Experimental investigation on flexural and direct shear behaviors of specimens made of lightweight carbon textile‐reinforced cementitious composites

Abstract

Textile‐reinforced cementitious composites (TRCCs) have recently received significant attention in structural engineering as promising retrofitting materials as well as reinforcements for thin and slender structural components. For applicability in the precast industry, the weight of the structural components made of TRCCs is a major concern. In this study, lightweight (LW) TRCC materials were developed and their flexural and direct shear performances were investigated. Carbon fabric is used as the textile reinforcement of the LW TRCCs, and expanded glass aggregates made from industrial refractory materials with fine particle sizes of 0.25–0.5 mm incorporating the mineral admixture (silica fume) are used to develop the LW cement‐based matrix. The main test series in this study include the expanded glass‐to‐binder (EG/B) ratio, surface coating methods used for textile fabrics, and volume dosages of short polyvinyl alcohol (PVA) fibers used to modify the cement‐based matrix. Three main series, including a total of 30 flexural test specimens and 30 shear test specimens, are fabricated and tested. The flexural behavior of LW TRCCs is investigated via four‐point bending tests and the direct shear behavior of LW TRCCs is investigated based on the FIP standard using one shear failure plane. The experimental results indicate that the EG/B ratio significantly affects the overall flexural and shear performances of LW TRCCs, wherein the use of higher EG/B ratios might lead to greater reduction in flexural properties as well as shear properties in the pre‐peak stage. The coating methods employed for fabric surface treatment via epoxy impregnation combined with rough layers are effective in enhancing flexural properties in terms of load and deformation capacity and shear properties in terms of peak stress compared with the counterpart using only the epoxy coating method. Additionally, incorporating short discrete PVA fibers within the LW cement‐based matrix results in outstanding performance due to improvement in bonding quality at the textile/matrix interface, which can be applied as a potential solution for fabricating LW, high‐performance TRCCs.