Study of the microstructure and flexural behavior of cementitious composites reinforced by surface modified carbon textiles

•The microstructure of carbon textile reinforced concretes (TRCs) was studied.•Strain hardening behavior and multiple cracking was obtained for modified samples.•The textile surface modification improved the flexural behavior of the TRCs.•Epoxy resin was a suitable modifying agent for increasing the strength of the TRCs.•SBR latex & Castor oil coated textiles increased the flexural toughness of the TRCs.

In this paper, the effect of surface modification of a carbon textile on the flexural behavior of the textile reinforced fine aggregate concretes was investigated. Three different surface modifying agents (i.e. styrene butadiene latex, hydrophilic oil and epoxy resin) were applied as coating on the carbon textiles at different weight ratios (i.e. 35, 70, and 100% by weight of the textile). The four point bending test was carried out on the samples. It was found that the textile surface modification led to an increase in the ductility of the textile reinforced concretes (TRCs). Utilizing the latex and oil coated textile reduced the post cracking strengths of the TRC samples while the epoxy coated textile led to a considerable increase in the post cracking strength (i.e. in the range of 72-190%). It was also found that the flexural toughness of the epoxy coated textile reinforced concrete improved in the range of 250-780% compared to the uncoated textile reinforced concrete. Meanwhile, it was found that in order to improve the flexural strength and toughness of the TRCs, it is more effective to apply surface modification to the textiles instead of using higher contents of reinforcing textiles. Finally, the interfacial transition zone (ITZ) of the textile and cement based matrix in all the samples was characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy.