Study on the Characteristics of Sandstone and Feasibility to Replace Limestone in Cement Stabilized Macadam Base

Facing the lack of limestone materials in some highway construction areas, the reasonable utilization of local raw materials become more and more concerned. To verify the feasibility of replacing limestone aggregate with sandstone in macadam, comparative analysis of appearance and composition between sandstone and limestone is conducted first. Then the mechanical properties, water stability and micro morphology of sandstone concrete are conducted via the compressive strength test, splitting strength test, water stability test and scanning electron microscope (SEM) test. The results showed that irregular polygonal grains and loose structure were in both limestone and sandstone, but limestone has large particles in local pores. All the mechanical properties of sandstone concrete could meet the specification requirements which provided support for alternative some limestone in cement stabilized macadam base. The strength growth rate with less than 4.0% cement content was not obvious. With curing age increasing, the splitting tensile strength of sandstone concrete with different cement content gradually increased, but the strength growth trend slowed down after 28 days. The porosity and water absorption of sandstone were larger than that of limestone, which affected the mechanical properties of sandstone. In addition, the application of sandstone replacing limestone project was evaluated, and the pavement test results verified the feasibility of sandstone concrete in expressway.