Research And Application Of Ceramsite Lightweight Concrete Wall Material

As a non-load bearing component,ceramsite foam concrete inner partition board is widely employed in high-rise and civil residential buildings owing to its light weight,heat insulation,sound insulation and noise prevention,flame retardance and earthquake resistance.However,there exsit still many problems in practical engineering applications of ceramsite foam concrete,such as its high density and high risk of shrinkage and cracking,greatly limitting its popularization and application in construction engineering.Civen the above problems,the single factor variable method was first used to systematically study the matrix ratio of ceramsite concrete,and the influences of the ceramsite pre-wetting system,water-binder ratio,volume sand ratio,ceramic sand content and fly ash content on the compressive strength,apparent dry density and drying shrinkage of ceramsite concrete matrix were investigated.Then,ceramsite foam concrete with a density grade of 1100 was prepared based on the optimized matrix mix ratio and the designed target wet density of concrete,and the effects of foaming agent type,foam content and polypropylene fiber content on the compressive strength,apparent dry density,volume water absorption and drying shrinkage were investigated.After that,combining with the practical engineering application,the influences of volume sand ratio,ceramic sand content and fine aggregate types on the compressive strength,apparent dry density,volume water absorption,thermal conductivity and drying shrinkage of 1200-grade ceramsite foam concrete were investigated.Finally,X-ray computed tomography(X-CT)was used to analyze the pore structure of ceramsite foam concrete,and the relationship between pore structure parameters,compressive strength and thermal conductivity was established,which provides technical basis for the production and practical engineering application of ceramsite foam concrete inner partition board.The main results and conclusions are as follows:1.The ceramsite is easier to reach the saturated surface dry state when pre-wetting time is up to72 hours,and the fluidity of ceramsite concrete increases with increasing pre-wetting time;and the workability of ceramsite concrete with volume sand ratios varying 40%～45%are the best;additionally,the 28d compressive strength of ceramsite concrete with water binder ratio between 0.28and 0.31 exceeds 15 MPa;when the content of ceramic sand exceeds 40%,more pores will be introduced,leading to the reduced homogeneity of ceramsite concrete;when the content of fly ash is10%,the decreased drying shrinkage of ceramsite concrete was obtained.2.The foam prepared using dodecyl sulfonate foaming agent has the best stability with a bleeding rate of 115 m L for 1 h,and the volume water absorption rate of ceramsite foam concrete prepared using this foaming agent is the lowest of 12.4%in 48h.The 28d drying shrinkage of ceramsite foam concrete with 10%foam content is the lowest of 0.381 mm/m;in addition,the increase of polypropylene fiber content has an insignificant effect on the compressive strength of ceramsite foam concrete,but it can effectively reduce the drying shrinkage of ceramsite foam concrete.The 28d compressive strength of 1200-grade ceramsite foam concrete with a water ratio of 0.26 is between 11MPa and 15 MPa,among which the 28d apparent dry density and compressive strength of ceramsite foam concrete with 10%ceramic sand are 1250 kg/m~3 but can achieve 14.4 MPa,meetting the strength and density requirements specified in JC/T 2214-2014“Reinforced ceramsite concrete lightweight wallboard”.The drying shrinkage of ceramsite foam concrete mixed with 3‰UEA expansion agent in 28d and 90d is 0.303 mm/m and 0.365 mm/m,respectively,which is 19.3%and13.1%lower than that of the reference group,conforming to the drying shrinkage requirements specified in JC/T 2214-2014“Reinforced ceramsite concrete lightweight wallboard”.3.The porosity of ceramsite foamed concrete is mainly controlled by the connected pores in aggregate,and the total porosity of ceramsite foamed concrete will be increased by increasing the content of foam and pottery sand.Adding 10%ceramic sand can effectively reduce the porosity of ceramsite foam concrete matrix,optimize the pore diameter and improve the pore shape factor;the compressive strength of ceramsite foam concrete is affected by both porosity and pore size distribution.When the total porosity is the same,the smaller the median aperture(D50)value is,the higher the compressive strength of ceramsite foam concrete is.The thermal conductivity is greatly impacted by the porosity,the porosity increases from 20%to 25%,and the thermal conductivity of ceramsite foam concrete decreases from 0.20326 W/(m·K)to 0.18231 W/(m·K).