Effect of carbon fiber on properties of concrete with different W/C and its air‐entraining models

Abstract

AbstractThe addition of carbon fiber can change plain concrete (PC) to a quasi‐ductile material and improve its flexural properties through sharing the tensile stress transduced from concrete matrix. However, the influence rule and its mechanism of air entrained by carbon fiber on properties of concrete with different water to cement ratios (W/C) is not clear at present. Therefore, this research aims to explore this influence rule and mechanism. Eighteen kinds of concrete samples with W/C of 0.25, 0.3, and 0.45 including 216 specimens in total were studied. Their mechanical and permeability‐related properties were tested, and carbon fiber's air‐entraining models were established. The results show that carbon fiber has effect of improving the flexural strength, compressive strength, and impermeability of concrete with W/C of 0.25, but when W/C increases, the effect of carbon fiber on improving the flexural strength, reducing the compressive strength and impermeability of concrete increases. The calculation results of the air‐entraining models suggest that one possible air‐entraining mechanism of carbon fiber can be summarized as that carbon fiber entrains more air into concrete as W/C increases, and another one can be summarized as that the air entrained by carbon fiber increases the connectivity of the pore structure of concrete.