Influence of chopped basalt fibers on the fracture performance of concrete subjected to calcium leaching

Abstract

Calcium leaching is one of the major causes of concrete structure failure in soft water environments. In this study, acceleration leaching and three-point bending (TPB) tests were conducted on single-notched TPB specimens to investigate the influence of chopped basalt fibers (CBF) on the fracture performance of concrete subjected to calcium leaching. The fracture-related parameters such as crack initiation and maximum loads, fracture toughness, elastic modulus, tensile strength, and fracture energy of CBF concrete (with ten different fiber length and volume dosage addition combination schemes) under calcium leaching effect were determined and compared based on the test results. Furthermore, the mechanism of CBF for improving the crack and leaching resistance of concrete were analyzed based on the stress intensity factor superposition method and microscopic test results. The results show that a suitable combination of CBF length and volume dosage can effectively improve concrete fracture resistance when subjected to calcium leaching. Too long and excessive fiber additions can result in increased concrete weaknesses, as well as fiber agglomeration and crossover, making CBF less effective in enhancing concrete resistance to calcium leaching and fracture. The addition of CBF to concrete with a length of 6 mm (i.e., aspect ratio is 400) and a volume dose of about 0.35% was determined to be the optimal scheme for improving concrete’s resistance to calcium leaching and fracture, and the comprehensive performance of concrete was improved by approximately 17.68% with this scheme.