Cracking resistance and mechanical properties of basalt fibers reinforced cement-stabilized macadam

Abstract

A series of tests studies have been carried out to evaluate the potential impact of basalt fibers on mechanical performance (compressive strength, flexural strength), fracture energy and anti-shrinkage properties of cement-stabilized macadam, which is a kind of popular semi-rigid base and subbase composite material. Four series of cement-stabilized macadam mixtures (the cement contents are 85 kg/m3, 110 kg/m3, 130 kg/m3 and 160 kg/m3) were prepared by incorporating four various dosages (1 kg/m3, 3 kg/m3, 6 kg/m3, 10 kg/m3) of basalt fiber. The optimum basalt fibers length was determined based on the mechanical properties of cement-stabilized macadam mixtures. Then compressive strength test, flexural strength test, fracture energy test, cracking resistance test and scanning electron microscopy (SEM) test were carried out in this study. The results show that addition of basalt fibers can improve the flexural strength, while its effect on compressive strength of cement-stabilized macadam was not remarkable. The maximum deflection in midspan of the specimen was also improved due to the reinforcement effect of basalt fibers. The fracture energy and gain ratio of basalt fibers reinforced cement-stabilized macadam vary nonlinearly with increasing basalt fibers dosage, especially when the basalt fibers dosage was more than 6 kg/m3 where the effect of added fibers on the fracture energy was significant. When the basalt fibers dosage was more than 6 kg/m3, the anti-dry shrinkage properties and cracking ability under temperature cycle of cement-stabilized macadam were both improved effectively. Moreover, the scanning electron microscopy images revealed that the tight bond between basalt fibers and mortar matrix could help the matrix to transfer and share the tensile stress, and consequently, the flexural strength, fracture energy and cracking resistance capacity of cement-stabilized macadam could be improved by the addition of basalt fibers.