Research On Engineering Characteristics Of "Abandoned Clay Brick-red Clay" Subgrade Fillers

With the rapid development of the city,new-style high-rise buildings are rising on the ground,and nearly half of the construction waste generated when a large number of old buildings are demolished are discarded clay bricks.The application of discarded clay bricks to road engineering is a subject of important practical significance.In the practice of highway engineering,red clay,as a special soil,has a high liquid limit and plasticity,so it is not suitable to be used as a subgrade filling directly.Therefore,the "abandoned clay brick-red clay" mixture after using the waste clay brick to improve the red clay is used as the roadbed filler to study its engineering characteristics and provide a theoretical calculation basis for engineering practice.This paper takes the mixture of waste clay bricks and red clay in different proportions as the main research object.Through particle analysis test,compaction test,unconfined compressive strength,elastic modulus deformation,CBR bearing capacity,etc.A series of indoor tests to study the engineering properties of the "discarded clay brick-red clay" mixture of roadbed.The main research results are as follows:(1)The particle analysis test shows that the gradation curve of four different ratios(mass ratio)of the mixture is relatively slow.As the proportion of waste clay bricks increases,the particle size varies greatly,and there is a difference between the waste clay brick aggregate particles and the particles.After mixing with the red clay,the gaps between the particles are filled with small particles,and the particle gradation is good.(2)The compaction test shows that the optimal moisture content of the red clay is 24.6%,and the maximum dry density is 1.59 g.cm-3.When the mixture ratio is 4:6,the maximum dry density is 1.82 g.cm-3,and when the ratio is 2:8,the minimum is 1.76 g.cm-3;the optimal moisture content is 18.46% when the ratio is 2:8.The minimum is 12.8% at 5:5;the dry density of the mixture is greater than that of red clay,and the moisture content is also reduced after mixing waste clay bricks.(3)The resilience modulus of the mixture was studied,and the ratio was 36.7MPa at 2:8,44.9MPa at 3:7,64 MPa at 4:6,and 80.3MPa at 5:5.The optimal moisture content of the mixture is inversely proportional to the resilience modulus,and the resilience modulus gradually increases as the proportion of waste clay bricks increases and the optimal moisture content decreases.When the mixture is used as a roadbed filler,the greater the modulus of resilience,the stronger the resistance to deformation.(4)The unconfined compressive strength of the mixture was studied.When the ratio is2:8,it is 0.61 MPa,3:7 is 0.78 MPa,4:6 is 2.121 MPa,and 5:5 is 1.13 MPa.The dry density is the largest when the bricks account for 40%,and the particles are tightly interlocked,and the compressive strength is the largest.(5)Measure the expansion of the mixture through a dial indicator,and found that under the optimal moisture content conditions,when the proportion of waste clay bricks is between30% and 40%,the expansion of the mixture is small;a certain proportion of waste clay bricks Can effectively reduce the expansion of the mixture;The CBR value of the "waste clay brick-red clay" mixture under the condition of optimal moisture content is 21.5% when the ratio is 2:8,22.6% when 3:7,and 55.4% when 4:6,62.6% at 5:5.The CBR value of the mixture increases as the proportion of waste clay bricks increases.(6)Through research,it is found that when the brick-soil ratio of the mixture is 3:7 and4:6,the engineering performance of the roadbed reaches an optimal state,so the optimal mixing amount of discarded clay bricks is 30% and 40%.