Research On The Air-void System Characterization And Regulation And Properties Of Foamed Concrete

Light foamed concrete(LFC) is a new kind of building material with simplepreparation procession, good workability, excellent heat insulation performance andhigh energy absorption property, which suits for important engineering constructionsuch as side wall heat insulation system and aircraft arresting system. This materialmeets the requirements of energy saving and environmental protection and has boardapplication prospects, but it also has some problems such as low strength, poordurability and stability. In the paper foam stability, slurry property, air-void systemcharacterization method, mechanical property, water absorption and transportationand practical applications of LFC were studied, the relation among the composition,pore-structure and macroscopic performance of LFC has been discussed which issignificant to develop the theory and guide the application of LFC. The main researchwork and conclusions of the paper are:The variation trend of foam films and foam diameter in form process, stablephase and break stage is analyzed by optical microscope and measuring software, themethod to control the drainage and expand rates of foam by regulating the foam watercontent is proposed, the relation between foam stability and foam water content isbuilt and the optimal foam coefficient is obtained.The air-void system of LFC is researched by image processing and statistics:Basic parameters such as porosity, air-void diameter, shape factor and air-voidfrequency are quantitative characterized, the new concept named “sapcing factor” isalso calculated. Air-void parameters of different mixes are achieved, the effect law ofcomposition on air-void system is studied systematic and correlation among air-voidparameters is discovered, to provide theoretical basis of obtaining air-voids withsmall size, regular shape and uniform distribution.Fresh properties of LFC is measured by fluidity and stability, the influencingfactor is studied to direct the designation and preparation of LFC with goodworkability. Water absorption and sorptivity which based on unsaturated flow areused, to analysis the moisture absorption and movement behavior, durabilityevaluation method of LFC that using in unsaturated environment is built. The relationbetween water absorption and air-void system is analyzed, and the effects of matrix defect, porosity and air-voids size on water transmit are studied, basing on the aboveworks the model of water migration which contains driving force and path is madeclear. Comparing the absorption measured by vacuum saturation and immersionmethod, and through the SEM analysis of air-void wall, the model of waterabsorption in unsaturated environment is built which gives an guide to durabilitydesignation of LFC.The influences on mechanical property of LFC are analyzed deeply, the optimalstrength-porosity model is acquired, which sets an important basis for the mixturedesignation of LFC. The engineering verify experiments of LFC which dry densityranges from400to600Kg/m3are carried out, and the results show that the materialshave good workability, high stability and combined well with plasterboard, which canmeet the requirement of engineering applications.