Study On Performance Enhancement Of Recycled Aggregate Permeable Concrete Based On Silane Modification

With the rapid development of urbanization in China,the demand for concrete is increasing,and the natural aggregate resources are becoming increasingly scarce.The recycling of construction waste has profound significance for the national construction of sustainable development.In addition,our country is speeding up the construction of sponge city and striving to solve the problem of urban waterlogging.Domestic and overseas scholars have preliminarily proved the feasibility of recycled aggregate applied to ordinary concrete.In this paper,recycled aggregate was mainly used in pervious concrete,in order to solve the problem of waste recycling and promote the construction of sponge city.Meanwhile,the mechanical property,permeability and microstructure of silane modified recycled aggregate pervious concrete were systematically studied by combining experimental research with numerical simulation.In view of the fact that recycled aggregate is inferior to natural aggreg ate essentially,a silane modified method of recycled aggregate was proposed to apply in pervious concrete.The effects of silane treatment on the physical and mechanical properties of recycled aggregate were studied based on aggregate to cement ratio and water-cement ratio.Additional water consumption was set as the control group.The experimental results show that the compressive strength of samples treated with silane is higher than that treated with additional water,and the amplitude of enhancement range from 30% to 78% with the increase of aggregate to cement ratio,while the permeability coefficient decreases by 30% ~ 48%.CT scanning of recycled aggregate pervious concrete was carried out,and image thresholding was processed by Mimics.Based on the linear analysis method,the influence of silane modification on cement paste distribution of recycled aggregate permeable concrete was quantified by using MATLAB programming.The results innovatively explain the reason why silane treatment enhances the strength of pervious concrete from the view of cement paste distribution.Due to the indistinguishability of cement paste by CT scanning with a low precision,the method of morphology was proposed to embed cement paste into the image of aggregates under real packing state.Then,three-dimensional meso-model of pervious concrete was built by image reconstruction.Abaqus was used to simulate the uniaxial compression,uniaxial tension and splitting tension of pervious concrete with different paste coating thickness.The results show that the mechanical properties of pervious concrete are closely related to the thickness of paste.The thicker the paste on the aggregate surface,the greater the elastic modulus,the greater the compressive strength and the corresponding peak strain.The stress distribution and fracture development of uniaxial compression nephogram of silane treatment group and additional water consumption group were also studied.The results verify that the recycled aggregate permeable concrete treated with silane is superior to the additional water consumption group in terms of mechanical properties.