Sulfate attack resistance of cement-stabilized crushed gravel base

To address the transverse heaving hazard of asphalt pavement in desert and salinized soil regions in China, an indoor method is proposed for the measurement of the sulfate resistance of cement-stabilized crushed gravel base, in combination with the relevant technical standards of the highway industry. Specifically, the effects of cement types, mineral admixtures, and the initial salt content of the sulfate resistance of the cement-stabilized crushed gravel base were studied using indoor dry and wet cycle tests. The results revealed that for the same initial salt content and standard curing of 7 days, the unconfined compressive strength of the crushed gravel specimens was stabilized by ordinary Portland cement and was similar to that of the ordinary Portland cement mixed with fly ash and it was higher than that of the crushed gravel specimens stabilized by the high belite sulphoaluminate cement. In the dry and wet cycle process, the unconfined compressive strength of the crushed gravel specimens that was stabilized using three kinds of cement increased initially and then decreased with the increase in the dry and wet cycle times. As the initial salt content increased, the peak strength of the specimens decreased, and the strength reduction stage occurred earlier. When the initial salt content inside the specimens exceeded a threshold value, the internal erosion caused by a very small amount of initial salt content increment is more serious than the external erosion.When the initial salt content was constant, the crushed gravel specimens stabilized by the high belite sulphoaluminate cement exhibited the best sulfate resistance, followed by the crushed gravel specimens stabilized by the ordinary Portland cement mixed with fly ash. The crushed gravel specimens stabilized by ordinary Portland cement had the worst sulfate resistance.