in. (mm) Dowel Diameter, in. (mm) Dowel Length, in. (mm) 4 and 41/2 ( and 115) 1/2 (13) 12 (3) 5 and 51/2 (13 and 14) 5/8 (16) 12 (3) 6 and 61/2 (1 and 165) 3/4 (19) 14 (3) 7 and 71/2 ( and 19) 7/8 (22) 14 (3) 59 (4.1) 3, (24) 4,, (27,586) 63 (4.3) 4, (28) 4,2, (29,31) 67 (4.6) 4, (31) 4,, (31,34) 8 and 81/2 ( and 215) 1 (25) 14 (3) 7 (4.8) 5, (35) 4,7, (32,414) 9 and 91/2 (23 and 24) 11/8 (32) 16 (4) 1 and 11/2 (2 and 265) 11/2 (38) 16 (4) Page 25

40 Table 16. PCC base thicknesses under interlocking concrete pavement for a 3, psi (2 MPa) or 5 psi (3.8 MPa) flexural strength cement base. PCC Thickness 3, psi (2 MPa) compressive or 5 psi (3.8 MPa) flexural strength ESALs (x1,) 1 2 1, 2, 5, 1, Caltrans Traffic Index , (26) , (172) , (137) , (13) , (68) , (48) , (34) , (21) Subgrade Mr psi (MPa) Table 17. PCC base thicknesses under interlocking concrete pavement for a 4, psi (27.5 MPa) or 63 psi (4.3 MPa) flexural strength concrete base PCC Thickness 4, psi (27.5 MPa) compressive or 63 psi (4.3 MPa) flexural strength ESALs (x1,) 1 2 1, 2, 5, 1, Caltrans Traffic Index , (26) , (172) , (137) , (13) , (68) , (48) , (34) , (21) Subgrade Mr psi (MPa) Page 26

41 Table 18. PCC base thicknesses under interlocking concrete pavement for a 5, psi (34 MPa) or 7 psi (5 MPa) flexural strength concrete base PCC Thickness - 5, psi (34 MPa) compressive or 7 psi (5 MPa) flexural strength ESALs (x1,) 1 2 1, 2, 5, 1, Caltrans Traffic Index , (26) , (172) , (137) , (13) , (68) , (48) , (34) , (21) Subgrade Mr psi (MPa) Structural Design Tables Tables 16, 17, and 18 establish the PCC base thickness design solutions. Depending on the soil subgrade strength (Mr) and ESALs. The recommended minimum thickness of PCC base is 4 in. ( mm) at and below 1,, ESALs, and 5 in. (125 mm) above 1,, ESALs. Use the following steps to determine a pavement thickness: 1. Compute design ESALs or convert computed TIs to design ESALs or use the recommended default values given in Table 1 as for flexible base design. 2. Characterize the soil subgrade strength from laboratory test data. If there is no laboratory or field test data, use Tables 3, 4 and 5 to estimate Mr. 3. Select the appropriate table (16, 17 or 18) depending on the compressive strength of the concrete base. 4. Determine the required PCC base thickness. Use Mr for design subgrade strength and design ESALs in the selected tables. Example Solution and Results For a given site where the soils are ML, it is assumed that an aggregate subbase will be used to provide a working platform and to protect the pavement from pumping related distress. 1. Estimate design load: 84, ESAL. Interpolate between, and conservatively select 1,, when using Tables 16, 17 or Characterize subgrade Mr: 4, psi (31 MPa) from previous example. Conservatively select 5, psi (35 MPa) on Tables 16, 17 or Determine concrete strength: Consider 3, psi (21 MPa) and 4, psi (27.5 MPa) options on Tables 16 and Determine base thickness requirements: the thickness required for 3, psi (2 MPa) concrete is 5 in. (125 mm) and for 4, psi (28 MPa) concrete is 41/2 in. (115 mm). The final cross section design is shown in Figure 9 on page 28 with 31/8 in. (8 mm) thick concrete pavers and a 1 in. (25 mm) thick bedding sand layer over 41/2 in. (115 mm) of 4, psi (27.5 MPa) PCC base and 4 in. ( mm) compacted aggregate subbase since the soil Mr < 7, psi (48.2 MPa) which is CBR < 5%. Additionally, the concrete slab is jointed at 1 ft (3 m) centers and dowels are 1/2 in. (13 mm) diameter. The joints will be covered with a strip of woven geotextile, minimum 12 in. (3 mm) wide, to prevent bedding sand loss. Page 27

42 CONCRETE CURB CONCRETE PAVER 3 1/8 IN. (8 MM) MIN. THICKNESS 1 IN. (25 MM) BEDDING SAND WOVEN GEOTEXTILE OVER JOINTS 4 1/2 IN. (115 MM) THICK 4, PSI (27.5 MPa) CONCRETE BASE MIN. 4 IN. ( MM) THICK COMPACTED AGGREGATE SUBBASE OVER SUBGRADE CBR <5% COMPACTED SOIL SUBGRADE 2 IN. ( MM) DIA. DRAIN HOLE LOCATE AT LOWEST ELEVATIONS AND FILL WITH PEA GRAVEL, MIN. 1 FT (3 M) SPACING NOTES: DRAIN BEDDING SAND OF EXCESS MOISTURE THROUGH PAVEMENT AT LOWEST POINTS AS SHOWN OR AT CATCH BASIN(S). PROVIDE 1" (25 MM) HORIZONTAL DRAIN HOLES IN CATCH BASINS. BOTTOM OF HOLES TO BE EVEN WITH SURFACE OF EXISTING PAVEMENT. COVER HOLES WITH GEOTEXTILE. DO NOT PROVIDE DRAIN HOLES TO SUBGRADE WHEN WATER TABLE IS LESS THAN 2 FT. (.6 M) FROM TOP OF SOIL SUBGRADE. PROVIDE DRAIN HOLES TO CATCH BASINS. Figure 9. Interlocking concrete pavers on a concrete base design example solution. References AASHTO American Association of State Highway and Transportation Officials, Guide for Design of Pavement Structures, Washington, D.C., USA. ASCE 21. American Society of Civil Engineers, Structural Design of Interlocking Concrete Pavement for Municipal Streets and Roadways. ASCE/T&DI 58-1, Reston, Virginia, USA. Rada 199. Rada, G.R., Smith, D.R., Miller, J.S., and Witczak, M.W., Structural Design of Concrete Block Pavements, American Society of Civil Engineers Journal of Transportation Engineering, Vol. 116, No. 5, September/October. Shackel 1979.Shackel, B., A Pilot Study of the Performance of Block Paving Under Traffic Using a Heavy Vehicle Simulator, Proceedings of a Symposium on Precast Concrete Paving Block, Johannesburg, South Africa. Shackel 198. Shackel, B., An Experimental Investigation of the Roles of the Bedding and Joint Sand in the Performance of Interlocking Concrete Block Pavements, Concrete/Beton, No. 19. Shackel 198. Shackel, B. Loading and Accelerated Trafficking Tests on Three Prototype Heavy-Duty Industrial Block Pavements, National Institute for Transport and Road Research, CSIR, Pretoria, South Africa, Technical Report 12. Figures 5 and 6, Tables 5, 6 and 7 are copyright 21 ASCE. Used with permission. Interlocking Concrete Pavement Institute Park Center Road, Suite 27 Herndon, VA 2171 Tel: (73) Fax: (73) ICPI@icpi.org Web: In Canada: P.O. Box 11 Uxbridge, ON L9P 1N4 Canada The content of ICPI Tech Spec technical bulletins is intended for use only as a guideline. It is not intended for use or reliance upon as an industry standard, certification or as a specification. ICPI makes no promises, representations or warranties of any kind, expressed or implied, as to the content of the Tech Spec Technical Bulletins and disclaims any liability for damages resulting from the use of Tech Spec Technical Bulletins. Professional assistance should be sought with respect to the design, specifications and construction of each project. Page 28