Sustainable Concrete for the Illinois Tollway Matthew D Ambrosia, Ph.D, P.E. August 20, 2013
Sustainable Concrete Must Meet Multiple Objectives Mechanical Properties Compressive Strength Tensile Strength Flexural Strength Elastic Modulus Fracture Toughness Sustainability Cracking Corrosion ASR DEF F-T Durability Constructability Workability Flowability Slump Loss Finishability Setting
The Role of Specifications Prescriptive specifications limit innovation, drive the contractor and supplier to focus primarily on strength Performance specifications allow new materials, new design approaches, and focus on durability Can be a less expensive solution for the owner Approach considers mechanical properties, durability, and constructability
Sustainable Concrete Starts With Portland Cement Every year, about a cubic yard of concrete is made for every person on the planet Domestic cement production responsible for about 1.0% of U.S. total CO 2 (3.5% globally) Portland cement is about 90% to 95% of CO 2 and 85% of embodied energy in concrete
The Cement Industry... Has increased the efficiency of their clinkering process, reducing the CO 2 to cement clinker ratio (clinker factor) Offers a plethora of blended (ASTM C595) and performance specified (ASTM C1157) cements Is developing new cements that may further reduce the CO 2 and energy footprint
Yet Roughly 0.57 tons of CO 2 is liberated per ton of portland cement produced due to calcination of limestone (CaCO 3 ) Heat CaCO 3 CaO + CO 2 Can reduce the energy needed to some degree, but can t change the chemistry Or can we????? CaCO 3 CaO + C + 2O
What About Concrete? The solution is to reduce the amount of portland cement in concrete Reduce cement content (e.g. 564 to 470 lbs/yd 3 ) Increased use of SCMs such as fly ash, slag, natural pozzolans, and others Reduce amount of concrete used Cement strength or durability use w/c
Cement Content and CO 2 Pounds CO 2 /yd 3
Points to Emphasize Portland cement is the major source of CO 2 and embodied energy in concrete, so reduce content Good mixture proportioning can reduce cementitious content Use blended cements and SCMs Create long-lasting, durable structures
Durability of FRAP and B-quality Aggregate in Pavements Matthew D Ambrosia, Ph.D., P.E. August 20, 2013
Black Rock in Concrete Coarse portion of fractionated RAP ½ to #4 Austria standard practice in lower lift US Trial: Florida 1 st Tollway Trial: Milwaukee Avenue ramp 2010
Questions for Durability Fines, organics, effect of washing Asphalt agglomerations, strength Freeze-thaw
FRAP and B-Quality Ternary Mixtures ASTM C192 Mixture Summary B1 B2 Frap A Frap B Frap C Material lb/yd 3 (SSD) Cement 370 370 370 370 370 Fly Ash 15% 85 85 85 85 85 Slag 20% Quality 115 115 115 115 115 Coarse Aggregate B- 1880 1916 647 637 640 Coarse Aggregate A- 0 0 1240 1240 1240 Fine Aggregate 1190 1190 1190 1190 1190 Water 238 238 228 228 228 w/cm 0.42 0.42 0.40 0.40 0.40 fl. oz./cwt (100 lbs of cementitous material) Air Entraining Agent 1.41 1.02 1.02 1.02 1.02 Water Reducer 4.00 4.00 4.00 4.00 4.00 Measured Fresh Properties Slump, in. 0.75 2.25 1.5 2.5 2.25 Air Content, % 6.5% 8.0% 7.0% 8.5% 8.0% Temperature, F 72.8 71.2 72.3 73.7 73.8 Fresh Density, lb/ft 3 145.0 143.6 144.3 141.3 142.8 20% FRAP
Fines and organics in solution
B-Quality compressive strength is adequate 7,000 B1 B2 Frap A Frap B Frap C Compressive Strength, psi 6,000 5,000 4,000 3,000 2,000 1,000 0 7 14 28 Concrete Age, days
Freeze-thaw performance with FRAP and B-quality aggregates was satisfactory 120 100 Arrow A Arrow B Arrow C Arrow Average Bluff A Bluff B Bluff C Bluff Average Vulcan A Vulcan B Vulcan C Vulcan Average K-5 A K-5 B K-5 C K5 Average Allied A Allied B Allied C Allied Average Relative Dynamic Modulus (RDM), % 80 60 40 20 0 0 50 100 150 200 250 300 350 No. of Cycles
Failure in one B-quality aggregate due to one or two particles
High-Performance Concrete for Bridge Decks Matthew D Ambrosia, Ph.D, P.E. August 20, 2013
The approach C 3 Enhance sustainability Develop a spec that produces constructible HPC Reduce or minimize cracking of the deck Improve the resistance to chloride penetration Provide adequate freeze-thaw resistance All other properties should be unharmed
Candidate Bridge Deck HPC Mixtures BS: Standard Bridge Deck Mixture OPT: Optimization of Aggregate Gradation SLA: Saturated Lightweight Aggregate SRA: Shrinkage Reducing Admixture ULT: Combined approach (OPT + SRA + SLA)
Target Mixtures Reduce cementitious%, increase SCM% Mix ID: BS OPT SLA SRA ULT Material lb/yd 3 (SSD) Cement 515 375 409 403 313 Fly Ash 0 125 0 134 111 Slag 110 0 136 0 154 Coarse Aggregate (CM-11) 1875 1501 1714 1840 1245 Coarse Aggregate (CM-16) 0 391 0 0 325 Saturated Lightweight Fines 0 0 364 0 236 Fine Aggregate 1160 1370 986 1323 1039 Water 263 210 237 226 220 Total Cementitious Content 625 500 545 536 578 w/cm (including water in admixtures) 0.43 0.43 0.44 0.43 0.39
Slump Retention = Constructability 12 10 8 BS OPT SLA SRA ULT Slump, in 6 4 2 0 0 10 20 30 40 50 60 Elapsed time, min
Air loss monitored during trials 10% Air Content, % 9% 8% 7% 6% 5% 4% 3% 2% 0 10 20 30 40 50 60 70 80 90 Elapsed time, min BS OPT SLA SRA ULT Hardened Air
Compressive strength gain enhanced by SCMs Average Compressive Strength, psi 10,000 8,000 6,000 4,000 2,000 BS OPT SLA SRA ULT [min] [min] [min] [min] [min] initial set: 300 458 350 537 514 final set: 374 543 426 638 642 BS OPT SLA SRA ULT 0 0 7 14 21 28 Concrete Age, days
Chloride penetration resistance (28d accelerated) 1250 Rapid Chloride Penetrability, coulombs 1000 750 500 250 0 BS OPT SLA SRA ULT
NEED: Measurement of cracking tendency ASTM C1581 Concrete shrinks around the steel ring causing tensile stress in concrete Stress relaxes due to tensile creep Strain measurements in steel are proportional to stress in concrete When tensile stress exceeds strength, cracking occurs
ASTM C1581 Interpretation Requirement for patches: 10 days Requirement for new decks: 28 days
Comparison of Ring Test Results 20 Average Time to Cracking 15 Time, days 10 5 0 PP-2 Patch 100 525-20 600-10-A
Role of Fibers in Restrained Shrinkage Fibers did not have much impact on cracking time Fibers reduced crack widths by 5x
Crack resistance is improved Strain x10-6 20 0-20 -40-60 BS OPT SLA SRA ULT SLA - One Ring Cracked SRA - None Cracked OPT - One Ring Cracked -80-100 BS - Three Rings Cracked @ 12-16 days 0 10 20 30 40 50 60 Time, days ULT - None Cracked
Elastic modulus or brittleness is reduced 6,250 28 day Elastic Modulus, ksi 6,000 5,750 5,500 5,250 5,000 BS OPT SLA SRA ULT
Linear Drying Shrinkage 0.01 Length Change, % 0.00-0.01-0.02-0.03 BS-F2 OPT-F2 SLA-F2 SRA-F2 ULT-F2-0.04-0.05 0 20 40 60 80 Age, days
Freeze-thaw 300+ cycles with no damage 110 100 RDM, % 90 80 70 BS OPT SLA SRA ULT 60 50 0 100 200 300 400 500 No. of Cycles
UIUC - Uniaxial Creep-Shrinkage Test
HPC stress development is mitigated 450 Restrained Tensile Stress Development, psi 400 350 300 250 200 150 100 50 * BS SRA OPT ULT SLA-F4 * 0 0 2 4 6 8 10 12 Concrete Age, days *w/cm significantly lower than original design, generating more early shrinkage than anticipated
Test Method Performance Requirement Time, days AASHTO T 22-10 4000 f cr [f cr + 1500] psi at 14 days 14 AASHTO T 119 ASTM C1581-09a AASHTO T 160-09 AASHTO T 161(A)-08 Slump greater than 3" for 45 minutes after water added to cement Minimum 28 days with no cracking Exempt when less than 600 lb/yd 3 cementitious and a minimum of 1.5 gal/yd 3 SRA is used? Maximum 0.03 percent after 7 days curing and 21 days drying, zeroed at the start of drying Minimum RDM of 80 percent after 300 cycles Exempt if ASTM C457 requirements are met and aggregate is IDOT Class A+ 1 28 (0) 28 74 (7) AASHTO T 303 Expansion less than 0.10% at 16 days Exempt if total alkali content from cement is less than 4 lb/yd 3 16 (7) ASTM C457-11 Spacing factor not exceeding 0.008-in Specific surface not less than 600 in 2 /in 3 Total air content not less than 4.0% 7 AASHTO T 277-07 Max 1250 coulombs after 28 day accelerated curing 30
Qualification Process Materials Concrete Supplier Design Proportions Optional Preliminary Testing Testing ok? No Yes Lab Lab Testing Requirements: Slump Loss Fresh Air Content Compressive Strength (determine f cr) Restrained Shrinkage Drying Shrinkage Rapid Chloride Penetrability Freeze-Thaw Durability Alkali Silica Reactivity Hardened Air-Void Analysis Petrographic Analysis Chemical Analysis Lab Qualification Testing ok? Yes No Revise and resubmit Trial Batch Testing Requirements: (performed at batch plant) Slump Loss Fresh Air Content Hardened Air-Void Analysis (optional) Compressive Strength Rapid Chloride Penetrability Trial Batch Testing ok? No Yes Tollway Approved Mixture Design Bid Documents: QMP Approved Mixture Proportions Materials Sources Contractor Field Acceptance Testing Requirements: (performed at project site) Slump Fresh Air Content Compressive Strength Rapid Chloride Penetrability Hardened Air-Void Analysis (optional) Petrographic Analysis (optional) Chemical Analysis (optional) Field Acceptance Testing ok? No Yes Tollway Acceptance
Preliminary Steps Materials Selection Materials Concrete Supplier Design Proportions Optional Testing Design Proportions Submit to Lab Optional Preliminary Testing Testing ok? No Yes Lab
Mixture Qualification Lab Testing Requirements: Slump Loss Fresh Air Content Compressive Strength (determine f cr ) Restrained Shrinkage Drying Shrinkage Rapid Chloride Penetrability Freeze-Thaw Durability Alkali Silica Reactivity Hardened Air-Void Analysis Petrographic and Chemical Analysis Trial Batch Testing Requirements: (performed at batch plant) Slump Loss Fresh Air Content Hardened Air-Void Analysis (optional) Compressive Strength Rapid Chloride Penetrability Lab Qualification Testing ok? Yes Trial Batch Testing ok? Yes Tollway Approved Mixture Design No No Revise and resubmit
Implementation Bid Documents: QMP Approved Mixture Proportions Materials Sources Field Acceptance Testing Requirements: (performed at project site) Slump Fresh Air Content Compressive Strength Rapid Chloride Penetrability Hardened Air-Void Analysis (optional) Petrographic Analysis (optional) Chemical Analysis (optional) Contractor Field Acceptance Testing ok? Yes No Tollway Acceptance
Acknowledgements Steve Gillen and Ross Bentsen, Illinois Tollway Professor David Lange and William Wilson, UIUC Jay Behnke, Greg Rohlf, Derek White, STATE Testing Bill Vavrick, Applied Research Associates (ARA) Local Contractors and Concrete Producers
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