Performance Degradation Regularity Experiment Research On Coal Gangue Aggregate Concrete

Sulfate attack of concrete occurs frequently in underground structures,hydraulic structures and coastal construction areas,results in the structure salting out,dropping out even loosing,scattering,the durability of concrete reducing,which do great damage to the structure.In this paper,the orthogonal tests of four factors and three levels are carried out with Na2SO4 solution concentration,fly ash mass concentration,coal gangue mass concentration and water cement ratio as experimental factors,study on the performance degradation rule and mechanism of concrete against sulfate attack in two kinds of environment,one long-term immersion and the other dry-wet cycling,and the following conclusions are drawn:?1?The damage process of concrete in the solution is divided into two stages,during the initial stage:the pores of concrete is filled with erosion products,and compact the structure,the mass,the compressive strength,the dynamic modulus and the flexural strength of concrete are increased;during the late stage:the expansion material still continues to produce,the crystallization pressure exceeds the concrete tensile strength,causing the crack producing and aggregate falling off from the edge of concrete,each index dropping from the high position.?2?In the cases of dry-wet cycling,the apparent damage of blocks are more obviously than that in the long-term immersion group,indicating that the dry-wet cycling is more significant to the deterioration of the block,meanwhile,the high concentration solution benefits to the index reaching the peak in the initial stage,but in the later stage,the high concentration solution do more damage to each index.?3?Among the influential factors on the mass change ratio,corrosion resistance coefficient of compressive strength and relative dynamic modulus,solution concentration and water binder ratio are dominant factors;however,adding appropriate coal gangue and fly ash contributes to inhibiting the deterioration of concrete performance.?4?Based on the basic decay equation of concrete,taking water binder ratio,coal gangue mass concentration,fly ash mass concentration and Na2SO4 solution concentration as the action factors,the relative dynamic modulus of elasticity,the rate of mass change and the corrosion coefficient resistance of compressive strength as criterion,put forwards a prediction model of concrete four index damage life.?5?According to the rules of two-dimensional Von cellular neighbors,establishes two dimensional cellular automaton model to simulate the process of SO₄^2-transmission in concrete,predicts different ages of concrete sulfate attack,results show that the established two dimensional cellular automaton model is reasonable,in addition,analysis the advantages.