Application Research Of Waste Rubber And Recycled Brick And Concrete Aggregate On Sidewalk Surface

Waste concrete and waste brick is the main component of recycled aggregate in China.From the content of them,the brick content is about 30%to 50%,and the concrete content is 40%to 60%.Due to the defects of high water absorption rate and low strength of recycled brick and concrete aggregate,its application in the field of civil engineering is greatly limited.Rubber has good elasticity properties.Incorporating rubber particle into concrete or mortar can improve its wear resistance,improve its toughness,shrinkage and freeze resistance.Therefore,the research of synergistic treatment and resource utilization of waste rubber particles and recycled brick aggregate has certain innovationRecycling of recycled brick-concrete fine aggregate and waste rubber particles as pavement surface material is studied in this paper.Firstly,the basic properties of the test materials such as water absorption,apparent density,crushing index and particle grading were tested.Then the recycled aggregate are replaced by different proportions of rubber particles with equal volumes to prepare all recycled mortars with different water-cement ratios,and tested for workability,strength,shrinkage,impermeability and frost resistance.Through the hydrophilicity test of rubber particles and recycled aggregates,the apparent morphology of rubber particles was observed by scanning electron microscope,and combined with the failure morphology of all recycled mortar,the mechanism of the effect of rubber particles on the technical properties of fully regenerated mortar was analyzed,Finally,the mathematical model of the compressive strength of all recycled mortar with rubber particles is established.The main research results and conclusions are as follows:(1)Basic performance of recycled brick fine aggregate and rubber particles.The apparent density and crushing index of recycled brick-concrete aggregate are both smaller than of natural aggregates,and the water absorption rate is relatively high.When rubber particles are mixed into the recycled aggregate,the crushing index of the recycled aggregate gradually decreases with the increase of the rubber content.When the rubber content is 3%-30%,the recycled aggregate gradually transfers from fine sand to medium sand(2)Technical performance of all recycled mortar with rubber particles.The workability of all recycled mortar decreases with the decrease of water-cement ratio and increases with the increase of rubber content.The smaller the water-cement ratio,the greater the apparent density and strength of the all recycled mortar,and the more obvious its brittle failure characteristics.When the increase of the rubber content,the apparent density and strength of the mortar increase first and then decrease,and the characteristics of toughness failure gradually become obvious.The smaller the water-cement ratio,the smaller the shrinkage of the all recycled mortar,the better the impermeability and frost resistance,and the incorporation of rubber particles improves the durability of the fully reclaimed mortar.It is found that when the content of rubber particles is 5%and the water-cement ratio is 0.8,the all recycled mortar meets the requirements of square tiles.(3)The analysis of the mechanism of rubber particles on the technical properties of all recycled mortar.The hydrophobicity of the rubber particles gives it a ball effect,and the uneven surface produces an air entrainment.The ball effect and air entrainment effect of the rubber particles cause the fluidity of the all recycled mortar to increases,and its hydrophobicity reduces the water retention of mortar.The ability of elastic deformation of the rubber particles has a strengthening effect on the strength of the mortar,which its hydrophobicity and air-entraining effect have a weakening effect on the strength,therefore,there is a suitable amount of rubber particles to improve the strength of the mortar.The hydrophobicity and air-entraining effect of the rubber particles increased the water penetration resistance and improved the mortar's impermeability.The elastic deformation and air entrainment of the rubber particles can eliminate the internal stress which is caused by the icy expansion of pore water to a certain extent,and have a significant improvement effect on the frost resistance of the mortar.(4)According to the research results at home and abroad,the regression rate of the compressive strength change rate of natural mortar mixed with different proportions of recycled aggregates and rubber particles was regressed.Combined the experimental results.a mathematical model of the relationship between the amount of waste rubber content and the compressive strength of all recycled mortar is established to predict the compressive strength of all recycled mortar with rubber particles.