Research On The Stability Of Foamed Concrete

In recent years,foamed concrete has been increasingly used.But slurry instability often occurs during its use,such as sedimentation and collapse;In addition,understanding in regard to the stability of foamed concrete is also not consistent.The purpose of this paper is to discuss the concept and description of the stability of foamed concrete,analyze the main factors affecting the stability,and prepare foamed concrete with good stability.In this paper,the concept of stability is clarified from the hardening of foamed concrete.It is concluded that the stability of foamed concrete is as follows: after the hardening of foamed concrete,it has a small,uniform and closed pore structure on the vertical and the pouring surface has no or less settlement.The condition of fresh concrete and the structure of hardened foamed concrete can reflect the stability,and it puts forward the quantitative indicater system of stability of foamed concrete,namely,the settlement rate of foamed concrete,dynamic volume water absorption ratio,average aperture ratio,circularity distribution and so on.Based on work above,the effects of foaming agent concentration,water-cement ratio,polycarboxylate superplasticizer and HPMC on the stability of foamed concrete are studied.The corresponding parameters are measured and analyzed to find the law of concrete stability.The results show that sedimentation rate,dynamic volume water absorption ratio,average pore size ratio and so on are used to indicate the stability which is appropriate.At the same time,the regularity of the influence of these factors on the stability is obtained.With the increase of the dilution concentration of foaming agent,the increase of the water-cement ratio,the increase of the amount of polycarboxylate superplasticizer and the increase of the content of HPMC,the stability of foamed concrete shows the effect of increasing first and lower later,and the stability of foamed concrete has one best value.According to the optimal value of each factor,that is,the foaming agent diluted 30 times,the water-cement ratio 0.45,the polycarboxylate superplasticizer and HPMC 0.03% of the cement mass,to prepare foamed concrete with dry density of 500 kg / m3,the physical and mechanical properties of it are excellent,including mobility of 180 mm,dry density of 514 kg / m3,28 days compressive strength of 2.3MPa,thermal conductivity of 0.118 W /(m.K).Along with settling rate of the foamed concrete 1.5%,the ratio of average aperture 1.02 and the upper average pore diameter 150?m,the stability is good.