Study on the Performance of Cement-Based Solid Waste Filling Materials in Different Hydration Environments
In order to study the influence mechanism of different hydration environments on the mechanical properties and microstructure of cement-based solid waste filling materials,six kinds of hydration environments were designed,including curing at standard constant temperature and humidity(C1),bagging curing at constant temperature and humidity(C2),curing in natural air(C3),curing in water(C4),curing at 30 ℃(C5),and curing at 40 ℃(C6).The failure patterns of test blocks under different hydration environments were explored,and X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM)were used to analyze the mechanism of hydration products of filling materials.The results show that the curing temperature is a key factor affecting the rapid increase of early compressive strength of the filling body,which can accelerate the dissolution-reconstruction-condensation reaction of aluminosilicate raw materials,increase the output of hydration products ettringite and C-S-H gel,and the products grow rapidly and interweave to fill among the pores of the aggregate,forming a dense three-dimensional structure.Under the C6 hydration environment,the compressive strength of the filling body at 3 d and 7 d reaches the maximum value of 2.08 MPa and 3.07 MPa.However,too high temperature leads to uneven distribution of hydration products,which hinders the dissolution of cementitious active ions and affects the improvement of later strength.The humidity determines the development of the later strength of the filling body,which can provide water molecules for the hydration reaction.When the curing age is 28 d,the compressive strength of the filling body under different hydration environments is ranked as C6＞C4＞C1＞C5＞C3＞C2.
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