GRADING DESIGN AND PERFORMANCE STUDY OF STABILIZED GANGUE OF SKELETON-DENSE CEMENT

Abstract

Gangue is a kind of waste rock produced in coal mining. Gangue in different regions has considerably different physicochemical properties. As a road material, gangue has an uneven particle size distribution and breaks easily, so its application in road projects is limited. To increase gangue utilization, a grading range that is applicable to cement-stabilized gangue was established in this study in consideration of the uneven particle size distribution and easy breakage of gangue. The aim was to explore the feasibility of using gangue as a road base. The appropriate mixing ratio of coarse and fine aggregates was optimized based on the grade filling method and the K method in accordance with the results of 7d unconfined compressive strength (UCS). Moreover, the reasonable grading scope of the stable gangue aggregate of skeleton-dense cement was determined. On this basis, experiments were conducted on splitting strength, compressive resilience modulus, and freeze–thaw performance, and the shrinkage characteristics were analyzed. The stable gangue aggregate of skeleton-dense cement was compared with that of the grading-median (GF) mixture recommended by standards. Results demonstrated that the stable gangues of cement formed a skeleton-dense structure when the content ratio between coarse and fine gangue aggregates was 40%–50%. When the cement dosage was 5%, the 7d, 28d, and 90d UCS of the designed grading mid-value (TJ2) increased by 38.03%, 40.13%, and 34.93%, respectively, compared with that of GF. Specifically, the 7d UCS was higher than 3.0 MPa. The 28d TJ2 was 30.13% higher than the GF anti-freezing coefficient, and TJ2 decreased by 35.85% relative to the GF shrinkage coefficient. The cement-stabilized gangue of the designed grading showed better pavement performance than that of the standard recommending grading. These findings provide a theoretical reference for the practical engineering application of cement-stabilized gangue. Keywords: grading, skeleton dense, gangue, mechanical properties, durability