Relationship between Compressive Strength and Pore Structure of Hybrid Fiber-Reinforced Concrete Subjected to Carbonation

In order to study the relationship between the compressive strength and pore structure of carbonized concrete, normal concrete (NC), basalt-polypropylene hybrid fiber-reinforced concrete (BPC), and steel-polypropylene hybrid fiber-reinforced concrete (SPC) were prepared. The compressive strength and pore structure of concrete with carbonation ages of 0, 7, 14, 28, and 56 days were tested, and the empirical formulas of total air content-compressive strength were obtained. The results show that the compressive strength can be well predicted from the total air content of concrete through all the empirical formulas of linear, logarithmic, exponential, and power functions. The formulas of air content in specific pore size range and compressive strength of concrete were obtained. The air content of both small and medium pores has a strong negative linear correlation with compressive strength. The applicability of the two formulas is good. Most of the theoretical and measured values deviate within +/- 15%. The air content-compressive strength model based on specific pore size range is more accurate than the total air content-compressive strength model. By summarizing a large number of literature data and analyzing the measured data, this study obtained widely applicable compressive strength-air content relationship formulas, which is of great significance to the compressive strength prediction of normal concrete and hybrid fiber-reinforced concrete.