Research On Road Performance Of Cement Red Mud Stabilized Crushed Stone Base Material

Red mud produced by industrial aluminum is a kind of solid waste,its long-term stacking causes huge environmental pollution and waste of land resources.Although domestic and foreign scholars have done a lot of researches on its recycling,the utilization rate of red mud is still very low.At the same time,the semi-rigid base of cement stabilized macadam has been widely used due to its advantages of high strength,good durability and strong integrity.Applying red mud to cement stabilized macadam will effectively alleviate many problems caused by red mud and save a lot of aggregates,which has a high feasibility.In this paper,based on the study of the physical and chemical properties of the cement red mud stabilized gravel composition materials,the framework-compact structure is selected as the aggregate structure type,and the red mud is added by the external mixing method.20 kinds of mixing ratio schemes were designed by orthogonal test method,and indoor components were built based on the optimal moisture content and maximum dry density obtained by heavy compaction test.Based on the 7d unconfined compressive strength of the test piece as the performance index,the optimal cement dosage is 5% and the red mud content is 0%,10%,20% and 30% respectively.And conduct indoor performance tests such as unconfined compressive strength test,split strength test,bending strength test,uniaxial compression modulus test,freeze-thaw cycle test,dry shrinkage test,temperature shrinkage test,etc.To study the effect of red mud content on the road performance of cement red mud stabilized crushed stone.Based on the results of the indoor performance test,the most representative set of ratios was selected for further performance verification.Due to limited conditions,the test road could not be paved temporarily.This paper designed an outdoor square mold forming method to simulate the test road and standardized the construction process.The study found that proper addition of red mud can effectively improve the road performance of cement red mud stabilized crushed stone.Red mud can promote the formation of early strength of cement red mud stabilized crushed stone.When the red mud content is 10% and 20%,the 7d unconfined compressive strength of the test piece increases by 19.7% and 18.2%,respectively,the splitting strength increases about 20 %.The test piece with a red mud content of 10% is about 9.1% higher than the uniaxial compression modulus of a water-stable test piece;the addition of red mud can also effectively improve the bending strength of the test piece,but its impact on frost resistance is not affected and can be ignored.In addition,the addition of red mud will have a certain negative effect on the shrinkage performance of cement red mud stabilized crushed stone.The proportion of fine aggregates such as red mud in the specimen increased and the structural changes caused the dry shrinkage and temperature shrinkage properties of the specimen to be reduced to varying degrees.According to the analysis of the strength and deflection value measured after the core is cured for 7 days,the test results show that the square mold made of cement red mud stabilized crushed stone It has the advantages of high strength,strong integrity and good uniformity.The results of indoor performance test and outdoor square mold forming test of cement and red mud stabilized macadam show that cement and red mud stabilized graded macadam has good road performance and can be used in large-scale pavement base construction.Based on the factors such as highway grade and utilization rate of red mud,the recommended red mud content is 10%?20%.