A model to predict the amount of calcium hydroxide in concrete containing mineral admixtures

This study examines in detail the degree of reactivity of admixtures, such as fly ash and blast furnace slag, and their effect on the levels of calcium hydroxide in cement paste. Experimental results indicate that reactivity between calcium hydroxide and mineral admixture is dependent on the amount of calcium hydroxide and the degree of hydration of mineral admixtures.From these results, a model was formulated to predict the reaction between calcium hydroxide and mineral admixtures, and its validity verified by comparing calculated data with the data from the tests with cement mortar specimens. The calculated values of calcium hydroxide agree well with the test results. The parameters of the prediction model are dependent on the physical and chemical characteristics of mineral admixtures.