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.
Highlights
High-strength concretes (HSCs) and ultrahigh performance concretes (UHPCs) are the most commonly used concretes in today’s construction industry due to their excellent ductility, durability and strengths [1]
The control mix showed an average flow of 230.00 mm, which was high among the remaining 8 mixes that were made with tea waste or perlite particles with Ordinary Portland cement (OPC) as primary binder
235.50 mm, which was high among the mixes that were made with tea waste or perlite particles with silica fume as the secondary binder
Summary
High-strength concretes (HSCs) and ultrahigh performance concretes (UHPCs) are the most commonly used concretes in today’s construction industry due to their excellent ductility, durability and strengths [1]. They are susceptible to early age shrinkage known as autogenous shrinkage due to self-desiccation [2,3,4]. According to Dudziak and Mechtcherine [5], early age shrinkage leads to micro cracking and shows adverse effects on durability and strength properties in HSCs and UHPCs. Aitcin et al [6] anticipated that the autogenous shrinkage in high-performance concretes occurs due to rapid self-desiccation, and found that this was due to low water/binder (w/b) ratios. Jiang et Materials 2019, 12, 2654; doi:10.3390/ma12172654 www.mdpi.com/journal/materials
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