Presentation on theme: "Mark B. Snyder, Ph.D., P.E., Engineering Consultant Bridgeville, Pennsylvania Prepared for presentation at the 2008 Minnesota Concrete Conference Continuing."— Presentation transcript:
Mark B. Snyder, Ph.D., P.E., Engineering Consultant Bridgeville, Pennsylvania Prepared for presentation at the 2008 Minnesota Concrete Conference Continuing Education and Conference Center, St. Paul, MN February 14, 2008
FHWA-Sponsored Research University of Minnesota ERES Consultants, Inc. Physical and Mechanical Properties of Recycled PCC Aggregate Concrete 1993 - 1999 of Recycled PCC Aggregate Concrete 1993 - 1999
RCA has been used widely with varying results. Most common failures: deteriorated midpanel cracks loss of load transfer
Determine causes of pavement distress related to use of RCA in PCC pavements. Develop practical, reliable guidelines for RCA concrete mix designs. Identify pavement designs for which RCA concrete is appropriate.
Extensive Literature Review Field Testing and Evaluation Laboratory Testing and Evaluation
l Distress (cracked, uncracked, other) l JRCP, JPCP (CRCP?) l Available control section l Range of climates, traffic l Uniform traffic flow l No substructures
Original 1993 Study: 9 Projects 5 RCA + Control4 RCA Only 2 Single Sections 1 Varying LT 1 Varying Performance 16 Sections Total
CategoryLocationClimatic Region 1994 Age, Yrs Control Section 2 Way ADT, veh/day Pavement Type (% long. reinf.) Joint Spacing, ft Dowel Diam., in 1 (Good) CT 1, I-84 near Hartford W-F14yes56,0009-in JRCP (0.10 %) 401.5 (I-beam) MN 1, I-94 near Brandon W-F Transition 6yes8,17011-in JRCP (0.06 %) 271.25 KS 1, K-7 Johnson County W-F9yes7,3109-in JPCP (n/a) 15None 2 (Structural Problems) MN 4, US52 near Zumbrota W-F10yes7,8209-in JRCP (0.06 %) 271.0 MN 2, I-90 Beaver Creek W-F Transition 10no1,6709-in JRCP (0.06 %) 271.0 WI 1, I-94 near Menomonie W-F10no8,17011-in JPCP (n/a) 12-13-19-18None / 1.375 3 (Other Distresses) MN 3, US59 near Worthington W-F Transition 14no2,1508-in JPCP (n/a) 13-16-14-19None WI 2, I-90 near Beloit W-F8no22,62210-in CRCP (0.67 %) n/a WY 1, I-80 near Pine Bluffs D-F9 / 10yes4,410 (RCA) 4,280 (Con.) 10-in JPCP (n/a) 14-16-13-12None
Compression Split Tension Static E Dynamic E Surface Texture Sand Patch Profilometer Freeze-Thaw Linear Traverse Petrography
FHWA-Sponsored Research University of New Hampshire Recycled Materials Resource Center Performance of Concrete Pavements Containing Recycled Concrete Aggregate 2006 (Update of previous study)
Revisit 1994 study sections to obtain longer-term materials and performance data. Include additional test sites to expand inference base of original study. Update conclusions from 1994 study.
CategoryLocationClimatic Region 2006 Age, Yrs Control Section 2 Way ADT, veh/day Pavement Type (% long. reinf.) Joint Spacing, ft Dowel Diam., in 3 (Other Distresses) IA 1, US 75 near Rock Rapids W-F30no2,1509-in JPCP (n/a) 13-16-14-19None IL 1, I-57 near Effingham W-F20no4,410 (RCA) 4,280 (Con.) 10-in CRCP (n/a) n/a
Test and Value MN 1-1 (Recycled) MN 1-2 (Control) Transverse Joint Spalling, % Joints 7654 Avg. Faulting between Panels, mm0.91.3 Longitudinal Cracking, m/km00 Transverse Cracking, % Slabs310 Deteriorated Transverse Cracks/km 350 Total Transverse Cracks/km380 PSR3.74.0 IRI1.10.9 Tensile Strength, MPa2.93.3 Compressive Strength, MPa44.959.0 Uranyal Acetate ReactionNone Youngs Modulus, GPa28.933.4
Comparable performances in 1994 Mortar Content 77% RCA 66% Control Similar Thermal Coefficients in 1994 11.9/C o RCA 11.9/C o Control ~25% increase in Youngs modulus since 1994 Inconsistent strength trends since 1994 RCA strength consistently lower, but adequate
Project Review and Performance Summary (Age 22 yrs)
MN 3-1 (Recycled) Sturtevant M.S. Thesis - 2007
Test and Value MN 3 (1994) MN 3 (2006) Transverse Joint Spalling, % Joints 7189 Transverse Joint Seal Damage, % Joints 760 D-cracking, % Slabs00 Avg. Faulting between Panels, mm6.10.3 Avg. Joint Width, mm2018 Longitudinal Cracking, m/km190 Transverse Cracking, % Slabs212 Deteriorated Transverse Cracks/km 326 Total Transverse Cracks/km326 PSR3.04.3 IRI1.70.6 Tensile Strength, MPa4.13.7 Compressive Strength, MPa44.152.4
42 Recycled section only Constructed in 1980 Rehabilitated after 1994 Diamond grinding Retrofitting of transverse dowel bars PSR = 4.3 (3.0 in 1994) Avg. faulting between panels = 0.3 mm (6.1 mm in 1994) No recurring D-cracking ASR found during uranyl acetate testing Moderate expansion in Modified ASTM 1293 testing No ASR related distress found in field
Project Summary and Performance Review (Age – 22 yrs)
In 1994, performances were comparable, but RCA section was showing signs of imminent deterioration Foundation Stiffness (backcalculated) 30% lower for RCA section Aggregate Top Size 1.0-in RCA 1.5-in Control Mortar Content 84% RCA (higher shrinkage?) 52% Control Similar Thermal Coefficients in 1994 12.4/C o RCA 11.9/C o Control ~10% increase in compressive strength since 1994
47 Recycled and control sections rehabilitated after 1994 Diamond grinding Retrofitting of transverse dowel bars Field survey showed recycled did not perform as well as control Recycled had higher mortar content (74% vs. 52%) Formation of shrinkage cracks early on
Need to treat RCA as engineered material and modify mix and structural designs accordingly Reduce w/c ASR mitigation Reduced panel lengths Etc. Mortar contents generally higher for RCA Reclaimed mortar content varied with virgin aggregate type, crushing process RCA, conventional aggregate PCC performance comparable when natural CA types and quantities are similar Higher mortar contents had more distress – need to control reclaimed mortar content
Use of RCA has no apparent direct influence on joint faulting (dowels, aggregate size, structural design parameters are more important) Recycled ASR concrete used successfully in Wyoming with mitigation measures Isolated recurrent ASR RCA performed better than control Recycled D-cracked concrete used successfully with mitigation measures Reduced aggregate size Reduced moisture exposure?
Federal Highway Administration Minnesota Department of Transportation Jeff Sturtevant, Prof. David Gress and the University of New Hampshire Recycled Materials Resource Center (RMRC) Greg Cuttell, Julie Vandenbossche and many other former U-M Grad and Undergrad Research Assistants Applied Research Associates, Inc. (formerly ERES Consultants)
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