Study On Mechanical Properties Of Sludge Solidified With Cement And Waste Concrete Granular Material

The mixed soil made of waste concrete particles and cement solidified sludge as foundation treatment materials can not only be used in engineering fields such as soft soil foundation treatment,retaining wall backfilling and slope treatment,but also reduce the pollution caused by waste concrete disposal,better solve the reuse problem of waste concrete,and save a lot of filler resources such as sand and stone.Therefore,it is necessary to understand the basic mechanical properties of waste concrete cement solidified sludge samples,including unconfined compressive strength,deformation and shear strength.Based on the indoor unconfined compressive strength test,the mechanical properties of waste concrete granular material cement solidified sludge are obtained in this paper.According to the unconfined compressive strength test results,the effects of mix proportion parameters(cement content,waste concrete particle content),waste concrete particle size and curing age on the unconfined compressive strength are analyzed,and the unconfined compressive strength test results are analyzed by multiple linear regression analysis.According to the stress-strain curve relationship,the ultimate strain,stress-strain curve characteristics and deformation modulus of waste concrete granular material cement solidified sludge samples are analyzed.Finally,the optimal stress-strain function relationship model is selected.Different normal stresses(50k Pa,100 k Pa,150 k Pa,200 k Pa)were used to carry out indoor rapid shear tests,and the effects of waste concrete particle content and curing age on shear strength were analyzed.According to the test results,the cohesion and internal friction angle are calculated,the relationship between the cohesion and internal friction angle of waste concrete granular material cement solidified sludge and the curing age is analyzed,and the characteristics of shear stress shear displacement curve and the change of water content at different ages are analyzed.The main conclusions of this paper are as follows:(1)The unconfined compressive strength of waste concrete granular material cement solidified sludge sample increases with the increase of cement content;The strength of the sample first increases and then decreases with the increase of the content of waste concrete particles,and there is an optimal content range(12-15%);The specimen strength increases with the increase of curing age,but the increase rate decreases gradually,In general,the effect of adding waste concrete particles with the particle size of 0-2.36 mm is better than that of adding particles with the particle size of 2.36-4.75 mm.(2)Under different curing ages(7d,14 d,28d,and 49d),the change law of the stress-strain curve is similar,but with the increase of curing age,the peak state of the stress-strain curve changes from flat to the peak.The stress-strain relationship curve can be expressed by a unified functional relationship.Gaussamp function can well fit the stress-strain curve relationship of waste concrete granular material cement solidified sludge.The ultimate strain of the specimen is stable in a fixed range,and the ratio of deformation modulus to unconfined compressive strength is 39-96.(3)The shear strength of the sample increases with the increase of normal stress(50k Pa,100 k Pa,150 k Pa,and 200 k Pa),with the increase of curing age(7d,14 d,28d,and49d),and with the addition of waste concrete particles.The cohesion of the sample increases with the increase of curing age,the internal friction angle of the sample is generally stable in a fixed range,the moisture content of the sample decreases with the increase of curing age,and the shear stress reaches the peak after the shear displacement of2.5mm.(4)The mixed soil is made of waste concrete particles and cement solidified sludge.Compared with the traditional cement solidified sludge,the mechanical properties have been improved to a certain extent,which shows that it is feasible to treat the thickened sludge with waste concrete particles and cement,which has a certain reference significance for the recycling of resources.