Development of a steel-PVA hybrid fiber SHCC

Over the last two decades, there has been limited research investigating the behavior of Strain-Hardening Cementitious Composites (SHCC) made using polymer fibers at elevated temperatures. These studies show improved residual compressive behavior of SHCC compared to conventional concrete after being exposed to high temperatures. A likely mechanism for this improvement is the creation of supplementary channels in SHCC due to melting of the polymer fibers, allowing vaporized moisture to escape with low internal pressure and reduced spalling. However, the tensile stress and strain capacities of SHCC are significantly reduced at high temperatures due to loss of fiber-bridging. The goal of this ongoing study is to improve the tensile behavior of SHCC at high temperatures by using a combination of polyvinyl alcohol (PVA) and steel fibers. It is of interest to use the steel fibers (which will not melt at high temperatures) to retain at least a part of SHCC’s superior tensile behavior after being subjected to high temperatures. As a first step toward this goal, an experimental program was designed to study the mechanical behavior of mixes with varying amounts of PVA and steel fibers at ambient temperature. The most desirable volume fractions of PVA and steel fibers were determined through simultaneous optimization of tensile ductility and compressive strength. Thus, the development of the steel-PVA hybrid fiber SHCC, which performs similar to traditional SHCC at room temperature but with likely improved mechanical performance at elevated temperatures, is reported in this paper. The residual thermal behavior of this optimum mix will be studied and compared to the standard SHCC in a future study.