Effect of shrinkage-mitigating materials on performance of fiber-reinforced concrete – An overview

Abstract

Fiber-reinforced concrete (FRC) has been widely used due to its superior mechanical properties, ductility, and cracking resistance. However, fibers cannot completely hinder cracking resulting from shrinkage. The use of shrinkage-mitigating materials, such as expansive agent (EA), shrinkage-reducing admixture (SRA), and saturated lightweight sand (LWS) can be effective in securing FRC with low risk of cracking. The use of EA in the presence of fibers, causes expansion into the concrete matrix, which is counteracted by the fibers. This interaction creates a uniformly compressive pre-stress or self-stress in the matrix, which can limit shrinkage. The counter shrinkage performance can be promoted by shrinkage-reducing admixtures (SRA) or internal curing (IC) by porous aggregate.This paper provides a comprehensive review of studies on the synergetic effect of shrinkage-mitigating strategies on FRC performance. The review indicated that the coupled effect of fibers and EA can moderately enhance mechanical properties of FRC due to the pre-stressing of fibers. Different types of EAs up to 10% mass of cementitious materials, depending on the moist curing duration, can improve compressive and flexural properties. The binary system of various types of fibers and over 1% SRA may reduce mechanical properties and enhance autogenous and drying shrinkage properties, significantly. The addition of EA to the binary system of fiber and SRA can limit the degree of reduction in mechanical properties and reduce autogenous and drying shrinkage. The ternary combination of fiber, EA, and LWS can significantly promote high resistance to autogenous and total shrinkage. Statistical data analysis shows the two-way interactions of Fiber-SRA, Fiber-EA, and Fiber-LWS are significant in affecting compressive strength of FRC. The most important factors affecting the flexural strength of FRC are Fiber-SRA and Fiber-LWS. All of the two-, three- and four-way interactions of these factors have a significant effect on shrinkage properties of FRC. Based on the literature’s results and desirability numbers from the statistical analysis, the optimum contents of EA, SRA, and LWS can range between 5–10%, 1–2%, and 10–25%, respectively.