Influence of a Stepped Heat Curing on the Performance of High-Strength Portland Pozzolana Cement–Based Mortars

Abstract

Abstract In this study, the effects of a stepped heat curing regime originally developed for the Indian conditions on the performance properties of high strength cementitious mortars (HSCMs) containing portland pozzolana cement (PPC) were evaluated. Six mixtures were cast without and with heat curing, including two control mixtures (CM-NC and CM-HC), two silica fume mixtures (SF-NC and SF-HC), and two rice husk ash mixtures (RHA-NC and RHA-HC). Results indicated that stepped heat curing improved the 7-day strength of all mixtures substantially, but mixtures were unable to maintain very high strength levels up to 28 days. The 28-day strengths of heat-cured specimens were comparable with that of the respective normal water-cured specimens. The trends obtained for flexural, impact, and dynamic split tensile strengths supported the compressive strength trends. The durability properties of mixtures were affected to some extent by the use of high temperature for longer duration despite certain improvements in their matrices. Thus, longer durations of high temperature of 200°C up to 48 h should be avoided for HSCMs containing PPC. Under normal water and heat curing, the addition of SF and RHA lowered the early-age compressive strength of HSCMs, whereas at 28 days, their strength and durability improved. In addition, the performances of SF and RHA mixtures were comparable to each other.