Experimental Study And Application Of Foam Concrete Based On Freeze-thaw Cycles

In order to solve the shortcomings of conventional foam concrete in tunnel application in cold regions with complex strata,the filling materials of tunnels in complex strata should be equipped with cold insulation,thermal insulation,seismic and optimization support.The purpose of this paper is to study the mechanical properties of foam concrete mixed with various admixtures.First of all,in order to study the influence of low temperature environment on the strength of foam concrete,the compressive strength of foam concrete is studied under different mixture ratios.In this paper,25 freeze-thaw cycles are used to prepare a high strength cold proof and thermal insulation foamed concrete by adding different lengths of fibers and water reducing admixtures.Through cross comparison test,the results show that when the water cement ratio is 0.5,when 19mm polypropylene fiber and polycarboxylate superplasticizer were added,the compressive strength of foam concrete was 427%higher than that of the foam concrete without adding fiber and water reducer.After the freeze-thaw cycle,the strength loss was lowest and the minimun loss rate was 4.4%.At the same time,the thermal conductivity of foam concrete is tested under this mix ratio.It is found that the thermal conductivity of concrete specimens only doped with fiber is the lowest.Finally,the SEM scanning technology is used to scan the internal structure of the cracked concrete,and the microstructure of the concrete is analyzed comprehensively,and the frost thawing characteristics of the foam concrete are analyzed.Through microscopic analysis,it can be found that the internal structure of concrete has been damaged to varying degrees after freeze-thaw cycles.After adding fiber and polycarboxylic acid superplasticizer,the internal integrity of concrete is very good,the connection between cement is more compact,and cracks are reduced.Figure 39 Chart 15 reference 65...