Road performance analysis of cement stabilized coal gangue mixture

Abstract

In order to solve the environmental pollution of coal gangue and the shortage of aggregate resources in road engineering, waste coal gangue is used as road base material instead of natural stone materials. Through physical, mechanical, chemical and activity tests of coal gangue aggregate, the optimal gradation composition of unconfined compressive strength was determined. Through unconfined compressive strength, indirect tensile strength, flexural tensile strength, freeze-thaw and dry shrinkage tests, the influence of cement content on road performance of cement stabilized coal gangue mixture was studied. By means of SEM, ICP AES, XRD and optical digital microscope, the difference between spontaneous combustion coal gangue and Unspontaneous combustion coal gangue was analyzed, the microstructure of cement stabilized coal gangue mixture was characterized, and the strength formation mechanism of mixture was explored. The results show that Spontaneous combustion coal gangue has higher activity than Unspontaneous combustion coal gangue. Based on the selected optimal allocation (BNS:SNS:SSC = 71.26:9.41:18.8). The mixture of 4% cement dosage can not only meet the requirement of early strength 4.16 MPa, but also show an efficient strength growth rate of 36.10%, showing the optimum mechanical properties. The total shrinkage coefficient of cement stabilized coal gangue mixture with 4% cement dosage is 1.12 × 10−2, which shows that the dry shrinkage resistance is the best. With the increase of time, hydration degree is gradually deepened, and gelled substance is more tightly bonded to aggregates. There is no obvious gap between aggregates, and the integrity of the mixture is enhanced, which can show better road performance. Ca (OH)2, a cement hydration product in cement stabilized coal gangue mixture, takes place pozzolana reaction with active SiO2 and Al2O3 in coal gangue to produce gismondine, which is beneficial to the global strength and the bond quality of the mixture.