Study On Properties Of Foam Concrete For Airport Road Foundation In Permafrost Regions

There are a lot of permafrost environment in China,which has high economic development and utilization value.At present,the development and construction of airports in permafrost regions in China is in the initial stage,and there is a lack of relevant experience and technology.With the increase of global temperature,the environmental degradation in permafrost regions is becoming more and more serious.In order to deal with a series of diseases caused by the degradation of frozen ground in airport runway,and to maintain the stability of frozen soil layer and runway and improve the service life of the airport,based on the requirements of the airport’s thermal insulation performance and strength performance of the runway in permafrost regions,this paper attempts to develop a reinforced foam concrete pavement base material with high thermal insulation performance and mechanical properties.The specific research is as follows（1）according to the basic performance requirements of airport runway base,by analyzing the parameters of compressive strength,flexural strength and thermal conductivity,the mix proportion of foam concrete is optimized.It is concluded that when the water cement ratio is 0.5 and the dry density is 1200kg·m^-3,the foam concrete with 30%fly ash and 0.15%6mm glass fiber is the best comprehensive performance.On the basis of meeting the strength performance requirements of ordinary civil airport runway base,its heat insulation performance is far stronger than that of ordinary base material.（2）optimizing the reinforced concrete process and maintenance scheme of foamed concrete.The conclusion is that when the diameter of the steel bar is 8mm,the spacing between the reinforcing bars is 20cm,and the bottom of the bar net is 1.5cm,the strength of the foam concrete specimen is improved by the reinforcement process,and the 28d compressive strength and flexural strength increase by 19.27%and 34.3%respectively.At the same time,through indoor simulation test,it is concluded that low humidity and large temperature difference maintenance environment will cause permanent deterioration to the strength and thermal insulation properties of foam concrete,while maintaining relatively stable relative humidity and temperature during construction maintenance.（3）freezing and thawing cycle tests were carried out to test the frost resistance of foamed concrete.Meanwhile,Wiener process simulation was used to predict the service life of the specimens.It was concluded that after 150 times of freeze-thaw cycles,the mass loss rate of the specimens was small,and the service performance could still be maintained.