[2008]     NEW T -B ECHNOLOGY ASED A A H PPROACH TO DVANCE IGHER V F A C OLUME LY SH ONCRETE WITH A P CCEPTABLE ERFORMANCE New Technology-Based Approach to Advance Higher Volume Fly Ash Concrete With Acceptable Performance FINAL REPORT (2008) Start Date: July 1, 2006 End Date: June 30, 2008 (DOE funding cut on March 30, 2007) Authors: Karthikeyan H. Obla, Sushant Upadhyaya, Dimitrios Goulias, Anton K. Schindler, and Nicholas J. Carino Report Issue Date: August 2008 Subcontract No. 98-166-NRMCA DOE Award Number 05-CBRC-M20 RMC Research & Education Foundation Project No. 07-09 Committee: Contractor: Karthikeyan H. Obla and Colin L. Lobo National Ready Mixed Concrete Association 900 Spring Street, Silver Spring, MD 20910 Sub Contractors: Dr. Dimitrios Goulias University of Maryland Department of Civil and Environmental Engineering, College Park, MD 20742 Dr. Nicholas J. Carino, Concrete Materials Consultant National Institute of Standards and Technology (retired) Gaithersburg, MD 20886 Dr. Anton Schindler Auburn University Department of Civil Engineering, Auburn, AL 36849 Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. 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All rights reserved. © 2008 National Ready Mixed Concrete Association. Abstract The use of fly ash in concrete has received significant attention over recent years due to environmental concerns regarding its disposal and potential for use as a cementitious material with its ability to provide significant benefits to concrete. While fly ash content less than 25% of total cementitious content is routinely used in concrete, high-volume fly ash (HVFA) concrete is not common due to perceived lower early-age strengths. The objective of this study was to demonstrate using maturity based techniques that the beneficial effects of high in-place temperature may be able to compensate for the slower rate of strength gain in HVFA concrete that is typically observed when tested under standard laboratory temperature conditions. In addition, different methods (match-cured cylinders, pullout testing) were used to estimate the early-age in-place strength of HVFA concrete to confirm the maturity predicted strengths. The results have shown that the standard and field-cured cylinder strengths underestimate the in-place concrete strength. Higher in-place temperatures due to the mass characteristics of structural elements resulted in increased early age in-place strengths, adequate for construction scheduling, as measured by match-cured cylinders, pullout testing, and the maturity approach. Keywords: Concrete, Fly Ash, Supplementary Cementitious Materials, Maturity, Pullout Test. Table of Contents Executive Summary ............................................................................................................ 1  Chapter 1  – Introduction ................................................................................................ 2  Chapter 2  – Background ................................................................................................ 5  2.1 Maturity Method ....................................................................................................... 5  2.2 Pullout Test ............................................................................................................... 7  2.3 Match Curing ............................................................................................................ 7  2.4 Push out Cylinders .................................................................................................... 7  Chapter 3  – Experimental Work – Mortar ..................................................................... 9  3.1 Materials ................................................................................................................... 9  3.2 Mixing Mortar ......................................................................................................... 11  3.3 Mortar Testing ........................................................................................................ 11  3.3.1 Fresh Mortar Tests ............................................................................................... 11  3.4 Mixture Proportions ................................................................................................ 12  3.5 Discussion of Test Results ...................................................................................... 15  3.5.1 Fresh Mortar Properties ....................................................................................... 15  3.5.2. Compressive Strength ......................................................................................... 18  3.5.3. Calculation of Activation Energy ....................................................................... 20  Chapter 4  – Experimental Work – Concrete ............................................................... 27  4.1 Materials ................................................................................................................. 27  4.2 Mixing Concrete ..................................................................................................... 27  4.3 Concrete Testing ..................................................................................................... 27  4.3.2 Hardened Concrete Tests ..................................................................................... 27  4.4 Mixture Proportions ................................................................................................ 34  4.5 Discussion of Test Results ...................................................................................... 35  4.5.1 Fresh Concrete Properties ................................................................................... 35  4.5.2 Standard-Cured Strength Results and Strength-Maturity Relationship ............... 35  4.5.3 Pullout Force Test Results and Pullout Force Versus Strength Correlation ........ 39  4.5.4 In-Place Strength Estimates Based on Field-Cured and Match-Cured Cylinder Strengths ....................................................................................................................... 42  4.5.5 In-Place Strength Estimates Based on Pullout and Maturity ............................... 45  Chapter 5  – Semi-Adiabatic Calorimetry Testing ....................................................... 51  5.1 Quantifying the Total Heat of Hydration of the Cementitious Materials ............... 51 5.2 Quantifying the Degree of Hydration Development ............................................... 52  5.3 Temperature Sensitivity of Cementitious Materials ............................................... 53  5.4 Modeling the Heat Generation and Temperature Associated with Hydration ........ 53  5.5 Experimental Work ................................................................................................. 54  5.6 Test Data and Discussion of Results ....................................................................... 55  Chapter 6  – Conclusions .............................................................................................. 59  References ......................................................................................................................... 60  Appendix A ....................................................................................................................... 64  Appendix B ....................................................................................................................... 72  Appendix C ....................................................................................................................... 83  Appendix D ....................................................................................................................... 85  Appendix E ....................................................................................................................... 89 List of Figures Figure 2.1 Pullout setup (Carino 2004)............................................................................... 7  Figure 3.1 Temperature sensor (iButton®) ....................................................................... 12  Figure 3.2 Setting times of mortar mixtures ..................................................................... 16  Figure 3.3 Compressive strength vs. actual age (35% FA-A mixture) ............................. 19  Figure 3.4 Compressive strength vs. actual age (35% FA-C mixture) ............................. 20  Figure 3.5 Rate constant vs. temperature-control mixture (AE-41400l J /mol) ............... 22  Figure 3.6 Rate constant vs. temperature-20% FA-A (AE-48100 J /mol) ........................ 22  Figure 3.7 Rate constant vs. temperature-35% FA-A (AE-l5600 J /mol) ........................ 23  Figure 3.8 Rate constant vs. temperature-50% FA-A (AE-33400 J /mol) ........................ 23  Figure 3.9 Rate constant vs. temperature-35% FA-B (AE-33000 J /mol) ........................ 24  Figure 3.10 Rate constant vs. temperature-35% FA-C (AE-28300l J /mol) ..................... 24  Figure 3.11 Arrhenius plots for the various mixtures ....................................................... 26  Figure 4.1 Match cure system showing 8 match-cured cylinder molds connected to a micro-controller computer ................................................................................................ 28  Figure 4.2 Custom 8 × 8 × 8-in. cube mold ...................................................................... 29  Figure 4.3 Cube molds with pullout inserts at the centers of the 4 side faces .................. 30  Figure 4.4 Pullout equipment ............................................................................................ 30  Figure 4.5 Field block with pullout inserts and temperature sensors ............................... 31  Figure 4.6 Concrete block curing in field. ........................................................................ 32  Figure 4.7 Concrete slab with cast-in-place cylinders and temperature sensors .............. 33  Figure 4.8 Slabs with cast-in-place cylinders, floating inserts and field cure cylinders (The red marking are the pullout inserts, field-cured cylinders are placed outside the slab and the cast-in-place cylinders are within the slab) .......................................................... 34  Figure 4.9 Maturity model- control mixture ..................................................................... 37  Figure 4.10 Maturity model- 35% FA-A mixture ............................................................. 37  Figure 4.11 Maturity model- 50% FA-A mixture ............................................................. 38  Figure 4.12 Maturity model- 35% FA-C mixture ............................................................. 38  Figure 4.13 Compressive strength vs. pullout force relationship-control mixture ........... 40  Figure 4.14 Compressive strength vs. pullout force relationship-35% FA-A mixture ..... 41 Figure 4.15 Compressive strength vs. pullout force relationship-50% FA-A mixture ..... 41  Figure 4.16 Compressive strength vs. pullout force relationship-35% FA-C mixture ..... 42  Figure 4.17 Compressive strength vs. age for different curing conditions (Control mixture-block) ................................................................................................................... 43  Figure 4.18 Compressive strength vs. age for different curing conditions (Control mixture-slab) ..................................................................................................................... 43  Figure 4.19 Compressive strength vs. age for different curing conditions (35% FA-A mixture-block) ................................................................................................................... 44  Figure 4.20 Compressive strength vs. age for different curing conditions (35% FA-C mixture-block) ................................................................................................................... 44  Figure 4.21 Compressive strength vs. age for different curing conditions (50% FA-A mixture-slab and block) .................................................................................................... 45  Figure 4.22 Comparison of strength obtained from various methods vs. equivalent age (Control-mixture block) .................................................................................................... 48  Figure 4.23 Comparison of strength obtained from various methods vs. equivalent age (50% FA-A-block) ............................................................................................................ 48  Figure 4.24 Comparison of strength obtained from various methods vs. equivalent age (35% FA-A block) ............................................................................................................ 49  Figure 4.25 Comparison of strength obtained from various methods vs. equivalent age (35% FA-C block)............................................................................................................. 49  Figure 4.26 Comparison of strength obtained from various methods vs. equivalent age (Control mixture-slab) ...................................................................................................... 50  Figure 4.27 Comparison of strength obtained from various methods vs. equivalent age (50% FA-A-slab) .............................................................................................................. 50  Figure 5.1 Effect of change in fly ash A proportions and w/cm on cumulative heat of hydration development ...................................................................................................... 56  Figure 5.2 Effect of change in fly ash A proportions and w/cm on rate of hydration ...... 57  Figure 5.3 Effect of change in fly ash type and w/cm on cumulative heat of hydration development ...................................................................................................................... 58  Figure 5.4 Effect of change in fly ash type and w/cm on rate of hydration ...................... 58  Figure A.1 Specimens for task 3 ....................................................................................... 68