Abstract

The research into the road performance of coal gangue is of great significance for the consumption of coal gangue and reducing pollution. In this paper, the coal gangues were prepared by separation and crushing processes, and their gradations were also optimized. Aiming to identify the possible problems of coal gangue as a pavement base, an unconfined compressive strength test, a splitting test, a freeze–thaw test, and a drying shrinkage test of cement stabilized gangue with varying cement amounts were carried out, and the test results were compared and analyzed. The test results showed that the maximum dry density and optimum moisture content (OMC) of the optimized cement stabilized gangue and cement stabilized macadam increased with cement content. The maximum dry density and OMC of cement stabilized macadam were larger than that of cement stabilized gangue with the same cement content. The optimized 7-day unconfined compressive strength of cement stabilized gangue can meet the requirements for a secondary and lower highway base and subbase. The OMC and cement content are the critical factors affecting the compressive strength loss rate of cement stabilized gangue after freeze–thaw cycles. The smaller the OMC of cement stabilized gangue and the larger the cement content, the lower the compressive strength loss rate. With an increase in cement content, the drying shrinkage strain of cement stabilized gangue increased. The results show that a cement content of 4% is optimal for the cement stabilized coal gangue, which can be used for the light traffic base and heavy traffic subbase of class II and below highways. It provides a basis, guide, and reference for the application of coal gangue materials in a high-grade highway base.

Highlights

  • Coal plays an essential role in the energy supply of China and many countries in the world

  • The results indicated that the strength of soil gangue used as subgrade filler can fully meet the subgrade design requirements

  • The gradation of coal gangue was optimized according to JTG/TF20-2015 “Technical guidelines for construction of highway roadbases” [37] to meet the gradation requirements for a secondary highway base and subbase

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Summary

Introduction

Coal plays an essential role in the energy supply of China and many countries in the world. Coal gangue is produced during coal mining, accounting for almost 10–25% of total coal extraction [1,2,3]. A large number of coal gangues are piled up around mines. More and more coal gangues are piled up, but the total utilization rate is low [4]. The accumulation of coal gangue occupies many valuable land resources and pollutes the soil, groundwater, and air in the accumulation place. A large amount of coal gangue accumulation may cause spontaneous combustion endangering the safety of the public and property. There is an acute need to tackle this underutilization of coal gangue from a sustainability perspective [5,6,7,8]

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