Laboratory tests, field application and carbon footprint assessment of cement-stabilized pure coal solid wastes as pavement base materials

Abstract

Solid wastes from coal industry, such as coal gangue (CG), coal bottom ash (CBA) and fly ash (FA) from coal-fired power plants, pose a significant impact on the environment. Thus, it is essential to fully study the potential values of these coal solid wastes (CSW) as construction materials. In this study, cement-stabilized FA, CBA and CG were performed as pavement base materials, and the mechanical properties and environmental benefits were systematically investigated in order to achieve the utilization of CSW in road construction. The unconfined compressive strength (UCS) test, splitting tensile strength (STS) test, ultrasonic test, triaxial test, and field application were conducted. The results show that CBA exhibits a negative effect on the early strength of the mixtures. However, the negative effect gradually decreases with the extension of the curing age. In addition, the relationship models between UCS and STS, between UCS and amplitude, between peak stress, peak strain and confining pressure with different CBARR and cement content were proposed. Based on the Mohr-Coulomb (M-C) failure criterion, the unified function expression and parameter-related function expressions with various CBARR and cement content of the shear stress τ were established. The laboratory tests indicate that the mixture with CBARR of 50% exhibits preferable mechanical performance. Field application and carbon footprint assessment verify that the mixture has great potential to be used as a new eco-friendly pavement base material and meets the technical requirements for heavy traffic of class II highways in China.