| Foam concrete has been widely used in the construction field at home and abroad because of its light environmental protection,sound insulation and seismic resistance.In recent years,it has been gradually found that foam concrete will produce large deformation and absorb foreign energy when it is impacted,which has a certain buffer effect Therefore,this material is also widely used in the construction of traffic protection facilities.A large number of research data show that people’s understanding of foam concrete is only used as wall insulation,sound insulation,for the impact of foam concrete mechanical properties are relatively scarce.How to improve the impact resistance of foam concrete is studied by few scholars.In this paper,a kind of foam concrete with perfect mechanical properties and easy molding was prepared by using mechanical stirring as the foaming method and sodium dodecyl sulfate(needle shape)as a foaming agent.In the process of preparation,the proper amount of rubber powder is added to improve the dynamic buffer energy consumption of foam concrete,so that it can be better used in traffic protection facilities.After perfecting the preparation scheme,the static,dynamic and microscopic SEM experiments were carried out,and the following conclusions were obtained;(1)Water-cement ratio has the most significant effect on the compressive strength of foam concrete,When the ratio of water to cement is 0.35,the ratio of fly ash to cement is 5:1,the content of water reducing agent is 1.04%,and the content of accelerator is 4%,The performance of foam concrete is the best.d static compressive strength of 7 and 28 Mpa.8.04 and 10.23 respectively When the water-cement ratio is less than or greater than 0.35,The strength of foam concrete has decreased obviously.(2)Adding water reducing agent to the preparation of foam concrete can improve the fluidity of the mixture and promote the uniform dispersion of bubbles in concrete.Adding a proper amount of accelerator can shorten the hardening time of the material and effectively avoid the phenomenon of mold collapse in the process of forming.(3)The compressive strength of foam concrete decreases with the increase of rubber content,and when the rubber content is 5%-7.5%,the strength decreases greatly.When the water absorption is increased from 0%to 10%,the volume water absorption decreases and the mass water absorption increases.(4)The dynamic uniaxial compression experiments of 0～10%foam concrete with rubber content MPa 0.2 and 0.4 are carried out.According to the stress-strain curve,the whole process can be divided into three stages:linear elasticity,plastic yield and complete failure.When the content of rubber powder is certain,the dynamic compressive strength will be improved when the impact pressure is increased.(5)the pressure is fixed,compared with the reference foam concrete specimen,the broken degree of the specimen with rubber powder is also greater,and the relative energy absorption effect is better.And the degree of fragmentation increases with the increase of air pressure.(6)When the impact pressure is fixed,the amount of rubber is increased continuously,and the dynamic strength of foam concrete is strengthened first and then weakened.When the rubber content is 2.5,the maximum strength of the specimen is slightly higher than that of the reference specimen.However,when the content is greater than 5,the dynamic strength decreases greatly.When the rubber content increases to 10,the corresponding strength is much smaller than that of the reference specimen,and even can only reach 30%of the original strength.(7)After microscopic observation,it is found that many pores in foam concrete have a good energy absorption effect.The interface transition zone between rubber particles and cement materials is formed,the two materials can not be effectively combined,and the cracks after dynamic load are mostly formed here.When the material is subjected to static compression experiments,the strength decreases with the addition of rubber,while in dynamic impact experiments,the degree of breakage is more severe.Figure[57]table[7]references[67]... |
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