Experimental Study On Effect Of Rubber Powder Content On Concrete Frost Resistance

Many concrete projects in our country are located in the cold regions.These concrete structures are being destroyed by freeze-thaw cycle.In order to solve the problem of freeze-thaw resistance,a great deal of research has been done,including adding rubber powder to concrete.In cement concrete,rubber powder can play the role of"solid aerosol",improve the inner pore structure of concrete.Appropriate amount of rubber powder can not only improve freeze-thaw resistance,but also solve the problem of recycling of waste rubber.It has many meanings such as resource recycling and environmental protection.Through experiment,the relationship between the mechanical properties of rubber concrete specimens and the amount of rubber powder was analyzed.This paper studies the failure process under load and the propagation characteristics of stress wave of rubber concrete by using the technique of shock elastic wave nondestructive test.Provide economical and convenient means for engineering inspection.The main achievements of this paper are:(1)It can be seen from the micrograph of the concrete inside the concrete photographed by SEM electron microscope that the incorporation of proper amount of rubber powder can improve the structure of fine cracks in the concrete,thereby delaying the destruction of the structure and improving the frost resistance of the concrete.(2)With the increase of freeze-thaw cycles,ordinary concrete specimen and the quality of mixing rubber powder concrete has a trend of first increased after decreased,after freeze-thaw cycles,the quality of the mixing amount of rubber powder concrete loss rate is lower than normal concrete,when the rubber powder content of 15 to 25kg/m~3,mass loss minimum.(3)Rubber powder reduces the strength of concrete.As the number of freeze-thaw cycles increases,the strength of ordinary concrete and rubber powder concrete first increases and then decreases.The loss rate of strength of rubber powder concrete is lower than that of ordinary concrete.When rubber powder is mixed with 15-20 kg/m~3,the strength loss rate is lowest.(4)Under the freeze-thaw cycle,the velocity of ordinary concrete decreases,and the wave velocity of rubber powder concrete Increase and decrease with numbers of freezing-thawing cycles.When the freeze-thaw cycle is large,the wave velocity loss rate of rubber powder concrete is lower than that of ordinary concrete.(5)There is a good correlation between the wave velocity and strength of concrete,and the correlation coefficient is above 0.9 by using quadratic function.Therefore,the wave velocity and strength can be measured by means of shock elastic wave NDT.At the later period of freeze-thaw,the wave velocity decreases with the increase of freeze-thaw cycle,which shows that the remaining life of concrete can be predicted by detecting the wave velocity.