Evaluation of the shrinkage properties and crack resistance performance of cement-stabilized pure coal-based solid wastes as pavement base materials

The unclear shrinkage performance of cement -stabilized pure coal -based solid wastes (CSPCBSW) mixture hinders its widespread application in pavement base. Thus, it is crucial to comprehensively investigate the shrinkage performance and clarify the shrinkage mechanism. In this study, the drying shrinkage test, thermal shrinkage test, microstructure detection, evaluation of the crack resistance performance, and field application were performed. The results show that the drying shrinkage strain (DSS) and drying shrinkage coefficient (DSC) have a negative linear correlation with coal bottom ash replacement rate (CBARR) and a positive linear association with cement content. However, the thermal shrinkage strain (TSS) and thermal shrinkage coefficient (TSC) exhibit an opposite variation trend concerning CBARR and cement content. The variation in moisture loss rate, DSS and DSC of the mixtures follow a three -stage pattern: linear growth (0-7 days), gradually slowing growth (8-30 days), and nearly horizontal growth (31-180 days). Increasing the cement content and CBARR effectively reduce the complexity of pore edges and enhance the uniformity of pores. Moreover, the main influencing factors of thermal and drying shrinkage of the mixtures at different stages were revealed. The newly proposed comprehensive crack resistance index was confirmed to be reliable and reasonable via field application. It is recommended that the CBARR of the mixtures should be equal to or greater than 50%. A series of tests verify that the novel eco-friendly green mixture holds significant potential for application in future pavement base.