Mechanical Properties of Reactive Powder Concrete with Coal Gangue as Sand Replacement

Abstract

Coal gangue (CG) represents a huge amount of industrial solid waste in China, and usually is used as a coarse aggregate to produce low-strength coal-gangue-based concrete. In this paper, in order to prove the possibility to obtain a higher-strength concrete with a higher CG utilization rate, reactive powder concrete (RPC) with coal gangue as a sand replacement at different replacement ratios was studied. RPC samples were prepared by replacing natural river sand (RS) with CG sand at different CG/RS weight ratios from 0–100% at intervals of 25%. Mechanical tests were carried out, and the microstructure features of RPC samples at 28 days were characterized. The test results showed that strong back shrinkage of strength existed. On days 7 and 14, the flexural strengths of samples with CG/RS replacement ratios of 0–75% fluctuated around the mean value. Strengths of samples with a CG/RS replacement ratio of 100% dropped off. However, on day 28, the flexural strengths of samples with CG were all lower than the strengths of samples on days 7 and 14. The flexural strengths and compressive strengths of the RPC with a CG/RS replacement ratio of 100% on day 14 were 14.09 MPa and 37.03 MPa, respectively, which decreased to 6.42 MPa and 28.44 MPa, respectively, on day 28. Compared with natural river sand, CG sand reduced the working performance, compressive strength, and flexural strength of RPC. Microscopic analysis showed that on day 28, increasing the CG replacement ratio could inhibit cement hydration, weaken the interface transition zone, and lead to the degradation of the RPC’s performance. Modification of CG sand would be helpful to obtain higher-strength concrete.

Degradation Mechanism of Coal Gangue Concrete Suffering from Sulfate Attack in the Mine Environment

“…Thus, the eco-friendly utilization of coal gangue becomes an urgent issue. Extensive research has demonstrated that coal gangue can be effectively used as a substitute for partial cementitious powder, fine or coarse aggregate in concrete, which not only alleviates the problem of deposited coal gangue but also reduces the exploitation of river sand and natural gravel [ 4 ]. Yu, et al [ 5 ] used coal gangue to entirely replace fine and coarse aggregate, preparing coal gangue concrete (CGC) of C30–C50 grade.…”

Investigation of the Impact of Glass Waste in Reactive Powder Concrete on Attenuation Properties for Bremsstrahlung Ray

“…It is more durable and also has better mechanical properties than regular concrete [2,3]. Wen L., et al [4] investigation focused on the mechanical and micro structural characteristics of RPC samples. In order to create RPC samples, coal gangue sand was substituted for natural river sand at various weight ratios ranging from 0 to 100% at intervals of 25%.…”

Influence of Rock Dust Additives as Fine Aggregate Replacement on Properties of Cement Composites—A Review

“…There is a sort of material that can be utilized not only as a substitute for cement clinker, but also as a substitute for natural raw materials for the production of building materials [6][7][8][9]. In conjunction with the rapid increase in concrete production, the demands for natural aggregates are also increasing.…”