Experimental Study On Lime-fly Ash Stabilized Building Solid Waste Macadam In Pavement Base

With the rapid development of traffic,a lot of natural gravel is used in highway construction,which leads to the shortage of natural gravel resources.At the same time,a large number of buildings have been built in our country,and buildings need to be demolished after a certain number of years,which will produce a large amount of building solid waste.Most of the building solid waste is treated by landfill,which takes up a lot of land resources and pollutes air and soil.How to reuse construction solid waste has become a hot research topic.This paper focuses on the road performance of replacing natural macadam with construction solid waste,stabilizing with lime and fly ash,and applying it to pavement base.This not only alleviates the shortage of natural gravel,but also solves the problem of building solid waste stacking and realizes the reuse of resources.In order to explore the feasibility of applying lime-fly ash stabilized building solid waste macadam to pavement base,Bailey method was used to determine the gradation of lime-fly ash stabilized building macadam mixture.Then,with the ratio of lime to fly ash,the amount of building solid waste and the proportion of binder as factors,nine groups of mixtures with different proportions were designed by orthogonal test method and orthogonal table L₉（3⁴）.According to the results of 7d unconfined compressive strength test,the best mixture ratio was selected.The compressive strength,90d splitting strength,180d compressive resilience modulus and frost resistance of the mixture at different ages are explored by changing the amount of building solid waste in the optimum mix proportion,and the relationship between compressive strength and splitting strength,compressive resilience modulus and strength after freezing and thawing is established.The research shows that when the content of lime-fly ash exceeds 12%,the structure type of lime-fly ash stabilized building solid waste macadam mixture is suspended and dense.Based on the orthogonal test results,the optimum proportion of seven-day compressive strength of the mixture is analyzed by comprehensive range and variance,and the ratio of lime to fly ash is 1:3,the content of building solid waste is 50%,and the proportion of binder is 30%.The compressive strength,splitting strength,compressive resilience modulus and frost resistance of lime-fly ash stabilized pure macadam mixture are the best.The compressive strength and compressive resilience modulus of the mixture first increased and then decreased with the increase of the content of building solid waste（25%,50%and 75%）,and the compressive strength of the mixture was the highest when the content of building solid waste was 50%.90d splitting strength increases with the increase of building solid waste content,which shows that with the increase of building solid waste content,the anti-deformation coordination ability of base course is improved;The frost resistance of 180d decreases with the increase of building solid waste content,which can meet the requirements of the code,but the influence of low temperature on frost resistance should be considered in practical application.