Research On The Structure, Properties And Microstructure Of Foamed Concrete

The correlation between composition and mechanical properties, thermal propertiesand pores structure of foamed concrete below600kg/m3is researched in this papersystematically in order to provide the basis for the design and application of foamedconcrete.The research shows that the foaming agent type and foaming agent concentrationhave obvious influence on pores structure and compressive strength. Most of the poressize of the foamed concrete prepared by three kinds of foaming agentconcentrates within400μm, but the pores size distribution is different. Foaming agentconcentration has obvious influence on pores morphologies. The foaming agentconcentration too high can lead to more connecting pores, larger pores deformationand low strength of foamed concrete. With the foaming agent concentration reducing,the pores morphologies can be improved and strength of foamed concrete increasesgradually. The foaming agent concentration too low can reduce foam stabilityobviously. So there is a suitable scope about foaming agent concentration. The foamedconcrete with the same density level with smaller ratio of pores within100μm, lagerratio of pores within100μm-400μm, smaller ratio of pores larger than400μm, andsmaller roundness possesses higher strength.The water-binder ratio has obvious influence on pores structure and compressivestrength of foamed concrete. With water-binder ratio increasing, the ratio of poreswithin100μm decreases gradually, and the ratio of pores within100μm-200μmincreases. With water-binder ratio increasing, pores roundness presents a decreasingtrend, that is, pores deformation reduces. The compressive strength of foamedconcrete increases first and then decreases. The water-binder ratio should be choseboth considering the stability of casting slurry and mechanical properties of foamedconcrete.There is good correlation between the density and the compressive strength and thethermal conductivity of foamed concrete. The correlation coefficient is0.9708and0.9725respectively. With density reducing, the average pores size increases gradually.There is good correlation between the density and the porosity with the correlationcoefficient0.8972.Polymer emulsion can effectively improve the shrinkage properties and poresstructure of foamed concrete. The research shows that after adding the polymer emulsion, the ratio of pores within100μm decreases gradually and the ratio of poreswithin100μm~200μm and lager than400μm increases, the average pores sizepresents an increasing trend. The more the polymer emulsion and the longer the age,the lager the shrinkage decline amplitude is. When EVA emulsion is6.0%,3dshrinkage decline by10.87%only, but56d shrinkage decline by54.02%.