Application Of Fine Aggregate Of Recycled Construction Waste Clay Brick In Cement-stabilized Macadam Subbase

With the rapid development of China’s construction industry,more and more construction waste is accumulated due to inadequate existing treatment methods,which brings great pressure to the environment and management.Response to state the latest environmental governance guidelines,this study takes solving environmental governance of the problems of construction waste as the research target to prove that construction waste can be used as a raw material in road engineering with a reasonable and effective application method.Based on the actual use of performance requirements in road engineering,laboratory research was used as the main basis for this study to provide that a safe and reliable experimental scheme existed and the microstructure and micro mechanism of construction waste in the cement stabilized road subbase were also explained in this study.The tests in this paper mainly applied the clay bricks which were less studied among all kinds of construction waste.To apply the clay bricks from construction waste to road engineering in a relatively large number,this study mainly used the clay bricks of construction waste in the form of fine aggregate to partially replace the fine aggregate of natural gravel aggregate for various performance tests.Water absorption and crushing value,the needle flake,apparent relative density,plasticity index,unconfined compressive strength,indirect tensile strength,frost resistance,erosion resistance performance,temperature shrinkage and drying shrinkage performance of were as the research subject of test index,from material properties,mechanical properties and road performance from three aspects,the comprehensive study on the construction waste recycled clay brick aggregate,each test results combined with analytic hierarchy process to get construction waste recycled clay brick application in road engineering with the best solution.Test of each replacement percentages(0%,20%,40%,50%,60%,80%)of the indicators are showing different characteristics of change,overall,with recycled construction waste clay brick partly replace the natural gravel fine aggregate in the cement stabilized road subbase,the unconfined compressive strength with long curing time has bigger growth rate than all-natural aggregate cement stabilized road subbase,and regeneration of clay fine aggregate content,the higher the greater the strength growth.The regenerated clay brick has an obvious enhancement effect on the thermal shrinkage resistance and 180 d freeze-thaw resistance of the cement stabilized road subbase,but according to the difference of replacement rate,the 28 d frost resistance and dry shrinkage resistance of the cement stabilized road subbase are strengthened and weakened respectively.Different from other properties,the indirect tensile strength and erosion resistance did not change greatly when the addition of recycled clay bricks was added in the cement stabilized road subbase.Since the optimal replacement rate is not the same in each test result,this paper selects the analytic hierarchy process which is commonly used in statistics to comprehensively analyze the optimal replacement rate of recycled clay brick fine aggregate for natural aggregate to be 20%.It can be seen from the results of the analysis of cement stabilized structure layer with recycled fine aggregate clay brick that recycled fine aggregate clay brick performance enhancement effect in the cement stabilized road subbase.Using the CT scanning technique and the CPD test combined with XRD and SEM scanning regenerated clay brick composition results,analyzed that construction waste clay brick with potential activity and can be in cement stabilized environment.This potential activity of recycled clay brick aggregate in the cement stabilized road subbase can enhance the strength,improve the performance and weaken the effect of alkali-aggregate effect.