Prevention of Autogenous Shrinkage in High-Strength Mortars with Saturated Tea Waste Particles.

Abstract

The purpose of this study was to prevent early age autogenous shrinkage in high-strength mortars with saturated tea waste particles. In general, high strength and high performance concretes are made with low water/binder ratios; hence, they are susceptible to shrink at early ages. This shrinkage occurs due to self-desiccation that leads to autogenous shrinkage. To overcome self-desiccation problems in high-strength cement composites, it is necessary to keep the composites moist for a long time. Pre-saturated porous lightweight aggregates and super absorbent polymers are the most commonly used materials in high-strength cement composites to keep them moist for a long time; however, in this study, porous tea waste particles were used to keep the cement mortars moist. Pre-saturated tea waste particles were used in two different size proportions, making up as much as 3% of the volume of the binder. Moreover, commonly used lightweight aggregate (perlite) was also used to compare the outcomes of specimens made with tea waste particles. Different parameters were observed, such as, flow of fresh mortars, autogenous shrinkage, mechanical strengths and microstructure of specimens. The addition of tea waste and perlite particles in mortars made with Ordinary Portland cement (OPC) as the only binder, showed a reduction in flow, autogenous shrinkage and mechanical strengths, as compared to mixes made with partial addition of silica fume. Although, the use of silica fume improved the mechanical strength of specimens. Moreover, the use of saturated tea waste and perlite particles also improved the microstructure of specimens at an age of 28 days. The results revealed that the saturated tea waste particles have the ability to prevent autogenous shrinkage but they reduce strength of high-strength mortars at early ages.