Would You Like Concrete With Little or No Shrinkage, Cracking, and Curling??? We Will Focus on: Coarse Aggregates Admixtures Including Shrinkage Reducing and Shrinkage Compensating Admixtures Evaporation Retarders and Curing Joint Layout and Saw Cutting Dave Flax Euclid Chemical Business Development Group Manager Southwest Region P: 858-405-0356 E:dflax@euclidchemical.com AIA The Construction Specifications Institute is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-aia members available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 1
CEN This program is a registered educational program with the Construction Specifications Institute of Alexandria, VA. The content within this program is not created or endorsed by CSI nor should the content be construed as an approval of any product, building method, or service. Information on the specific content can be addressed at the conclusion of this program, by the Registered Provider. Credit earned for completing this program will automatically be submitted to the CSI CEN. Completion certificates can be obtained by contacting the Provider directly. This logo and statement identify Provider programs registered with the CSI CEN and are limited to the educational program content. Dave Flax Civil Engineering Degree from RPI Over 30 years experience with concrete Years as a Field Engineer Years with a contractor Years with the Corps of Engineers doing research Published dozens of articles Specialized in cement and concrete 2
LETS TALK ABOUT SHRINKAGE Typical Concrete Shrinkage is about 0.06% But What Does That Mean? Shrinkage Shrinkage Probability (%) per 100 ft of Cracking 0.08 1 Almost certain 0.06 3/4 Very Probable 0.05 5/8 Likely per Corps of Engineers 0.04 1/2 Probably Not Many 0.02 1/4 Probably Very Few 0.0 0 Very Few, If Any Cracks (Also Joint Spacing Can be Expanded) 3
Typical Drying Shrinkage is.06% = 3/4 in 100 100 Without Restraint 99 11 1/4 4
But there is Restraint 100 From Subgrade Friction, Reinforcement, Etc. Shrinkage + Restraint = Cracks 99 11 7/8 1/8 1/8 1/8 1/8 1/8 5
WHY DOES CONCRETE SHRINK SO DARN MUCH? Cracks and Joints 6
Cracks and Joints Differential drying causes curling Cracks (joints) form in V shape 7
WATER 8
Pounds of Water EXCESS WATER IN ONE CUBIC YARD OF CONCRETE WITH 500 POUNDS OF CEMENT 400 350 300 250 200 150 100 50 0 1 2 EXTRA CUBIC FEET OF WATER.25.30.35.40.45.50.55.60.65.70.75 Water/Cement Ratio 3 4 500 lb cem.40 w/c 600 lb cem.40 w/c 9
And the reason that all this is so important is 10
COURSE AGGREGATES Coarse Aggregate Provide largest topsize coarse aggregate available that meets the following constraints. 1/5 of narrowest dimension between sides of forms. 1/3 of depth of slabs. 3/4 of minimum clear distance between reinforcing bars or between bars and forms, whichever is least. Minimum coarse aggregate of: 12 cubic feet for 1 ½ or larger topsize 11.5 cubic feet for topsize 1 ¼ or larger but less than 1 ½ 11 cubic feet for topsize 1 or larger but less than 1 ¼ 10.5 cubic feet for topsize less than 1. Combined aggregate gradation retained on each sieve below the top size and above the No. 100. 8% - 18% for large top size aggregates (1½ in.) or 8% - 22% for smaller top size aggregates (1 in. or ¾ in.) 11
Mix Design Comparison (Steel troweled interior floors subjected to vehicular traffic) -60-120 + 250-30 Add Same + 1 -$1 C O N V E N T IO N A L C O N C R E T E A T H L E T IC C O N C R E T E C e m e n t 635 lbs. 575 lbs. S a n d 1200 lbs. 1080 lbs. C oarse Aggregate 1850 lbs. (#467) 2100 lbs. (#467) W a te r 305 lbs. 275 lbs. Air C ontent (Entrapped) 1.5% 1.5% H R W R T y p e F @ 40 +/- oz. A d m ix tu r e 20+/-oz. Type A or as required W /C m 0.48 0.48 S lu m p 5 M axim um 2 3 Initial 5 7 F in a l a fte r addition of H R W R C o s t ----- $ - 1.00/c.y. (savings) 12
Newark International Airport Port Authority of NY & NJ - Newark Airport 13
95% less cracking as compared to their conventional concrete placed in the past SHRINKAGE REDUCING ADMIXTURES 14
Drying Shrinkage (Capillaries) Pore Water Evaporation 15
Capillary Pore Stress Stress = Cracks 16
Shrinkage Reducing Admixture (SRA) Reduce the surface tension of the meniscus So it doesn t pull in on the pore walls This reduces the internal tensile stresses And reduces the shrinking and cracking Shrinkage Reduction Cement Water Fine aggregate WR AEA SRA Example Coarse aggregate 517 lb/yd 3 255 lb/yd 3 1450 lb/yd 3 1700 lb/yd 3 3 oz/cwt 1.65 oz/cwt 2% by cementitious Length change (%) -0.005-0.01-0.015-0.02-0.025-0.03-0.035 Time (days) 0 0 7 14 21 28 35 42 49 56 Reference SRA 1 SRA 2 17
SHRINKAGE-COMPENSATING CONCRETE Shrinkage Reduction and Compensation days Length change Shrinkage Expansion 0 Shrinkage Compensation Time Shrinkage Reduction Portland Cement Concrete REINFORCEMENT in TENSION CONCRETE in COMPRESSION REINFORCEMENT in COMPRESSION CONCRETE in TENSION Based on figure from ACI 223R-10. The best results may be from using smaller amounts of Shrinkage Reduction and Shrinkage Compensation in combination. 18
ANOTHER WAY TO LOOK AT IT ORIGINAL LENGTH ORIGINAL LENGTH Potential Expansion 19
ORIGINAL LENGTH Potential Expansion REBAR, STEEL FIBER, or CABLE CONCRETE Actual Expansion ORIGINAL LENGTH Potential Expansion REBAR, STEEL FIBER, or CABLE CONCRETE Actual Expansion FINAL LENGTH 20
Reinforcement per ACI 223R-10 For a 6 slab this is equal to #3 @ 12 ocew or #4 @ 22 ocew Joints and Spacing per ACI223R-10 21
TYPICAL SLABS 210 by 240 50,400ft 2 TYPICAL SLABS 210 by 240 50,400ft 2 15 x 15 Portland Concrete 6270 lf of joints 22
TYPICAL SLABS 210 by 240 50,400ft 2 15 x 15 60 x 70 SAVED ALMOST A MILE OF JOINTS Portland Concrete 6270 lf of joints Shrinkage-Compensating 1110 lf of joints Less Curling per ACI 223R-10 23
An FF 50 is roughly equivalent to a single ± 1/8" defect in 10 feet An FF 100 is roughly equivalent to a single ± 1/16" defect in 10 feet Considered SUPERFLAT Readings for floor acceptance are normally taken within days. A floor will normally lose 30-40% of its flatness in the first year. 70,000 square feet Max Joint Spacing 130 No Cracks 1 day: FF = 99.2 5 weeks: FF = 98.6 1 year: FF = 97.8 24
Toppings per ACI 223R-10 Transfer Station Repair Most Properties Stay the Same per ACI 223R-10 Compressive Strength Flexural Strength Tensile Strength Modulus of Elasticity Freeze/Thaw Resistance Creep Coefficient of Thermal Expansion Sulfate Resistance (equal or better) Etc. 25
Abrasion Resistance Increased 30-40% per ACI 223R-10 Post-Tensioning per ACI 223R-10 When it was first developed decades ago, Shrinkage Compensating Concrete was called Self Post-Tensioning Concrete 26
Allow for Expansion per ACI 223R-10 REDUCED SHRINKAGE MIXES 27
0.04% Shrinkage Mix Per ASTM C 157 "Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete". 1. Use specified coarse aggregate quantity, size, and gradation. 2. Use High-Range or Mid-Range Water-Reducing Admixture. 3. Use Shrinkage Reducing or Shrinkage Compensating Admixture. (If necessary) 4. Admixture manufacturer shall assist with the development of the mix. 0.02% Shrinkage Mix Per ASTM C 157 "Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete". 1. Use specified coarse aggregate quantity, size, and gradation. 2. Use High-Range or Mid-Range Water-Reducing Admixture. 3. Use Shrinkage Reducing and/or Shrinkage Compensating Admixture. 4. Admixture manufacturer shall assist with the development of the mix. 28
0.0% Shrinkage Mix At 28 days per ASTM C 878 Standard Test Method for Restrained Expansion of Shrinkage Compensating Concrete. 1. Use specified coarse aggregate quantity, size, and gradation. 2. Use High-Range or Mid-Range Water-Reducing Admixture. 3. Use Shrinkage Compensating Admixture. (And possibly Shrinkage Reducing Admixture as well) 4. Admixture manufacturer shall assist with the development of the mix. Benefits of All Three Mixes Less cracking and curling The Engineer will need to decide which shrinkage is appropriate for their job. ASTM C878 29
EVAPORATION RETARDER AND CURING Evaporation Retarder and Curing Don t let the slab dry out!! For Shrinkage Reducing Admixtures and Standard Mixes: Evaporation retarder strongly suggested Curing compound may be used, but wet cure is preferable For Shrinkage-Compensating: Ties up more of the water Less bleed water Therefore: Evaporation retarder required Wet cure for 7 days required 30
WHEN WATER EVAPORATES OFF THE SURFACE TOO RAPIDLY, CRACKING USUALLY OCCURS. 31
THERE ARE FOUR FACTORS THAT CONTRIBUTE TO THIS: HIGH AMBIENT TEMPERATURES HIGH CONCRETE TEMPERATURES LOW HUMIDITY HIGH WINDS 32
Modest conditions: Air 70 o F Humidity 30 % Concrete 80 o F Wind 15 mph ACI 305.1 Nomograph Anything over 0.2 lbs/ft 2 /hr is unacceptable CURING 33
ACI 302.1R-96 (Section 9.1) Purpose of Curing: After concrete placement and finishing of suitable concrete, curing is the single most important factor in achieving a high quality slab. The primary purpose of curing is to slow the loss of moisture from the slab. A longer period of moisture retention permits more complete hydration of the cement, resulting in greater strengths. Curing Membranes are Most Common Easy to apply Cost effective Protect concrete during construction 34
Moisture Retaining Fabric Effect On Surface Strength Of Concrete Quality Curing Membrane 100% 80% 60% 40% 20% 0% Good Curing Poor Curing No Cure ALL CONCRETE MUST BE CURED 35
Dusting REMOVABLE CURE 36
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SUBGRADE 38
SUBGRADE Subgrade shall be properly compacted and shall have proper moisture content before slab placement. Typical spec language: A fully loaded ready mix truck shall not make a depression exceeding 1/2. JOINT LAYOUT 39
A few simple rules for Joint Layout: 1. Maximum joint spacing 2 ½ times thickness in feet (stated differently: 30 times the thickness) 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s Note that 1. and 2. can vary if shrinkage compensating admixture is used. A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 40
A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 15 5 A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 15 7.5 5 41
A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 15 10 15 15 20 A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 15 10 15 15 10 10 42
A few simple rules: 1. Maximum joint spacing 2 ½ times thickness in feet 2. Maximum length to width ratio 2 to 1 3. Joints at every re-entrant corner 4. No T s 15 15 6 thick slab 15 12.5 12.5 43
TESTING Freedom Tower NYC 44
Typical Spec Language: Water content testing: Field testing to verify the concrete water content and water/cement ratio shall be done by the microwave test method AASHTO T318, Standard Method of Test for Water Content of Freshly Mixed Concrete Using Microwave Oven Drying. TYPICAL APPLICATIONS 45
Do You See Some Places That a Normal Slab Would Almost Certainly Crack? Do You See Some Places That a Normal Slab Would Almost Certainly Crack? Etc, Etc, Etc 46
Warehouse Floor Soil Nailing Parking Garage Secondary Containment Water Treatment Bridge Roof Tank 47
Repair Topping Steel Deck Retail Loading Dock When it comes to construction its: The contractor s job to build it The specifier s job to tell them how in the spec My job to help with product selection and the spec 48
Any Questions? This concludes the credit portion of the program for The Construction Specifications Institute Construction Education Network and The American Institute of Architects Continuing Education System Dave Flax Euclid Chemical P: 858-405-0356 E:dflax@euclidchemical.com 49