Research On The Strength And Deformation Features Of Subgrade Material Of Construction Waste

With the deepening of the urbanization process, a large amount of construction produced much construction waste, the ecological environment has been seriously pollutioning, we need to find an effective solution.Recycling construction waste will effectively solve a variety of problems such as stacked of the construction waste and environmental pollution, which will be the future development trend of industry.Therefore, researching on recycling the construction waste has important and far-reaching significance in the development of circular economy.An important direction of recycling construction waste is road engineering. Highway construction in our country is in a high-speed development period, the material performance requirements of the road embankment is not high, the use of construction waste in road engineering can greatly reduce the consumption of natural sand and soil in the process of construction, also meet the construction waste to maximize the utilization of renewable resources.In the developed countries,the resource utilization of construction waste degree is quite high, developed countries usually recycled construction waste in the form of recycled aggregates,68% of the recycled aggregates used in road engineering and building foundation.The resource utilization of construction waste degree is very low at home.In Guangzhou,the resource utilization of construction waste is in initial stage at present.In this paper, depending on new town of Guangzhou iron and steel group and metro line 14 project engineering, construction waste as the main object of study, with cement, lime, fly ash or slag powder for stability, through a large number of laboratory tests and numerical simulation,this paper researches on the strength and deformation characteristics of the subgrade filling with construction waste from the unconfined compressive strength、water stability、shrinkage deformation and subsidence deformation characteristics. The main results were as follows:1. Under the condition of naturally dry,research on the composition and the basic characteristic of the construction waste, the results show that:bibulous rate of coarse material is ωx=13.7%, table dry density of coarse material is ρ=2.14g/cm3; liquid limit of fine material is ωL=33.5%; plastic limit of fine material is ωP=24.5%, plastic index is Ip=ωL-ωP=9。Kw=5/5 of the construction waste mixture grading curve is flat, show gradation of mixture is good.2. Unconfined compressive strength of subgrade filling with material increased gradually with the increase of the inorganic binder content. When dosage and proportion is same,cement、lime and slag powder increase in strength of subgrade mixture were obviously higher than lime fly ash. The proportion of cement and fly ash、lime and fly ash、lime and slag powder in subgrade mixture is 1:2 better than 1:3. Mixed with fly ash In the construction waste subgrade mixture stabilized by cement obviously improve the strength of mixture. Mixed with cement can effectively improve the early strength of the mixture.3. The water stability of cement stabilized subgrade filling with construction waste mixture is good, the water stability of lime and fly ash、lime and slag powder stabilized subgrade filling with construction waste mixture is relatively bad. When dosage and proportion is same, the water stability of lime and slag powder stabilized subgrade filling with construction waste mixture is better than lime and fly ash stabilized subgrade filling with construction waste mixture.4. Cement has bigger influence on drying shrinkage coefficient of mixture than lime and fly ash、lime and slag powder,lime and fly ash influenced on drying shrinkage coefficient of mixture is similar to lime and slag powder. Cement influenced on drying shrinkage strain of mixture is very bigger than lime and fly ash、lime and slag powder, lime and fly ash influenced on drying shrinkage strain of mixture is little bigger than lime and slag powder. Lime and fly ash influenced on rate of water loss of mixture is similar to lime and slag powder,lime and fly ash、lime and slag powder is bigger influence on rate of water loss of mixture than cement.5. Combined with project example, this paper simulation analysis subgrade which filled with construction waste deformation characteristics by finite element software, it is concluded that the settlement change rule of subgrade consistent with the actual engineering. It is knowed that the subgrade which filled with construction waste mixture has good carrying capacity by the unconfined compressive strength test、water stability test and shrinkage test.Deformation characteristics which caused by filling subgrade with construction waste and general clay are almost same, construction waste is a kind of good subgrade filling material.