Performance of Fiber-Reinforced Lightweight Self- Consolidating Concrete Exposed to Wetting-and-Drying Cycles in Salt Water

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Title: Performance of Fiber-Reinforced Lightweight Self- Consolidating Concrete Exposed to Wetting-and-Drying Cycles in Salt Water

Author(s): Sherif Yehia, Sharef Farrag, and Omar Abdelghaney

Publication: Materials Journal

Volume: 116

Issue: 6

Appears on pages(s): 45-54

Keywords: lightweight concrete; long-term evaluation; scanning electron microscopy; self-consolidating concrete; synthetic polypropylene fibers

Date: 11/1/2019

Abstract:
The durability of lightweight concrete (LWC), especially in the long term, is an essential factor for its successful implementation in structural applications. The use of supplementary cementitious materials (SCMs) and/or fibers changes the interaction between concrete constituents at a microlevel, which might improve durability. In this paper, the mechanical properties and durability aspects of fiber-reinforced, self-consolidating, high-strength, lightweight concrete were evaluated. Concrete specimens were exposed to wetting-and-drying cycles for 1 year in salt water to simulate chloride attack present in the United Arab Emirates and then were compared to control specimens. Results of the compressive strength, flexural strength, and modulus of elasticity are presented and discussed. In addition, scanning electron microscope (SEM) scans and rapid chloride permeability test (RCPT) were conducted. Results showed that the inclusion of fibers alters the microstructural features of concrete; hence, a different chloride resistance mechanism is introduced. Nevertheless, inclusion of fibers did not lead to an increase in chloride permeability. At 1 year, there was an ~3% and 10% reduction in compressive strength in the exposed plain and the fiber-reinforced mixtures, respectively, compared to the non-exposed mixtures. However, fibers significantly enhanced the flexural strength of lightweight concrete (up to an ~100% increase) compared to plain mixtures. In addition, cracks were ~80% smaller in the fiber-reinforced mixtures compared to the plain mixture.