SECTION 03100: CONCRETE FORMWORK

Transcription

1 SECTION 03100: CONCRETE FORMWORK PART 1 GENERAL 1.01 GENERAL REQUIREMENTS: A. The drawings describe the extent of the concrete work for the project. This section describes the formwork for concrete, which is not shown on the drawings RELATED DOCUMENTS: A. Document A20 1: General Conditions of the Contract for Construction. B. Section 01340: Shop Drawings, Product Data and Samples. C. Section 03200: Concrete Reinforcement. D. Section 03300: Cast-in-place Concrete QUALITY ASSURANCE: A. Conform to: 1. ACI 347 latest edition, "Recommended Practices for Concrete Formwork." 2. ACI 318 "Building Code Requirements for Reinforced Concrete." 3. ACI 301 "Structural Concrete for Buildings." 4. PS 1 "Construction and Industrial Plywood." B. Forms and formwork are subject to inspection and approval by the Architect. Notify the Architect prior to placing concrete. Badly damaged or improperly installed formwork will be rejected and shall be replaced. PART 2 PRODUCTS A. Wood Forms: Unexposed concrete surfaces: No. 2 common or better. Exposed concrete surfaces: New plywood linings or new plywood forming. Used plywood in good condition may be utilized if approved by Architect. B. Metal forms: Capable of shaping concrete to required dimensions. Without undue dents and deformations and as approved by Architect. C. Form Oil: Non-staining mineral oil. D. Form ties: Comnmercial product, length as required, fixed or adjustable type manufactured to leave no steel within 1 inch of surface of concrete after removal. PART 3 EXECUTION 3.01 INSTALLATION: A. Work sequence: Cooperate with other trades so that all necessary insert, sleeves, anchors, and other miscellaneous embedded metal items are properly installed prior to placement of concrete. Sec Concrete Formworkpage I

2 B. Install in accordance with the latest edition of ACI 347. C. Construct forms to give shapes and dimensions indicated within the tolerances specified in ACl 347 and to give resultant sharp, true lines to exact intent of design indicated or detailed. D. Install forms tight, rigid and adequately braced to prevent deformation under load. E. Chamfer exposed corners and edges to 3/4 inch or as indicated on the drawings. F. Form all vertical surfaces including sides of footings except inside faces of turned down slabs on grade. Hold a straight, true vertical surface. G. Do not use any form treatments containing ingredients that may stain or otherwise injure the concrete or prevent a good bond for subsequent coatings, if any. Keep all forms thoroughly clean H. Ensure that tie holes are patched within 12 hours of form removal. Patching is specified in Section L. Ensure that all concrete inserts are properly placed and securely anchored against displacement during pour REMOVAL OF FORMS: A. General: 1. Obtain Architect's approval before removal. 2. Remove forms with care, in a manner that will not jeopardize the safety of the structure. 3. Damage caused by premature and/or unauthorized removal shall be corrected and repaired at Contractor's expense using methods and materials to be approved by the Architect. B. Non-Supportive Formwork: 1. Formwork not supporting weight of concrete, such as sides of slabs, beams, walls, columns and similar parts of the work may be removed 48 hours after placing concrete, provided concrete is sufficiently hard to not be damaged by form removal operations, and provided curing and protection operations are maintained. C. Supportive Formwork: 1. Formwork supporting weight of concrete, such as beam soffits, joints, slabs and other structural elements may not be removed in less than 14 days or until concrete has attained specified minimum 28 day compressive strength. Determine potential compressive strength of in place concrete by testing field-cured specimens representative of concrete location or members. D. Form Facing Material: 1. Form facing material may be removed 4 days after placement, only if shores and other Sec Concrete Formworkpage 2

3 vertical supports have been arranged to permit removal of form facing material without loosening or disturbing shores and supports FIELD INSPECTION: A. Notify Architect and request field inspection and approval 48 hours in advance for the following: 1. Form installation. 2. Placement of steel and inserts. 3. Form removal. B. Do not proceed with next phase until Architect's approval has been obtained in each case. END OF SECTION Sec Concrete Formwork-page 3

4 SECTION 03200: CONCRETE REINFORCEMENT PART 1 GENERAL 1.01 GENERAL REQUIREMENTS: A. The work includes fabrication and placement of reinforcement for precast and cast-in-place concrete, including deformed bars, welded wire fabric, ties and supports RELATED REQUIREMENTS: A. Document A201: General Conditions of the Contract for Construction. B. Section 01340: Shop Drawings, Product Data and Samples. C. Section 03100: Concrete Formwork. D. Section 03300: Cast-in-Place Concrete QUALITY ASSURANCE: A. Comply with the following Codes and Standards: 1. American Concrete Institute, ACI 315."Manual of Details and Detailing of Concrete Reinforcement" for Detailing Reinforced Concrete Structures. 2. American Concrete Institute, ACI 318 "Building Code Requirements for Reinforced Concrete." 3. American Welding Society, AWS D1.4 "Structural Welding Code - Reinforcing Steel". 4. Concrete Reinforcing Steel Institute, "Manual of Standard Practice" and "Placing Reinforcing Bars". 5. American Society for Testing and Materials (ASTM): ASTM standard specifications and methods are referred to in the following paragraphs by their serial numbers as applicable. 6. Comply with local building code requirements if more stringent than the above SUBMITTALS: A. General: Comply with requirements of Section 01340, Shop Drawings, Product Data and Samples. B. Shop Drawings: Show fabrication, bending and placement of concrete reinforcement. Comply with ACI 315 recommendations showing bar schedules, stirrup spacing, diagrams of bent bars, arrangements and assemblies, as required for the fabrication and placement of concrete reinforcement. Include special reinforcement required at openings through concrete structures PRODUCT DELIVERY, HANDLING AND STORAGE: A. Deliver reinforcement to the project site bundled, tagged and marked. Use tags indicating bar size, lengths and other information corresponding to marking shown on placement diagrams. B. Store concrete reinforcement materials at the site to prevent damage and accumulation of dirt or excessive rust. Sec Concrete Reinforcement page 1

5 PART 2 PRODUCTS 2.01 MATERIALS: A. Reinforcing Bars: ASTM A-615, deformed, Grade 60 except that Grade 40 may be used for stirrups and ties at the contractor's option. B. Steel Wire: ASTM A-82. C. Welded Fire Fabric: ASTM-l 85, flat sheets D. Supports for reinforcement: Provide bolsters, chairs, spacers, and other devices for spacing, supporting and fastening reinforcement in place. Use wire bar type supports complying with the Bar Support Specification contained in the CRSI Manual of Standard Practice. Do not use wood, brick, stone or other unacceptable materials. 1. For slabs on grade, use supports with sand plates or horizontal runners where wetted base materials will not support chair legs. 2. For exposed-to-view concrete surfaces, where legs of supports are in contact with forms, and for sandblasted or bush-hammered concrete provide supports with legs which are plastic protected (CRSI Class 1 protection) or- which have stainless steel tips (CRSI Class 2 protection). 3. Over waterproof membranes, use precast concrete chairs to prevent penetration of the membrane. PART 3 EXECUTION 3.01 FABRICATION: A. General: Shop-fabricate reinforcing bars to conform to required shapes and dimensions, with fabrication tolerances complying with ACI 315. In case of fabricating errors do not re-bend or straighten reinforcement in a manner that will injure or weaken the material. B. Unacceptable Materials: Reinforcement with any of the following defects will not be permitted in the work. 1. Bar lengths, depths and bends exceeding specified fabrication tolerances. 2. Bends or kinks not indicated on drawings or final shop drawings. 3. Bars with reduced cross-section due to excessive rusting or other cause INSTALLATION: A- Examine the substrate and the conditions under which concrete reinforcement is to be installed and notify Architect in writing of unsatisfactory conditions. Do not proceed with the work until unsatisfactory conditions have been corrected. B. Refer to specified codes and standards and Concrete Reinforcing Steel Institute recommended practice for "Placing Reinforcing Bars," for details and methods of reinforcement placement and supports, and as herein specified except as shown on the drawings. Sect Concrete Reinforcementpage 2

6 C. Clean reinforcement to remove loose rust and mill scale, earth, ice and other materials which may impair bond with concrete. D. Position, support and secure reinforcement against displacement by formwork, construction or concrete placement operations. Locate and support reinforcing by metal chairs, runner, bolsters, spacers and hangers, as required and to provide clearances indicated on drawings. E. Place reinforcement at the positions required to obtain the required concrete coverage within the tolerances specified in ACI 315 or as shown on the drawings. Arrange, space and securely tie bars and bar supports together with 16 gauge wire to hold reinforcement accurately in position during concrete placement operations. Set wire ties so that ends are directly away from exposed concrete surfaces. F. Install welded wire fabric in lengths as long as practicable. Lap adjoining pieces at least one-and-one-half full meshes and lace splices with 16 gage wire. Do not make end laps midway between supporting beams, or directly above beams of continuous structures. Offset end laps in adjacent widths to prevent continuous laps. G. Provide sufficient number of supports with strength adequate to carry reinforcement. Do not place reinforcing bars more than 2 in. beyond the last leg of any continuous bar support. Do not use supports as bases for runways for concrete conveying equipment and similar construction loads. H. Maintain continuity of reinforcing by lap splicing reinforcing in accordance with ACI 31 8 subject to the requirement shown on the drawings. Unless larger lap lengths are required, use Class B tension lap splices as defined in ACI 318. I. Do not field weld without the written prior approval of the Architect. If field welding of reinforcement is approved, comply with the requirements of AWS D 1.4 for field welding. Prior to field welding, determine the suitability of the reinforcing bars by a laboratory chemical analysis of the steel. Only steel conforming to the chemical requirements specified in AWS D1.4 may be weldedc END OF SECTION Sec Concrete Reinforcement page 3

7 SECTION 03300: CAST IN PLACE CONCRETE PART 1 GENERAL 1.01 GENERAL REQUIREMENTS: A. Cast in Place Concrete includes sidewalks, drainage structures, building structures, pavement curbs and gutters, and any other portion of the work, which is identified on the drawings as concrete or cast in place concrete. This section does not apply to grout for masonry RELATED REQUIREMENTS: A. Document A201: General Conditions of the Contract for Construction. B. Section 01340: Shop Drawings, Product Data and Samples. C. Section 01410: Testing Laboratory Services. D. Section 03100: Concrete Fonnwork. E. Section 03200: Concrete Reinforcement QUALITY ASSURANCE: A. Comply with provisions of the latest editions of the following codes, specifications and standards, except as otherwise shown or specified: 1. ACI 301 "Specifications for Structural Concrete for Buildings." 2. ACI 311 "Recommended Practice for Concrete Inspection." 3. ACI 318 "Building Code Requirements for Reinforced Concrete." 4. ACI 347 "Recommended Practice for Concrete Formwork." 5. ACI 304 "Recommended Practice for Measuring, Mixing, Transporting and Placing Concrete." 6. Concrete Reinforcing Steel Institute, "Manual of Standard Practice." 7. ASTM Standard Specifications and Methods: Referred to as appropriate in the following paragraphs. 8. Comply with local building code requirements if more stringent than the above. B. Remove and replace concrete work which does not conform to the specified requirements, including strength, tolerances, finishes and color. The Architect will be the sole judge as to the acceptability and appearance of concrete exposed to view. C. Concrete Testing Service: 1. Employ a testing laboratory acceptable to Architect to perform material evaluation tests and to design concrete mixes. 2. Test aggregates by the methods of sampling and testing of ASTM C For portland cement, sample the cement and determine the properties by the methods of test of ASTM C 150. Submit written reports to the Architect, for each material sampled and tested, prior to the start of work. Provide the project identification name and number, date of report, name of concrete testing service, name of contractor, source of concrete aggregates, material manufacturer and brand name for manufactured materials, values specified in the Sec Cast-in-Place Concrete page 1

8 referenced specification for each material and test results. Indicate whether or not material is acceptable for intended use. 4. Certificates of material properties and compliance with specified requirements may be submitted in lieu of testing, when acceptable to the Architect. Certificates of compliance must be signed by the materials producer and the Contractor. 5. Quality Control Testing during Construction: Concrete shall be sampled and tested for quality control during the placement of concrete, as follows: a. Sampling Fresh Concrete: ASTM C 172, except modified for slump to comply with ASTM C 94. b. Slump: ASTM C 143; one test for each concrete load at point of discharge; and one for each set of compressive strength test specimens. If water is added to concrete on site, slump test shall be made after water is added. c. Air Content: ASTM C 231, pressure method; one for each set of compressive strength test specimens. d. Compressive Strength Test: Test specimens shall be molded and cured in accordance with ASTM C-3 1 and tested in accordance with ASTM C-39. Except as otherwise approved by the Architect, test specimens shall be standard cylinders 6" in diameter and 12" in length. One set of 6 specimens shall be made for each 50 cubic yards or fraction thereof of each class of concrete placed in any one day and/or for each 5,000 square feet or less of slab area placed in any one day, and for each six drilled caissons. Two specimens of each set shall be tested at 7 days after molding, and two at 28 days. If the average strength of the 28 day test meets or exceeds the required 28 day strength and if neither specimen has a strength less than 500 psi less than the specified 28 day strength, the final specimens may be discarded. Otherwise, the final specimen shall be retained for possible future testing. Test specimens shall be stored and cured in the field. e. Concrete Temperature: Test hourly when air temperature is 40 degrees Fahrenheit and below, and when 80 degrees Fahrenheit and above; and each time a set of compression test specimens is made. f. Report test results in writing to the Architect within 48 hours of testing. Reports of compressive strength tests shall contain the project identification name and number, date of concrete placement, name of contractor, name of concrete supplier and truck number, name of concrete testing service, concrete type and class, location of concrete batch in the structure, design compressive strength at 28 days, concrete mix proportions and materials, compressive breaking strength and type of break for 7 day, 28 day, or later tests. g. If the average strength of five (5) consecutive 28 day cylinder tests fall below the required compressive strength, the in-place concrete represented by the defective cylinders shall be tested at the Contractor's expense by one of the following methods as directed by the Architect: 1. Core Drilling: ASTM C-42, "Standard Methods of Obtaining and Testing Drilled Cores and Sawed Beams in Concrete". 2. Load Testing: Perform load tests in accordance with the applicable provisions of the latest edition of ACI 318 and as modified by the International Building Code (IBC). D. When approved laboratory 28-day molded conrelte cyllllder tests, together -wlul supplemlentna core tests of in- place concrete, fail to meet the specified strength requirements, then structural calculations and other investigations shall be made by the Architect to determine if such low test Sec Cast-in-Place Concrete page 2

9 concrete may be used in its present condition. The cost for this additional analysis shall be at the contractor's expense on a time and materials basis. Should the low strength concrete be determined unacceptable, the Contractor shall be required to remove and replace the unacceptable concrete to the satisfaction of the Architect at no additional cost to the Owner SUBMITTALS: A- Concrete Mix Designs: Submit certification of concrete mix designs prepared by an approved independent testing laboratory. Mix designs shall be approved prior to placing any concrete. B. Compressive Strength Tests: Deliver 4 copies of compressive strength test reports directly to Architect and one copy to the Structural Engineer for each prescribed test. Each report shall indicate the design mix, admixtures, amount of entrained air, slump, temperature of concrete, ambient temperature, and location of placement of concrete. Initial cylinder tests shall be approved prior to placing concrete. C. Slump Tests: Deliver 2 copies of slump test report directly to Architect, within 48 hours of testing. D. Batch Plant Tickets: 1. Include the following information: a. Location and time of pour. b. Weight of all materials used including aggregates, water, cement, and admixtures. c. Moisture corrections that have been made for moisture present in the aggregates. d. Mix design identification. e. A tabulation of the amount of any water added to the concrete at the job site. Maximum amount of water to be added to any truck is 10 gallons. The signature of the General Contractor's authorized representative must be on all tickets, indicating that he authorized the addition of water, or that water was not added. 2. Submit batch plant tickets to the Architect, within 48 hours of concrete delivery. PART 2 PRODUCTS 2.01 MATERIALS: A. Portland Cement: 1. ASTM C 150, Type I/II, unless otherwise acceptable to the Architect. Type III (high early strength cement) shall not be used without prior written approval. B. Aggregates: L ASTM C 33, and as herein specified. Provided aggregates from a single source for all Sec Cast-in-Place Concrete page 3

10 exposed concrete. Sandstone aggregates shall not be accepted. 2- Fine Aggregate shall be clean, sharp, natural sand free from loam, clay, lumps or other deleterious substances. 3. Coarse Aggregate shall be clean, uncoated, processed aggregate containing no clay, mud, loam or foreign matter, as follows: a. Crushed stone, processed from natural rock or stone. b. Gravel, either natural or crushed. Use of pit or bank run gravel is not permitted. c. Maximum Aggregate Size: C. Water: Potable. Footings: 1-1/2" (size 467) Walls and Beams: 3/4" (size 67) Topping slabs: 1/2" (size 7) D. Fly Ash: ASTM C6 18, Class C. Mix must contain between 20 to 25% fly ash by weight. E. Admixtures: 1 Calcium chloride and other anti-freeze agents are prohibited. 2. Air-Entraining agents: Conform to ASTM C High range water reducing agents: Conform to ASTM C 494, Type A. These products may be used only to increase slump of concrete and not to reduce amount of portland cement required. 4. Other admixtures may be used only with the written prior approval of the Architect. Their inclusion on a proposed mix design does not constitute a request for prior approval RELATED MATERIALS: A. Water stops: Provide flat, dumbbell type or center bulb type water stops at joints as shown on the drawings. Size to suit joints. Provide either rubber or PVC water stops. B. Preformed Expansion Joint Fillers: ASTM D C. Under slab Membrane Waterproofing: Install where required on drawings; see related sections of these specifications. D Joints: 1. Construction Joints: Locate and install construction joints, so as not to impair the strength and appearance of the structure, at locations acceptable to the Architect. a. For Slabs-on-grade, Provide metal key type construction joints where indicated or under partitions. Final placement shall be approved by Architect before placing concrete. Joint depth shall be 4" greater than thickness of slab. Slope bottom of slab to bottom of joint in a distance of 24" either side of joint. b. Provide key ways at least I 1in. deep 1in all construction joints i1 wals, band bet-ween, walls and footings. c. Place construction joints perpendicular to the main reinforcement. Continue all reinforcement across construction joints. Sec Cast-in-Place Concrete page 4

11 2. Isolation Joints in Slabs-On-Grade: Construct isolation joint in slabs on grade at all points of contact between slabs, ground and vertical surfaces, such as column pedestals, foundation walls, grade beams and elsewhere as indicated with the use of 90# felt paper. 3. Control Joints in Slabs-On-Grade: Construct control joints in slabs on grade to form panels of patterns as shown on drawings. a. Use saw cut joints by sawing a continuous slot to a depth of one-fifth the thickness of the slab (but not less than one inch) to form a weakened plane below which a crack will form. Use a power saw with a suitable masonry cutting blade as soon as possible after the concrete has hardened. Joints shall be cut true. Seal saw cut with polyurethane sealant. 4. Expansion Joints: In concrete sidewalks, curbs, pavement gutters, and drive pads, provide 1/2 inch expansion joints at approximately 16 ft. o.c. Exact pattern of joints shall be approved by Architect's representative at the job site. All sidewalks, curbs and gutter and drive pads shall conform to requirements of applicable local ordinances. Unless indicated otherwise on drawings, provide tooled joints at 48 in. o.c. each way maximum between control joints. Cross-slope all walks 1/4" per foot minimum out from building PROPORTIONING AND DESIGN OF MIXES: A. Prepare design mixes for each type of concrete on the basis of water/cement ratio for cured strength at 28 days in strengths noted on the drawings. Use an independent testing facility acceptable to the Architect for preparing and reporting proposed mix designs B. Proportion mixes by laboratory trial batch method as specified in ACI 301 using materials to be employed on the project for each class of concrete required. C. Submit written reports to the Architect for each proposed mix for each class of concrete at least 15 days prior to start of work. Do not begin concrete production until mixes have been reviewed by the Architect. D. Adjustment to Concrete Mixes: Mix design adjustments may be requested by the Contractor when characteristics of material, job conditions, weather, test results or other circumstances warrant; at no additional cost to the Owner and as accepted by the Architect. Laboratory test data for revised mix designs and strength results must be submitted to and accepted by the Architect before using in the work. E. Compressive strengths and Cement Contents; Design mixes to produce concrete of the minimum strengths specified below for the various usages. USAGE STRENGTH CEMENT CONTENT Footings, Stem Walls,Topping Slabs 3,000 psi 480 pcy Exterior Concrete, Slabs-on-grade 3,000 psi 480 pcy Beams, Columns 3,500 psi 500 pcy F. Air-Entrainment: Use air-entraining admixtures in all concrete for exterior sidewalks, stairs, slabs, pads, curbs and gutters and hydraulic structures, unless otherwise shown or specified. Add air- entraining admixture at the manufacturer's prescribed rate to result in concrete at the point of placement having air content within the following limits: Sec Cast-in-Place Concrete page 5

12 1. Concrete structures and slabs exposed to freezing and thawing or subjected to hydraulic pressure use 5% to 8% for maximum 3/4 inch aggregate and from 3% to 6% for maximum 1-1/2 inch aggregate. G. Slump Limits: Proportion and design mixes to result in concrete slump at the point of placement as follows: 1. Ramps and Sloping Surfaces: Not more than 3 in. 2. Reinforced Foundation Systems: Not less than 2 in. and not more than 4 in. 3. All Other Concrete: Not less than 2 in. and not more than 4 in. 4. Above slump limits are for concrete mixes designed without high range water reducing agents (super plasticizers) CONCRETE MIXING: A. On-Site Batch Plant: 1. At Contractor's option, a concrete batch plant may be utilized for site mixing of concrete. Comply with applicable provisions of ACI 301 Manual of Practice. 2. Size batch plant to needs of project. Capable of handling each day's pour without detriment to project schedules. 3. Mix materials for concrete in an acceptable drum type batch machine mixer. For mixers of one cubic yard, or smaller capacity, continue mixing at least 1-1/2 minutes, but not more than 5 minutes after all ingredients are in the mixer, before any part of the batch is released. For mixers of capacity larger than one cubic yard, increase the minimum 1-1/2 minutes of mixing time by 15 seconds for each additional cubic yard, or fraction thereof Provide batch tickets containing the information described in Paragraph 1.04 of this Section. B. Ready-Mixed Concrete: 1. Comply with the requirements of ASTM C 94, and as herein specified. Coloring agent (when color is specified) shall be integral with concrete. 2. Addition of water will not be permitted, except as otherwise specified. 3. When the air temperature is between 85 degrees F. and 90 degrees F., reduce the mixing and delivery time from 1-1/2 hours to 75 minutes, and when the air temperature is above 90 degrees F., reduce the mixing and delivery time to 60 minutes. 4. When delivery time is in the excess of one hour, Architect may require dry-batch delivery. 5. "HOT" loads of concrete may be rejected by the Architect/Engineer. PART 3 EXECUTION 3.01 PREPARATION: A. Work Sequencing: Ensure that all reinforcing, inserts, anchors, and any other embedded items have been properly placed and securely anchored prior to placement of concrete. B- Cold Weather: Placement of concrete in cold weather is at Contractor's risk. Any defective concrete so caused shall be removed and replaced by the Contractor at his expense as directed by and to the satisfaction of the Architect. Sec Cast-in-Place Concrete page 6

13 C. Batch Plant Water: 1. Use water on Redi-Mix truck only for addition to mix design (The addition of any water to the mix is at the Contractor's risk). 2. Ensure water tank is full at time of delivery, with gauge at "Full" mark. When possible, position truck on level ground to allow accurate gauge readings. D. Protection: 1. Protect in-place concrete from adverse effects of weather or traffic during curing period. Do not place concrete during rain, sleet, snow or hail unless protection is provided. E. Pre-placement Work: 1. If required on drawings, install granular fill and/or sand and/or waterproofing membrane as specified elsewhere. 2. Install construction joints where required. Patch punctures in waterproofing membrane where penetrated prior to placing concrete. 3. Repair all punctures and/or penetrations in the waterproofing membrane. Make watertight and assure complete continuity of membrane. 4. Do not place any concrete without approval of Architect who requires 48 hours advance notice of intent to place. 5. Clean excavations thoroughly prior to placement of concrete. Hand- tamp bottom if required by Architect. Clean all reinforcing steel thoroughly prior to placing concrete. Remove and replace all damaged bar and fabric. 6. Tighten all form work. Remove and replace all damaged formwork. 7. Install anchor bolts and other embedded items using templates as required Secure in position as necessary to prevent displacement during placement of concrete PLACEMENT: A. General: Comply with ACI 304 and as specified herein. B. Maximum free drop of concrete shall not exceed 5 ft. for unexposed work; 3 ft. in exposed work. Use tremie or other approved means when greater drops are required. Space tremies to prevent segregation. Control discharge of tremie so concrete is effectively compacted into horizontal layers not more than 12 inches thick. C. Deposit concrete in forms in horizontal layers not deeper than 12 in. and in a manner to avoid inclined construction joints. D. Consolidate placed concrete by mechanical vibrating equipment supplemented by hand-spading, rodding or tamping. Use vibrators to operate with vibratory element submerged in concrete, maintaining a speed of not less than 6000 impulses per minute. E. Do not use vibrators to transport concrete inside of forms. Insert and withdraw vibrators vertically at uniformly spaced locations not farther than the visible effectiveness of the machine. Do not insert vibrators into lower layers of concrete that have begun to set. At each insertion, limit the duration of vibration to the time necessary to consolidate the concrete and complete Sec Cast-in-Place Concrete page 7

14 embedment of reinforcement and other embedded items without causing segregation of the mix F. When air temperature has fallen to or is expected to fall below 40 degrees F., uniformly heat all water before mixing as required to obtain a concrete mixture temperature of not less than 50 degrees F. and not more than 80 degrees F. at point of placement. G. When hot weather conditions exist that would seriously impair the quality and strength of concrete, place concrete in compliance with ACI 305 and as herein specified: 1. Cool ingredients before mixing to maintain concrete temperature at time of placement below 90 degrees F.. Mixing water may be chilled or chopped ice may be used to control the concrete temperature, provided the water equivalent of the ice is calculated to the total amount of mixing water. 2. Cover reinforcing steel with water-soaked burlap if it becomes too hot, so that the steel temperature will not exceed the ambient air temperature immediately before embedment in concrete. Wet forms thoroughly before placing concrete. 3. Do not use retarding admixtures without the written approval of the Architect FINISHES: A. General: Provide finishes specified in accordance with ACI 301. B. Slabs: 1. Interior: Troweled finish. Finish tolerance 1/8 inch in 10 ft. Slope to floor drains, 1/8 inch per foot typical All sloping slabs shall be a minimum of 4" thick, including the area around drains. 2. Exterior flat work, ramps, stairs, and elsewhere as shown on drawings: Broom finish. After initial steel troweling, finish with a stiff bristle broom drawn over the surface in parallel passes, transverse to flow of traffic. If necessary, spray lightly with water, immediately ahead of brooming. After brooming, finish edges and joints with a 1/4 inch radius edging tool, or as shown on drawings. 3. Recessed areas: Wood float finish at areas scheduled to receive a cement topping which will be subsequently finished. C. Exposed vertical surfaces: Rubbed finish to produce smooth, even surface free of blemish or stain. Rubbing to be performed with a wet carborundum stone and immediately after removal of forms. Cement wash not permitted CONCRETE CURING: A. Protect freshly placed concrete from premature drying and excessive cold or hot temperatures. Start initial curing as soon as free water has disappeared from concrete surface. B. Perform curing of concrete by moist curing, by moisture retaining cover curing, by membrane curing, or by combinations thereof. C. Provide moisture curing by keeping the concrete surface continuously wet with water spray, or by covering the concrete surface with absorptive cover. Thoroughly saturate the cover with water Sec Cast-in-Place Concrete page 8

15 and keep continuously wet CONCRETE SURFACE REPAIRS: A. Patching Defective Areas: 1. Repair and patch defective areas with cement mortar immediately after removal of forms, only after approval of Architect. 2. Cut out honeycomb, rock pockets, voids over 1/2 in. diameter and holes left by tie rods and bolts down to solid concrete, but in no case to a depth of less than 1 in. Make edges of cuts perpendicular to the concrete surface. Before placing cement mortar, thoroughly clean, dampen with water and brush-coat the area to be patched with neat cement grout. Proprietary patching compounds may be used when acceptable to Architect. B. Repair of Formed Surfaces: 1. Remove and replace concrete having defective surfaces if defects cannot be repaired to satisfaction of the Architect. Surface defects, as such, include color and texture irregularities, cracks, spalls, air bubbles, honeycomb, rock pockets and holes left by the tie rods and bolts; fins and other projections on surface; and stains and other discolorations that cannot be removed by cleaning. 2. Rub or grind rough areas and high spots to match plane of adjacent surface and to an acceptable smoothness unless otherwise directed by Architect. C. Repair of Unformed Surfaces: 1. Correct low areas in unformed surfaces during or immediately after completion of surface finishing operations by cutting out low areas and replacing with fresh concrete. Finish repaired areas to blend into adjacent concrete. Proprietary patching compounds may be used when acceptable to Architect. D. Grinding: 1. At all areas to be covered with a finish flooring which do not meet tolerances specified herein and greater than 3/16" in 10'-0", power grind to eliminate all protrusions. 2. Upon completion of surface grinding, fill all depressions remaining with Latex floor patch which is compatible with various floor mastics. 3. At exposed concrete areas which do not meet tolerances specified herein, the Architect at his discretion, may require grinding as indicated above depending on location and condition of s3-ilacl. Ohiir-vwisc and at his discretion, the Architect shall require the Contractor to remove and replace the concrete at the Contractor's own expense END OF SECTION Sec Cast-in-Place Concrete page 9