Reduction of the calcium leaching effect on the physical and mechanical properties of concrete by adding chopped basalt fibers

Abstract

Calcium leaching is one of the essential diseases of cementitious materials and is a time-varying irreversible process that reduces the structural reliability of concrete. Although some research has found methods to inhibit this phenomenon, various limitations have prevented its widespread application. In this paper, high-performance and low-cost basalt fiber (BF) was used for the first time in an attempt to mitigate the deterioration effect of calcium leaching on the physical and mechanical properties of concrete. The properties such as mass loss, porosity, relative dynamic elastic modulus, and compressive and splitting tensile strengths of concrete (with ten types of BF addition combination schemes) exposed to 6 mol/L ammonium chloride aqueous solution were measured. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) measurements were conducted to investigate the evolution of the micro-structural morphology and composition of concrete during the leaching process. The results show that the addition of an appropriate length and volume dosage of BF to the concrete can effectively mitigate the effect of calcium leaching on the physical and mechanical properties of concrete. The BF with a longer length and a higher volume dosage not only can not mitigate the deterioration effect of calcium leaching but has the opposite effect. Furthermore, the addition of BF with a length of 6 mm and a volume dosage of 0.4 % in concrete was suggested to mitigate the effect of calcium leaching on the physical and mechanical properties of concrete.