Initial temperature-dependence of strength development and self-desiccation in cemented paste backfill that contains sodium silicate

Advanced knowledge of the effect of the initial temperatures of cemented paste backfill (CPB) on its strength development and self-desiccation ability is needed to provide a rational basis for mixture proportioning as well as the cost-effective design of CPB structures and speeding up of the mining cycle. An experimental testing and monitoring program has been undertaken to determine the influence of various initial temperatures (2 degrees C, 20 degrees C, 35 degrees C and 50 degrees C) on the strength development and evolution of the self-desiccation (measured by the volumetric water content and suction) of the CPB that contains sodium silicate as the admixture (S-CPB) at early ages (up 28 days). The evolution of the temperature, electrical conductivity (gives information about the cement hydration progress), volumetric water content and suction of S-CPB samples with the specified initial temperatures have been monitored for 28 days. Moreover, mechanical tests and microstructural analyses are performed on these S-CPB specimens after specific curing times (6 h, 1 day, 3 days, 7 days and 28 days). The results obtained show that the initial backfill temperature has a significant influence on the curing temperature of S-CPB, its strength development and self-desiccation. Furthermore, the results reveal that the temperature-time history, cement hydration, self-desiccation and strength development of S-CPB are strongly coupled. The initial SCPB and these couplings should be taken into account for a safe and economical design of S-CPB structures and the speeding up of mining cycles. (C) 2016 Elsevier Ltd. All rights reserved.