Strength and Shrinkage of Natural Pozzolanic Mortar in Hot Weather

Abstract

Natural pozzolans (NP) have been introduced as partial cement replacement to minimize some durability problems encountered with ordinary portland cement (OPC) use in the Arabian Gulf. However, NP addition affects concrete drying shrinkage and leads to a slower strength development, which makes a longer curing time necessary. This research compares the strength and drying shrinkage of NP mortar cured under hot‐weather Gulf conditions and under normal conditions. The effect of various NP replacements was also evaluated in this study. Under hot weather, results showed that OPC mortar generally maintained higher strength than NP mortars. Also, under hot weather, mortar strength increased in early ages at a higher rate than that of normally cured mortars. However, the strength of these hot‐weather samples declined at later ages, while normally cured ones maintained their strength increase. Shrinkage results showed that normally cured NP samples have lower shrinkage values than those of OPC. However hot‐weather NP samples showed early higher shrinkage values than OPC; but later, at one year of age, all samples showed approximately equal values. Moreover, shrinkage of hot‐weather NP samples decreased as their initial normal curing periods increased.