Quantifying the performance of macrosynthetic fiber reinforcement and shrinkage reducing admixtures in large scale concrete slabs
Abstract
An inherent characteristic of concrete is the tendency for it to change volume. If this volume change is restrained, residual tensile stresses will be induced, ultimately leading to crack formation. Concrete placed in slabs-on-grade applications, i.e., sidewalks, roadways, and parking lots, are especially susceptible to cracking. Welded-wire fabric is commonly used to provide reinforcement and control the cracking behavior of concrete. However, in the last several decades, the use of fiber-reinforced concrete and shrinkage-reducing admixtures have gained acceptance as an alternative to crack controlling measures. Current standard laboratory testing procedures for quantifying the shrinkage and cracking tendency of concrete provide a convenient means to evaluate these effects using small scale specimens. These small scale test methods do not fully represent the behavior of concrete in the field. This thesis describes a large scale, restrained slab testing system that is designed to simulate full scale performance under standard drying conditions. The large scale slab system allows for a direct comparison between welded wire fabric, fiber reinforcement, and shrinkage-reducing admixtures in their ability to control crack formation and transfer of tensile stresses across the crack. The restrained slab data of this research was able to show the benefits of fiberreinforced concrete and shrinkage reducing admixtures over the welded wire fabric. Furthermore, the slab system is able to monitor stress transfer across a crack through the measurement of crack width over time and provide a quantitative means to evaluate the effectiveness of crack controlling treatments.
Degree
M.S.C.E.
Advisors
Weiss, Purdue University.
Subject Area
Civil engineering|Materials science
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