Mechanical properties and pore fractal characteristics of alkali-resistant glass fiber lightweight concrete

Traditional concrete materials have high density and are prone to cracking, leading to a shortened service life. This paper uses shale ceramsite lightweight aggregate to address the issue of material self-weight and introduces alkali-resistant glass fiber (AGF) to solve the problem of concrete cracking, thus preparing a new type of alkali-resistant glass fiber lightweight concrete (AGFLC). By using the control variable method, mix proportions with different gradient water-binder ratios (w/b) and AGF contents (V_r) are set to determine the critical threshold of AGF content. Meanwhile, a modified model considering fiber agglomeration effect and interface failure is proposed. Fractal theory is applied to analyze the pore structure of AGFLC. The results show that when V_r=1%, AGFLC has the best crack resistance, and the pore size becomes smaller, which is beneficial to improving the mechanical properties of concrete. Compared with V_r=0%, when V_r=1%, the compressive strength of AGFLC increases by 8.18%~15.89%, the splitting tensile strength increases by 36.40%~52.87%, and the specific strength increases by 2.92%~10.36%. Through the analysis of the fractal dimension of the pore structure, it is found that the ranges of the fractal dimensions D₂ and D₃ of mesopores and macropores are 2.793~2.893 and 2.913~2.959 respectively, and all R² values are greater than 0.90. When V_r=1%, D₂ and D₃ reach their peak values, and AGF can effectively inhibit the propagation of macroscopic cracks, aiming to solve the problem of shortened service life faced by current prefabricated buildings.