Effects of dosage and modulus of water glass on early hydration of alkali-slag cements

This paper examines the early hydration of alkali-slag cements activated with water glass with different n moduli and sodium metasilicate (Na2SiO3-5H(2)O) in solution at 25 degreesC. The early hydration of alkali-activated blast furnace slag cements has been studied using isothermal conduction calorimetry. The cumulative heat of hydration increases by increasing the n modulus as well as the dosage of water glass, but is still lower than that of Portland cement. The compressive strength of normal-cured water glass slag cements is higher than Portland cement mortars. Drying shrinkage of alkali-slag cements is considerably higher than that of Portland cement. Consequently, industrial use of alkali-slag cement needs better understanding of the hardening mechanism and requires further research based on presented observations and results. (C) 2002 Elsevier Science Ltd. All rights reserved.