Strength attributes of fiber-reinforced lightweight aggregate concrete incorporating Lytag ceramsite under freeze-thaw environment

Abstract

The property of high strength of lightweight aggregate concretes (LWACs) makes them widely applicable in construction. However, a low-temperature environment could accelerate the properties degradation of LWACs. In this paper, the effects of freeze-thaw cycles on the strength behavior of basalt fiber (BF) and polyacrylonitrile fiber (PANF) reinforced lightweight aggregate concrete with Industrial waste ceramsite-Lytag investigated, including cubic and axial compressive strength, splitting tensile strength, flexural strength, and shear strength. Mass loss, relative dynamic elastic modulus (RDEM), scanning electron microscopy (SEM), and computed tomography (CT) were used to analyze the impact of freeze-thaw damage on strength performance and microstructure. The results showed that BF and PANF incorporation significantly affected the residual strength due to their ability to suppress crack growth. The specimens with higher BF and PANF volume fracture had better freeze-thaw resistance properties. Moreover, BF-reinforced LWACs exhibited better freeze-thaw resistance than PANF-reinforced LWACs because BF has superior mechanical properties. The flexural strength indicated the fastest degradation rate after freeze-thaw cycles, while the RDEM revealed the least damage. The freeze-thaw resistance durability of fiber-reinforced LWACs is evaluated based on strength degradation, and the corresponding environment partition of specimens is produced. In order to estimate the strength behavior, the equal-damage strip calculation model is proposed by considering size and loading type effects. The comparison analysis of calculation and test results of strength after freeze-thaw cycles suggested applying the four-sides calculation model for predicting the strength behavior of LWACs.