EFFECT OF FLY ASH ON DEGREE OF CEMENT HYDRATION IN BINDER PASTES

摘要

The test results on degree of cement hydration in fly ash-cement binder paste systems presented in this report indicate the following: 1. The degree of cement hydration (DOCH) of the plain Portland cement pastes can be estimated by determining the non-evaporable water content, which was observed to increase with w/c ratio and curing age. 2. In case of cement pastes, increase of 0.01 in w/c can be expected to cause an increase in DOCH of about 1%. This means that DOCH values of pastes of w/c ratios of x and x + 0.01 can be estimated to bey and (1+0.01)*y respectively, where DOCH of paste with w/c ratio of x is y. 3. The hydration of cement in fly ash-cement pastes was enhanced due to the higher effective water cement ratio. 4. The hydration of cement measured at the age of 56 days was only marginally higher than that at 28 days. Rate of hydration of cement after 28 days was very slow. 5. Considering the test results available in the present study, it can be noticed that addition of 10%, 30%, and 50% of fly ash results in an increase of DOCH by about 10%, 30%, and 25% respectively, of that of paste without fly ash.