Effects of calcined coal gangue （CG） aggregates treated by the surface thermal activation on the flowability and strength, and paste-CG aggregate interfaces of the cement-based material were investigated. The experi...Effects of calcined coal gangue （CG） aggregates treated by the surface thermal activation on the flowability and strength, and paste-CG aggregate interfaces of the cement-based material were investigated. The experimental results show that the compressive and flexural strength of the cement-based material with the calcined CG aggregates is much higher than that of the material with the natural CG aggregates, but the flowability of the material with calcined CG is significantly reduced with the calcined time. The strength of the material with the calcined CG aggregates only increases little with the calcined time at the same w/c ratio, but is reduced with the calcined time at the same flowability. The CG aggregates calcined by the surface thermal activation obviously overcomes the disadvantages of fully calcined CG.展开更多
This paper investigates the feasibility of using coal gangue as coarse and fine aggregates in concrete as well as how the coal gangue aggregate grading affects concrete properties. Nine mixed concrete samples were pre...This paper investigates the feasibility of using coal gangue as coarse and fine aggregates in concrete as well as how the coal gangue aggregate grading affects concrete properties. Nine mixed concrete samples were prepared with the value n in Fuller＇s curve ranged from 0.44 to 0.68. The coal gangue aggregate with n = 0.62 shows the highest density, water absorption, cylinder strength and the lowest voids. The results indicate that using coal gangue as coarse and fine aggregate in concrete is tech- nically feasible and useful. When n is 0.62, the values of the slump, 28-day compressive, splitting tensile strength, flexural strength and elasticity modulus of coal gangue concrete reach the highest. The highest 7-day and 28-day compressive strength were 24 MPa and 37 MPa in mix CG7, respectively. It is possible to produce grade 30 coal gangue concrete with coal gangue coarse and fine aggregate.展开更多
Coal gangue(CG)is an environmental waste that faces an urgent demand for disposal in China.The utilization of CG in construction materials has broad application prospects and gained increasing interest.However,the poo...Coal gangue(CG)is an environmental waste that faces an urgent demand for disposal in China.The utilization of CG in construction materials has broad application prospects and gained increasing interest.However,the poor compatibility of polycarboxylate superplasticizer(PCE)with CG powder hinders its efficiency in a wide range of applications.Here,this paper attempts to improve the compatibility of PCE with CG powder in cement paste based on the regulation of aggregation and the adsorption behavior of PCE.Dynamic light scattering(DLS)and fluorescence spectroscopy tests were carried out to understand the improved mechanism.The results indicated that the addition of CG powder increases the ionic strengths of the cement liquid phase,which makes PCE tend to aggregate at a lower concentration compared with no CG powder introduction.Adding(CH_(3)COO)_(2)Cu is beneficial for enhancing the workability of cement paste by reducing PCE aggregation while maintaining the compressive strength of cement specimens.Therefore,(CH_(3)COO)_(2)Cu extra addition can be regarded as an effective and sustainable way to improve the workability of cement paste with CG powder.展开更多
基金Funded by the Major State Basic Research Development Program of China('973'Project,2001CB610705)
文摘Effects of calcined coal gangue （CG） aggregates treated by the surface thermal activation on the flowability and strength, and paste-CG aggregate interfaces of the cement-based material were investigated. The experimental results show that the compressive and flexural strength of the cement-based material with the calcined CG aggregates is much higher than that of the material with the natural CG aggregates, but the flowability of the material with calcined CG is significantly reduced with the calcined time. The strength of the material with the calcined CG aggregates only increases little with the calcined time at the same w/c ratio, but is reduced with the calcined time at the same flowability. The CG aggregates calcined by the surface thermal activation obviously overcomes the disadvantages of fully calcined CG.
基金Supported by the National Natural Science Foundation of China(U126112,11226250)China Postdoctoral Science Foundation(2013M541236)
文摘This paper investigates the feasibility of using coal gangue as coarse and fine aggregates in concrete as well as how the coal gangue aggregate grading affects concrete properties. Nine mixed concrete samples were prepared with the value n in Fuller＇s curve ranged from 0.44 to 0.68. The coal gangue aggregate with n = 0.62 shows the highest density, water absorption, cylinder strength and the lowest voids. The results indicate that using coal gangue as coarse and fine aggregate in concrete is tech- nically feasible and useful. When n is 0.62, the values of the slump, 28-day compressive, splitting tensile strength, flexural strength and elasticity modulus of coal gangue concrete reach the highest. The highest 7-day and 28-day compressive strength were 24 MPa and 37 MPa in mix CG7, respectively. It is possible to produce grade 30 coal gangue concrete with coal gangue coarse and fine aggregate.
基金National Key R&D Program of China,No.2022YFB2602604Qiang Yuan,Systematic Project of Guangxi Key Laboratory of Disaster Prevention and Engineering Safety,No.2022ZDK027,Yi Tian.
文摘Coal gangue(CG)is an environmental waste that faces an urgent demand for disposal in China.The utilization of CG in construction materials has broad application prospects and gained increasing interest.However,the poor compatibility of polycarboxylate superplasticizer(PCE)with CG powder hinders its efficiency in a wide range of applications.Here,this paper attempts to improve the compatibility of PCE with CG powder in cement paste based on the regulation of aggregation and the adsorption behavior of PCE.Dynamic light scattering(DLS)and fluorescence spectroscopy tests were carried out to understand the improved mechanism.The results indicated that the addition of CG powder increases the ionic strengths of the cement liquid phase,which makes PCE tend to aggregate at a lower concentration compared with no CG powder introduction.Adding(CH_(3)COO)_(2)Cu is beneficial for enhancing the workability of cement paste by reducing PCE aggregation while maintaining the compressive strength of cement specimens.Therefore,(CH_(3)COO)_(2)Cu extra addition can be regarded as an effective and sustainable way to improve the workability of cement paste with CG powder.
