Abstract
To study waterborne frost heaving failure mechanism of coal gangue ceramsite concrete (CGCC) under freeze-thaw cycles, capillary water absorption test, nonmetallic ultrasonic testing test, low-field nuclear magnetic resonance (LNMR) test, N2 adsorption test, and other tests were used to determine the effect of freeze-thaw cycles on the porosity, relative dynamic elastic modulus (RDM), and capillary adsorption rate of different coal gangue ceramsite (MT) replacement rates (0, 20%, 40%, and 60%). Combining the changes of performance indexes and the changes of micropore structure under freeze-thaw cycles, the freeze-thaw failure mechanism of normal concrete (OC) and CGCC was analyzed. In view of the particularity of MT material, the method based on pore size is put forward to distinguish M pores from T pores, and the reasons for different properties are analyzed from the microperspective. The results show that the freeze-thaw cycle changes the microstructure of coal gangue concrete and has an obvious influence on its properties. And when the replacement rate is 40%, degradation mitigation performance is optimal. Due to the particularity of MT shape, T pores are dominant in coal gangue concrete matrix, which is different from the microstructure of ordinary concrete and can reduce the structural deterioration caused by freeze-thaw. The research results of this paper can provide a reference for the research and application of CGCC in freeze-thaw environment.
Highlights
Coal gangue is a kind of solid waste which is associated with coal in the coal formation process
“three north regions” area. erefore, the research focuses on the frost resistance and frost heaving failure mechanism of coal gangue concrete under freeze-thaw cycles
While coal gangue ceramsite has the advantages of low density, light weight, and high strength [9], it is considered to make coal gangue into ceramsite to replace the coarse aggregate in ordinary concrete, in order to slow down the change of pore structure of coal gangue concrete in the freeze-thaw cycle environment
Summary
Coal gangue is a kind of solid waste which is associated with coal in the coal formation process. Erefore, the research focuses on the frost resistance and frost heaving failure mechanism of coal gangue concrete under freeze-thaw cycles. While coal gangue ceramsite has the advantages of low density, light weight, and high strength [9], it is considered to make coal gangue into ceramsite to replace the coarse aggregate in ordinary concrete, in order to slow down the change of pore structure of coal gangue concrete in the freeze-thaw cycle environment. In order to improve this problem, this paper used coal gangue ceramsite to replace parts of coarse aggregate and explored the durability and frost heaving failure mechanism of CGCC through capillary water absorption performance, durability index, and microscopic pore structure change under saturated freeze-thaw cycle action. In order to improve this problem, this paper used coal gangue ceramsite to replace parts of coarse aggregate and explored the durability and frost heaving failure mechanism of CGCC through capillary water absorption performance, durability index, and microscopic pore structure change under saturated freeze-thaw cycle action. is paper aims at providing a reference and basis for the application of coal gangue and improving the frost resistance of coal gangue concrete
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