Drying shrinkage properties of fiber-reinforced alkali-activated slag and their correlations with microstructure

• Published in: Construction & building materials 2024-01, Vol.411, p.134669, Article 134669
• Main Authors: Chottemada, Pujitha Ganapathi, Rodriguez Sanchez, Jesus, Kar, Arkamitra
• Format: Article
• Language: English
• Subjects: Alkali activated slag; Drying shrinkage; Fiber reinforcement; Microstructure
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.134669

The superior strength, durability, and environmental sustainability of alkali-activated slag (AAS) systems renders it a viable alternative to those based on Portland Cement (PC). However, drying shrinkage in AAS systems is a highly complex process requiring extensive testing. Several studies have reported the incorporation of fibers to AAS systems as an effective way not only to enhance its strength but also to reduce its drying shrinkage, but the information is scattered. In pursuance of this objective, the present study investigates the impact of incorporating steel, polypropylene, polyvinyl alcohol and glass fibers at varying volume fractions from 0.1% to 0.3% on both mortar and concrete AAS specimens. According to the findings, incorporating fibers to AAS concrete increased its compressive strength by up to 13% when compared to the plain mix. A higher volume fraction of 0.3% for steel and glass fiber inclusions significantly minimized the drying shrinkage of AAS concrete by 27% and 31%, respectively. However, due to the increased heterogeneity and subsequent void formation in fiber-reinforced AAS systems, it was noted that the mass loss resulting from the loss of moisture is greater in these cases. Despite the greater mass loss at earlier ages, the fibers in AAS specimens demonstrated their ability to restrain the shrinkage strains. The microstructural studies, which distinctly depict the morphology of AAS paste and the interaction between the fibers and matrix, further validate these conclusions. •Compressive strength of AAS concrete is enhanced by 13% with 0.3% steel fibers.•Glass fibers lead to maximum drying shrinkage reduction of 31% in AAS concrete.•Higher dosage of PP and PVA fibers are detrimental to drying shrinkage properties.•Increased heterogeneity in fiber-reinforced AAS systems lead to greater mass loss.•Enhanced fiber-matrix bond is evidenced with both steel and glass fibers.