The hybrid effects of PVA fiber and basalt fiber on mechanical performance of cost effective hybrid cementitious composites

摘要

Unlike conventional concrete materials, micromechanical design theory is used in the material design processes of Engineered Cementitious Composites (ECC). The design theory based on micromechanics paves the way for the use of hybrid fibers in order to improve mechanical properties and reduce production costs since the cost of fibers being one of the main components of ECC is high. The combination of fibers up to a certain ratio in the mixtures triggers high tensile ductility (approximately 3% axial tensile strain capacity) along with narrow crack openings. The aim of the study was to improve the basic mechanical properties of hybrid fiber-reinforced cementitious composites by using PVA fiber and basalt fiber as a hybrid in order to decrease production costs. The total fiber content of 2% was formed with three different proportions of basalt fiber and PVA fiber and the impacts on the mortar properties were examined within the scope of the study. First of all, the ECC control sample consisting of only PVA fiber was produced. Then hybrid fibers were added into the mortar in three different combinations as 75% PVA + 25% basalt fiber, 50% PVA + 50% basalt fiber and 25% PVA + 75% basalt fiber at a total fiber content of 2%. Compressive strength, flexural strength, tensile strength and microstructures analyses were made on the mortars and they were compared with the control sample. The optimum hybrid combination was obtained at 75% PVA + 25% basalt fiber. According to the results of the experimental study, approximate results were obtained with respect to the reference sample in flexural strength of mortars and tensile strength of mortars by increasing PVA fiber ratio in the mixtures. As a result, performance characteristics of hybrid fiber reinforced cementitious composites were affected at different levels due to the mechanical and geometrical properties of the fibers used. (C) 2020 Elsevier Ltd. All rights reserved.