Effects of w/c ratio and curing conditions on strength development in BRECEM concretes

The early strength development of 'BRECEM' concretes, made from 50:50 mixtu res of calcium aluminate cement (CAC) and ground granulated blastfurnace sl ag (ggbs), using 100-mm cubes at w/c ratios of 0.35 and 0.45, has been stud ied. BRECEM concretes showed good strength development at both w/c ratios w hether water cured or air cured. In contrast, longer-term studies with I-m cubes cured under near-adiabatic conditions have indicated that mass BRECEM concretes of similar binder composition may gain compressive strength rela tively slowly. This is primarily due to the heat of hydration of the CAC co mponent, which can lead to temperatures of up to 60 degreesC, resulting in rapid hydration and conversion of the calcium aluminate component. However, the performance of 40 CAC/60 gbs concrete under these near-adiabatic condi tions has proved to be satisfactory over a period of 5 years, with similar strength development to that of equivalent 100-mm cubes stored under ambien t conditions. (C) 2001 Building Research Establishment. Published by Elsevi er Science Ltd. All rights reserved.