Magnesium chloride and sulfate attacks on gravel-sand-cement-inorganic binder mixture

Investigation on the degradation of improved ground is crucial for predicting its life span and performance under unfavorable conditions. In this study, effects of magnesium chloride (MgCl2) and magnesium sulfate (MgSO4) attacks on gravel-sand-cement-inorganic binder mixtures were investigated. Electrical resistivity, free-free resonant column (FFRC) and uniaxial compression tests were performed at different exposure periods, and results showed that saline solutions exert considerable effects on the geophysical parameters of the mixture. As the samples were exposed to chemical attacks, the electrical resistivity and damping ratio increased, while the longitudinal wave velocity and UCS decreased. Especially, the results at 28 days showed that mixtures without inorganic binder lost approximately 40% of its initial strength in MgCl2 and 12% in MgSO4, while samples with inorganic binder (IBS) only lost about 30% and 8% in MgCl2 and MgSO4 respectively. Thus, it is expected that increasing the inorganic binder content in the mixture can enhance the performance of the grout and reduce strength degradation induced by chemical attacks.