Application Of Recycled Aggregate From Construction Waste Concrete In Asphalt Mixture

With the rapid development of construction industry,a huge amount of construction waste is produced every year in China.At the same time,China is also facing the problems of late start of construction waste recycling and low rate of construction waste resources.In recent years,with the rapid development of road engineering in China,a large amount of natural aggregate is consumed every year.Based on the above factors,it is imperative to strengthen the recycling of construction waste and improve the utilization rate of construction waste resources.The research on the application of construction waste in the field of road engineering at home and abroad mainly focuses on the base and subbase of the road;the research on the road surface mostly focuses on the application of granite recycled aggregate in asphalt mixture,while the research on the application of limestone recycled aggregate in asphalt mixture is relatively less.Most of the concrete blocks in the construction waste in the north of China are limestone.Reasonable crushing technology can produce high-quality recycled aggregate.If these recycled aggregates can meet the relevant technical requirements and can replace some natural aggregates to be used in the asphalt mixture of low-grade highway,it will have a positive significance to strengthen the recycling of construction waste in China.This paper takes this as the starting point to study.Based on the comparative analysis of the production and treatment process of recycled aggregate at home and abroad,this paper investigates and analyzes a comprehensive construction waste treatment plant in Zhangjiakou.The test jaw crusher is used to produce recycled coarse aggregate,and the crushing value,abrasion rate and adhesion grade of recycled aggregate to asphalt are determined to meet the relevant technical specifications.The grading of 0~5mm,5~10mm,10~20mm and mineral powder is determined by screening test,and the comprehensive grading of mineral material is determined by using the method of planning solution.According to the grading of 10-20 mm natural aggregate,the recycled aggregate is used to replace10-20 mm natural aggregate in the proportion of 0%,25%,50% and 75% respectively.Through Marshall stability test and theoretical maximum density test,the best asphalt aggregate ratio of different proportion of asphalt mixture is determined.Four kinds ofasphalt mixtures with different proportion are tested for road performance.The results show that the dynamic stability of asphalt mixture reaches the maximum when the recycled aggregate content is 50%,the low-temperature crack resistance decreases with the recycled aggregate content,and the water stability increases with the recycled aggregate content.In a comprehensive consideration,it is suggested that the amount of recycled aggregate in the actual project should not be more than 50%.