Study On The Influence Of Different Waste Glass Content On The Performance Of Pervious Concrete

As a necessary functional material for the construction and development of"sponge city",pervious concrete has very important research significance.The pervious concrete contains a large number of pores and has the problem of low strength.Therefore,using waste glass as the raw material of pervious concrete can not only improve the recycling rate of waste glass,alleviate the problems of urban waterlogging and heat island effect,but also provide a new way to improve the performance of pervious concrete.In this paper,waste glass is added into pervious concrete as fine aggregate to explore the influence of waste glass on various properties of pervious concrete.The target porosity,water-binder ratio,glass sand rate and fly ash content were selected as factors,and four levels of each factor were set for orthogonal test.The influence rules of various factors on the physical and mechanical properties of pervious concrete were studied by range analysis and variance analysis,and the optimal mix ratio considering both compressive strength and pervious properties was selected through comprehensive evaluation and analysis.At the same time,SEM,EDS and XRD tests were conducted to study the effect of hydration of waste glass pervious concrete system.The following conclusions are reached:（1）Through orthogonal test analysis,it is concluded that the influence degree of each factor on the physical and mechanical properties of pervious concrete is as follows:target porosity>glass sand ratio>water-binder ratio>fly ash content.With the increase of waste glass content,the effective porosity and water permeability coefficient tend to decrease.Although the water retention has a decreasing trend,but the decreasing range is small;The cooling ability increased and the temperature showed a decreasing trend.The compressive strength,flexural strength and splitting tensile strength first increase and then decrease.（2）Through the test analysis of water retention and cooling performance,it is concluded that waste glass still has good water retention performance,and the temperature of pervious concrete can be effectively controlled by the small thermal conductivity of glass,which can effectively improve the urban heat island effect.（3）Through comprehensive evaluation and analysis,the optimal mix ratio of pervious concrete with both compressive strength and permeability is obtained as follows:target porosity 15%,water-binder ratio 0.32,glass sand rate 10%,fly ash content 10%.Its compressive strength is 20.59MPa,and its permeability coefficient is 1.46mm/s.All indexes meet the requirements of standard use.（4）According to the microscopic test analysis,the glass has a certain potholanic activity,which promotes the generation of hydration products.With the increase of glass sand content,a large amount of Si O₂in the glass reacts with Ca（OH）₂to generate calcium silicate hydrate（C-S-H）,which improves the degree of slurry compactness,improves the microscopic morphology,and thus enhances the strength of pervious concrete.The volcanic ash reaction of fly ash is mainly in the later stage.With the increase of fly ash content,the overall structure becomes tighter and the strength of pervious concrete increases.However,when the fly ash content exceeds a certain amount,the tightness decreases and the strength of pervious concrete decreases.