Study On Basic Mechanical Properties Of Rubber Concrete And Its Damage Mechanism Under Salt Corrosion And Impact Load

As a new type of composite material,rubber concrete is widely used in airfield runways,roads,dams,bridges and other engineering structure.During its service,rubber concrete is subjected to rolling crushing of the vehicle,the washing of rapids and sediments,impact and abrasion of sand particles and media Corrosion seriously affects its durability and safety.In this paper,the basic mechanical properties of rubber concrete as well as the dynamic shock damage,corrosion damage and mechanical behavior of rubber concrete by using automatic impact ball pressure gauge were studied.The damage morphology and mechanism characteristics were analyzed by laser confocal microscopy(LSCM),scanning electron microscopy(SEM),X-ray and diffractometer(XRD).Rubber concrete by small energy impact and corrosion damage provide a theoretical basis.This work were supported by Chinese National Natural Science Foundation(Grant No.11162011,No.51468049 and No.11662012)Details researches are as follows.1.The cube compressive strength,axial compressive strength,flexural strength,axial compressive strength under different particle sizes of rubber concrete were studied.(particle size: 10 mesh,40 mesh,80 mesh;content of 10% Stress-strain curve,elastic modulus,Poisson ’s ratio).2.The impact damage properties of rubber concrete and reference concrete with 10% particle size(10 mesh,40 mesh,80 mesh)were studied by using automatic impact ball pressure gauge.The results show that the addition of rubber improves the dynamic hardness and recovery coefficient of concrete.With the decrease of the rubber particle size,the dynamic hardness value and the recovery coefficient increase,while the damage degree decreases.With the increasing of the impact load,ordinary concrete has the first load yield and the yield load is less than the rubber concrete,the yield load of rubber concrete with a particle size of 80 mesh is the maximum and has a good resistance impact;Under the action of impact load,the material elastically deforms to form a spherical crowded pits,and the indentation edges show different degrees of extrusion forming material accumulation,The 80 mesh rubber is more evenly distributed in the concrete,and the damage zone is more stable and continuous without obvious micro cracks.3.By using Taguchi method,the damage test of rubber concrete under salt co rrosion and impact load was designed.The degradation rules of rubber concrete with different particle sizes and different dosages were studied under corrosion time.Research result:(1)The indentation size of rubber concrete is the smallest when t he height of impact is 23 cm,the diameter of rubber is 40 mesh,the content of r ubber is 10%,the number of Immersion Corrosion of rubber concrete is 30 d,the indentation of rubber concrete with particle size of 40 mesh,is 10% The small est size.The main factor that affects the indentation size is the impact height con tribution rate of 99.27%,which is the corrosion time contribution rate of 0.436%,the rubber content contribution rate of 0.235%,the smallest impact for the rubbe r particle size contribution rate is attains 0.058%.(2)With the increase of soakin g time,the same gradual change rule of mass and compressive strength:first incre ases and then decreases,reaching the maximum at 60 days,and decay of mass a nd compressive strength occurs at 90 days;(3)The dynamic change of hardness and recovery coefficient of the material at different times(0d,30 d,60d and 90d)showed the same gradual change rule.The mechanical properties of the surface decreased with the increase of corrosion time,It was the lowest in 60 days,and slowly rose in 90 days.4.Microscopic analysis of morphology and variation of chemical composition in corrosion process.Research result:(1)By analyzing the indentation morphology of impact ball pressure surface under the corrosion of sodium sulfate solution,th e indentation damage firstly decreases and then increases with the increase of corr osion time,and then decreases slightly at 30 days,then At 90 days,the degree o f serious increase.The initial products of corrosion fill the microcavity and micro crack of rubber concrete,which can resist the impact load.However,as the produ ct of corrosion gradually increases,the formation of expansion stress aggravates th e formation of defects,resulting in the deterioration of materials and the increase of damage.(2)The morphology and XRD of rubber concrete were analyzed by s canning electron microscopy and X-ray under different corrosion time,it shows tha t ettringite and gypsum are filled in the gaps of rubber concrete,interface transiti on zone and surface-to-surface impact in the immersion of sodium sulfate solutionLoad has a certain resistance.