Application Of Recycled Powder In Medium Strength Concrete

Recycled powder is the waste powder recycled from asphalt mixing plant,which has a large amount of recovery,high treatment cost,harm to human health and pollute the environment.In order to expand the utilization of recycled powder in engineering,it is applied to concrete to reduce the harm of recycled powder to the surrounding environment and reduce the floor area.Therefore,this paper first analyzes the basic properties of recycled powder,analyzes the micro morphology and mineral composition of recycled powder by SEM and XRD,and finally adds recycled powder into mortar and concrete to analyze the influence of recycled powder content on mortar and concrete performance.The research contents and results are as follows:(1)The basic properties of recycled powder and cement were tested,and the differences of particle size distribution and micro morphology of recycled powder and cement were analyzed.It was found that the recycled powder was less than 10 μ The particle number of M is larger than that of cement;The recycled powder particles are gathered in the form of clusters,and the cement particles are gathered in the form of particles;The water demand of recycled powder is greater than that of cement.(2)It is found that the fluidity decreases with the increase of recycled powder content.When the dosage is less than 15%,the recycled powder has no obvious effect on the workability and strength of the mortar;When the content of recycled powder is more than 15%,the workability and strength of recycled powder mortar decrease.(3)The effect of recycled powder on the workability and mechanical properties of concrete was studied.It was found that recycled powder had a negative effect on the workability and mechanical properties of concrete.When the content of the mixture is 10%,the effect of recycled powder on the workability and mechanical properties is the least,and the water retention and cohesion of the concrete can be improved,and the loss of the slump is less than that of the reference concrete;When the content of the powder is more than 20%,the recovery powder has obvious influence on the working and mechanical properties.(4)by means of microscopic test,it is found that 100 D can produce large amount of ettringite,which will affect the uniform distribution of the gel,resulting in a large number of pores in the internal structure.XRD results show that the recovery powder has no obvious effect on the hydration product components of concrete cement,and mainly plays the role of filling pores;The results of NMR show that when the amount of recycled powder is 10%,the porosity of concrete can be improved and the number of large pores can be reduced.(5)The frost resistance,drying shrinkage and chloride ion penetration resistance of recycled powder concrete are studied.It is found that only the mass loss rate and strength loss rate of reference concrete and 10% recycled powder concrete are within the range of specification requirements after 150 freeze-thaw cycles;The chloride penetration resistance of recycled powder concrete reaches grade Q-ii;The shrinkage value of recycled powder concrete is larger than that of ordinary concrete,and with the increase of age,the shrinkage value increases continuously.The longer the time,the shrinkage value of concrete increases slowly and tends to a stable value.When the recycled powder content is more than 10%,the shrinkage value of concrete will be greatly increased.(6)Through the benefit analysis of recycled powder,it is found that the cost of using recycled powder in C30 concrete can be saved by 12000 yuan,the treatment cost of recycled powder can be saved by 2202 yuan,and great environmental and social benefits can be brought.