Effects of water/powder ratio, mixing ratio of fly ash, and curing temperature on pozzolanic reaction of fly ash in cement paste

The effects of the mix proportion and curing temperature on the pozzolanic reaction of fly ash in cement paste were investigated by examining the productions of calcium hydroxide and the pozzolanic reaction ratio of fly ash. It is possible to accurately determine the reaction ratio of fly ash in cement paste from the insoluble residue and the quantity of dissolved Al2O3. The reaction ratios of fly ash, at the curing temperature of 40 degreesC, the water/powder ratio of 50%, and the substitution rate of fly ash of 40%, are 12% and 32% at the ages of 7 days and 1 year, respectively. The higher the curing temperature or the higher the water/powder ratio is, the higher the reaction ratio of fly ash. The starting time of the pozzolanic reaction at the curing temperature of 20 degreesC is at the age of 28 days or more because the reaction ratio at 28 days is nearly 0%. The pozzolanic reaction of fly ash in cement paste highly depends upon the curing temperature. The reaction ratio of fly ash decreases with an increasing fly ash substitution rate. (C) 2001 Elsevier Science Ltd. All rights reserved.