ENGINEERING RESEARCH INSTITUTE THE UNIVERSITY OF MICHIGAN ANN ARBOR Progress Report THE EFFECT OF VARIATIONS IN AMOUNT OF WATER ADDED TO FLY-ASH CONCRETE MIXES Fo Eo Legg, Jro Assistant Professor of Engineering Materials and Assistant Supervisor, Michigan State Highway Department Laboratory Ralph Ho Vogler Research Assistant Project 2211 THE DETROIT EDISON COMPANY DETROIT, MICHIGAN September 1956

The University of Michigan * Engineering Research Institute SYNOPSIS In previous investigations of the use of Detroit Edison Company fly ashes in portland-cement concrete it appeared possible that an increase in the mixing water, while producing a more fluid mix, did not produce a commensurate reduction in the compressive strength of the concrete. As a result, a study was made in which concrete mixes designed for a 4-inch slump were made with the water added at the mixer increased or decreased from the designed quantity to produce wet and dry consistency mixes. The base mixes were so selected that the concrete of a given consistency had approximately the same early compressive strength whether containing fly ash or not. The results obtained indicate that there is no appreciable difference between the behavior of the mixes containing fly ash and the plain-cement mixes with respect to added water. The addition of extra water to produce the wetter mixes was equally detrimental to the compressive strength of both the fly-ash and plain-cement concrete. OBJECTIVE The purpose of this investigation is to study the properties of fly ash and concrete containing fly ash. The specific object of the research is to determine the effect of fly ash in concrete, as indicated by compressive strength, workability, durability in freezing and thawing, flexural strength, and other measures of concrete quality. ii

The University of Michigan ~ Engineering Research Institute INTRODUCTION This progress report is one of a series on the use of fly ash from The Detroit Edison Company power stations in portland-cement concrete. Presented herein are the results of a study to determine the effect of variations in the amount of water added to mixes of non-air-entrained concrete containing fly ash from the St. Clair stationo The investigation was made by the Engineering Research Institute of The University of Michigan pursuant to a contract between the Institute and The Detroit Edison Companyo This report covers only such matters as mix design, tests on the fresh concrete, and compressive strength through 90 days' age. Cylinders for testing at an age of one year were made and will be tested at the proper time. Some matter pertaining to test procedures which was covered in earlier reports will be omitted here to avoid repetition.. This investigation was intended to be in the nature of a pilot study, making a minimum number of mixes, and the scope can be extended if the results warrant such action. The method employed in this study consisted of making concrete of three consistencies from each of three mix designs by varying the amount of water added at the mixer. This gives the effect of a mix in which part of the water is omitted, making a drier mix, and one in which extra water is accidentally or intentionally added to give a wetter consistency. These can then be compared with the batch made of average consistency. The case with too much water is the more prevalent, particularly in transit-mix operations, where some of the wash water may not be discharged prior to charging the mixer with a new batch, or where the purchaser may direct the driver to add more water to make the concrete more fluid for easy filling of the forms. ~.~~~ I 1

The University of Michigan ~ Engineering Research Institute MIX DESIGN The "Recommended Practice for Selecting Proportions for Concrete" (ACI 613-54), the standard of the American Concrete Institute, was used as the design basis for all the mixes, with a slight modification for the mixes containing fly asho Increased coarse-aggregate contents over those recommended by the ACI were again used in the fly-ash mixes in the amounts found to be satisfactory in previous studies using the same materials. Three mixes were investigated, namely, 5.5 sacks of cement with no fly ash and 4.5 sacks of cement with, respectively, 100 and 200 pounds of fly ash per cubic yard of concrete. The cement and fly-ash contents were selected to yield approximately equal strengths between mixes for a given slump in the range most normally employed in construction. All mixes were designed originally for a slump of about four inches. MATERIALS The concrete materials were the same as those used and reported previously. The coarse aggregate was one-inch-maximum-size natural gravel, the fine aggregate was a natural sand having a fineness modulus of 3.0, the cement consisted of a blend of equal amounts of Huron, Peninsular, and Peerless brands, and the fly ash was from the St. Clair station. Results of tests on all of these materials have been reported previously, the fly ash in report Noo 2211-8-P and the cement in report No. 2211-10-P. FABRICATION OF SPECIMENS AND TEST PROCEDURES The methods of mixing, fabricating, curing, and testing were generally the same as used previously. The principal variation was in the addition of water at the mixer. Three consecutive batches were made from the same design, using the same weights of sand, gravel, cement, and fly ash. In the first batch only enough water was added to give a slump of about one inch. In the second batch, water was added to give a slump of about four inches. The third batch was made quite wet, with water being added until a slump of about eight inches was obtained. Special care was taken with the third batch to minimize segregation while molding the cylinders. ~- 2

The University of Michigan ~ Engineering Research Institute The sand was used in the moist condition in all but the last few batches of concrete made in this study. The moisture content was determined in advance of making the mixes and the batch weights were adjusted to compensate for the contained moisture. Ten cylinders were made from each batch, and there were two repeat mixes for each cement and fly-ash combination, providing six cylinders for each age of 1, 7, 28, 90, and 365 days. These cylinders were moist cured until time for testing. DISCUSSION OF TEST RESTULTS A detailed tabulation of mix proportions, results of tests on fresh concrete, and compressive strengths of test cylinders is presented in Tables I-A, II-A, and III-A in the Appendix. Summaries of important aspects of these results will be presented in the body of the report. 1. CEMENT CONTENT The mixes were designed to contain 5.5 sacks of cement per cubic yard in the concrete with no fly ash and 4.5 sacks in concrete containing fly ash. Increasing or decreasing the water from the design quantity without making compensating changes in the quantities of the other materials results in over- or under-yield and the actual cement content will be too low or too high. The quantities of sand, gravel, and water reported are based on the nominal yield, no adjustment being made for the over- or under-yield. 2. COMPRESSIVE STRENGTH Average values of compressive strength are given in Table I. For a given slump, differences in the strength of the three mixes are not large at ages up to 28 days. At 90 days there is somewhat greater variation, particularly in the mixes of medium consistency. At the later age, the mixes with fly ash have higher strengths than the comparable mixes without fly ash but containing more cement. At the outset of this study it was conjectured that the fly-ash mixes would not vary in compressive strength with a variation in water as much as the mixes without fly ash. Comparison can be made by determining the loss of compressive strengths between the dry and wet consistency mixes for each of the cement and fly-ash contents. These values are shown in Table II. It appears from Table II that the fly-ash mixes are not superior to ~ \" — ~3

The University of Michigan ~ Engineering Research Institute the plain-cement mixes in preventing loss of strength with the addition of water. The variations in strength losses are no more than would be expected from such a variable material as concrete. It may be noted that the concrete with 200 pounds of fly ash required slightly less water for the low-slump mixes, and slightly more water for the high-slump mixes, than did the concrete with no fly ash. This difference is very small, slightly more than one gallon per cubic yard of concrete. The conclusion from this study is that the concrete producer must take as much care in controlling the water added to fly-ash concrete as he does with plain portland-cement concrete unless he is willing to accept a sizeable loss in strength with the wet consistency mixes. The lack of strength improvement for the low-slump, 4.5-sack mix containing 200 pounds of ash with respect to the corresponding medium-slump mix at 90 days' age is perplexing. This somewhat parallels the paradoxical behavior noted inProgress Report 2211-6-P wherein a diminished amount of pozzolonic strength gain was observed in the mixes richer in cement. It may be necessary to postulate for mixes having higher ash contents that a certain minimum water content may be required to insure that pozzolonic strength gain will continue. ~ k ______________________________

TABLE I SUMMARY OF RESULTS Nominal Actual. Cement Cement Fly Ash Net Mixing Water Slump Compre'ssive Strength, psi Content, Content, lb/cu yd in 1 Day Days 28Days ay 90 Days 1 Year sk/cu yd sk/cu yd I lb/cu yd gal/sk| 5.47 0 234 5.11 0.8 1482 3213 4178 5238 5.5 5.40 0 259 5.65 4.1 1114 2656 3562 4538 5.36 0 284 6.20 7.9 877 2133 3254 4069 m 4.54 100 234 6.24 0.9 1170 2963 4223 5547 4.5 4.51 100 258 6.86 3.9 908 2513 3646 4933 4.44 100 288 7.68 7.8 698 1966 3188 42.33 4.56 200 230 6.14 1.2 1151 2753 4243 5459 4.5 4.49 200 264 7.04 4.1 853 2235 4010 5464 4.44 200 295 7.86 8.1 619 1773 2972 4541 ~"~__________________3r e~ e-f eC ~~~~~~~~~,".......'.,....,-,..... i,,,. _~~~~~~~~~~~~~~~~~~~~~~~~r

The University of Michigan ~ Engineering Research Institute TABLE II LOSS IN COMPRESSIVE STRENGTH OF NON-AIR ENTRAINED PLAIN AND FLY-ASH CONCRETE DUE TO ADDED WATER Cement Fly Ash Loss of Compressive Strength Between Content, Content, Wet and Dry Consistency Mixes, psi sk/cu yd lb/cu yd 1 Day Days 28 Days 90 Days 5o 5 0 605 1080 924 1169 4.5 100 472 997 1035 1314 4 5 200 532 980 1271 918 6

APPENDIX

TABLE I-A 5.5-SACK REGULAR-CONCRETE DATA-LOW, MODERATE, AND HIGH SLUMPS Actual Cement Material Proportions Weight of Batch Date MadeFly Ash, Content cu W/C, Fresh Slump, Compressive Strength, psi Date Made Content V lb/cu yd No. lb/cu yd sk/cu Sand Gravel Water gal/sk Concrete, in. 1 Days 27 Days Days 90 Days Year...... _______c ySandGravel NIet_ Water lb/cu ftO 371 3-28-56 o 5.47 0.64 1457 1815 228 4.97 149.8 1-1/4 1370 3425 4665 5740 12~8 3250 4575 5565 392 5-14-56 0 5.45 0.64 1481 1815 232 5.05 150.1 1/4 1570 2935 3850 5335 1580 5040 4275 5230 398 5-21-56 o 5.48 0.64 1446 1815 243 5.30 150.1 1 1550 3235 3710 4945 1535 3390 3995 4610 Average 0 5.47 0.64 1461 1815 234 5.11 150.0 0.8 1482 3213 4178 5238 co 372 3-28-56 0 5.46 0.64 1457 1815 243 5.31 150.0 5-1/4 975 2810 3920 4450 955 2630 385 4490 m 393 5-14-56 0 5.34 0.64 1481 1815 269 5.86 148.5 2-3/4 114 2740 5250 4680 1125 2650 3425 4700 * 399 5-21-56 0 5.4 0.64 1446 1815 264 5.77 149.1 4-1/4 1235 2560 3620 4610 1255 245 3270 4295 Average 0 5.40 0.64 1461 1815 259 5.65 149.2 4.1 1114 2656 3562 4538 373 3-28-56 0 5.34 0.64 1457 1815 280 6.12 148.1 8-3/4 610 1855 3320 3815 665 1875 3305 4100 394 5-14-56 0 5.34 0.64 1481 1815 286 6.24 149.0 7-1/4 935 2015 3215 4185 960 2155 3270 4115 400 5-21-56 0 5.41 0.64 1446 1815 286 6.24 149.9 7-3/4 0ooo 2455 3445 4065 logo1090 2440 2970 4135' Average 0 5.36 0.64 1461 1815 284 6.20 149.0 7.9 877 2153 3254 4069 **Denotes volume of dry-rodded coarse aggregate per unit volume of concrete. ~.....,, ~,,,,,,, i,~~~~~~~~~~~~~

TABLE II-A 4.5-SACK REGULAR-CONCRETE DATA-ST. CLAIR FLY ASH-LOW, MODERATE, AND HIGH SLUMPS Actual Cement Material Proportions Weight of Batch AcualCmntMaeiasPoorios w/C, Fresh Slump Compressive Strength psi ^^Date Made ^ ^ Content V^ lb/cu yd / " Poprs^ Srnt p ~ No. lb/cuD yd Co nten l c yd gal/ski Concrete, in. 1 Day 7 Days 28 Days 90 Days 1 Year lb/cu ~sk/cu yd ~ Sand Gravel Net Water I ________________________'____ _____ {_I__________________ rlb/cu ft 0 374 4-2-56 100 4.49 0.75 1132 2126 252 6.71 150.9 3/4 1185 2970 4170 5570 1180 3200 4275 5370 380 4-18-56 100 4.57 0.75 1097 2126 224 5.97 11.3 1 1100 2845 4455 5865 1075 5005 4415 5900 389 5-9-56 100 4.55 0.75 11o8 2126 226 6.03 150.9 1 1255 286o 5815 5405 1245 2895 4225 5370 Average 100 4.54 0.75 1112 2126 234 6.24 151.0 0.9 1170 2963 4223 5547 ~ \ 575 4-2-56 100 4.48 0.75 1132 2126 274 7.50 151.4 4 1020 2440 3535 4680 955 2615 3695 46o0 381 4-18-56 100 4.54 0.75 1097 2126 243 6.47 150.7 4 820 2510 3655 4965 860 2615 3870 5055 390 5-9-56 100 4.50 0.75 1108 2126 256 6.82 150.4 3-3/4 920 2510 3695. 5090 875 2385 5425 5245 Average 100 4.51 0.75 1112 2126 258 6.86 150.8 3.9 908 2513 5646 4933 376 4-2-56 100 4.41 0.75 1132 2126 297 7.91 149.9 7-1/4 830 2330 3550 4770* 760 2330 3285 4150 382 4-18-56 100 4.48 0.75 1097 2126 275 7.54 150.0 7-5/4 550* 1855 5520 4490 660 1875 3270 4380 591 5-9-56 100 4.44 0.75 1108 2126 292 7.79 149.6 8-1/4 630 1730 2825 3940 61o 1695 2880 4205 Average 100 4.44. 0.75 1112 2126 288 7.68 149.8 7.8 698 1966 3188 4233 *Not included in average. **Denotes. volume of dry-rodded coarse aggregate per unit volume of concrete.

TABLE III-A' 4.5-SACK REGULAR-CONCRETE DATA-ST. CLAIR FLY ASH-LOW, MODERATE, AND HIGH SLUMPS Actual Cement Material Proportions Weight f o Batch ate Made Fly Ash, Content V lb/cuyd W/, Fresh Slump Compressive Strength, psi No. b/cu yd sk/cu yd Sand Gravel Net Water /sk Concrete, in. lb/cu ft 1 Day 7 Days 128 Days 90 Days 1 Year 377 4-4-56 200 4.58 0.81 824 2296 219 5.85 151.1 1-1/4 1175 2685 4400 5300 1140 2720 4505 5655 383 4-30-56 200 4.55 0.81 844 2296 243 6.47 151.8 1-1/2 1085 2880 4150 5740 1135 2825 4100 5620 395 5-16-56 200 4.56 0.81 835 2296 229 6.10 151.2 3/4 1165 2755 4150 4945 1205 2650 4150 5495 H Average 200 4.56 0.81 834 2296 230 6.14 151.4 1.2 1151 2753 4243 5459 0 378 4-4-56 200 4.52 0.81 824 2296 254 6.78 150.6 3-3/4 795 2525* 4240 6005 830 2175 4170 5565 r 384 4-30-56 200 4.48 0.81 844 2296 267 7.12 150.4 4-1/4 840 2210 4010 5530 880 2365.4135 5210 396 5-16-56 200 4.47 0.81 835 2296 271 7.22 149.7 4-1/4 885 1945* 3885 5230 890 2190 3620 5245 Average 200 4.49 0.81 834 2296 264 7.04 150.2 4.1 853 235 4010 5464 379 4-4-56 200 4.46 0.81 824 2296 284 7.56 149.4 8 575 1625 2860 4330 585 1645 2670 4415 385 4-30-56 200 4.44 0.81 844 2296 294 7.83 149.9 7-3/4 650 1855 3180 4910 635 1835 3270 4700 C 397 5-16-56 200 4.41 0.81 835 2296 306 8.18 149.0 8-1/2 635 1875 2740 4490 635 1800 3110 4400 r Average 200 4.44 0.81 834 2296 295 7.86 149.4 8.1 619 1773 2972 4541 *Not included in average _ **Denotes volume of dry-rodded coarse aggregate per unit volume of concrete. I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~r