Preparation And Properties Of Aerogel Foamed Concrete

Technological innovation of building materials and improving the energy efficiency of building envelope materials are effective means of energy saving and emission reduction.Foam concrete is a common building energy-saving thermal insulation material,but ordinary foam concrete has large bulk density,high thermal conductivity,and poor thermal insulation ability.Aerogel is a new type of nanoporous solid material with high porosity,low density and low thermal conductivity（≤0.018w/（m k））.With the emergence of technology,the preparation cost of aerogel is getting lower and lower,and it is expected to become a building material with excellent thermal insulation ability.This study was commissioned by a company to prepare aerogel foam concrete and study its properties.Firstly,the effects of aerogel content and foam content on the performance of foamed concrete were explored using animal protein as foaming agent.Secondly,aerogel foamed concrete（AGFC）was prepared with hydrogen peroxide as foaming agent（HP）,and the effects of aerogel content,temperature and fly ash content on foaming performance and physical and mechanical properties of aerogel hydrogen peroxide foamed concrete were analyzed.impact,the results show that:（1）When the amount of aerogel is small,the fine aerogel powder can make the cell walls of the foam concrete more dense.When the amount of aerogel is large,its light and hydrophobic properties make it impossible for the cement paste to fully absorb it.Wrapped and cured will produce more structural defects in the specimen.Therefore,the performance of precast foam concrete is better when the aerogel content is 1 wt%.（2）With the increase of the foam content,the density of the aerogel foam concrete drops from 900kg/m~3to 300kg/m~3,the compressive strength drops from 4.8MPa to 0.43MPa,and the thermal conductivity drops from 0.1921w/（m·k）decreased to 0.06984w/（m·k）,and the water absorption rate decreased from 9.3%to 48.8%.When the foam content is small,the aerogel can fill the tiny gaps in the pore wall of the specimen,which can increase the strength of the specimen after standard curing for 28 days by 11.6%;when the foam content is high,too little slurry cannot accommodate the hydrophobic aerogel powder.and foam,and due to the increase in consistency,more aerogel"dusting"and foam damage will occur during the stirring process,which will reduce the strength of the test piece.（3）Using hydrogen peroxide as the foaming agent,when the aerogel content increased from0.5 wt%to 2 wt%,the foaming rate increased from 0.97 mm/s to 1.39 mm/s,and the thermal conductivity increased from 0.09077 w/（m·k）decreased to 0.06075w/（m·k）.When the aerogel content is 1 wt%,the pore diameter of the specimen is relatively concentrated,showing a normal distribution trend,the thermal conductivity is 0.07013 w/（m·k）,and the compressive strength is 0.88 Mpa,and the comprehensive performance is better.（4）When the hydrogen peroxide content increased from 7 wt%to 9 wt%,the relative volume of foaming increased from 51.25%to 60.78%,the foaming rate increased from1.25mm/s to 1.75mm/s,and the thermal conductivity increased from 0.07013 w/（m·k）drops to 0.05787w/（m·k）.Excessive temperature and foaming agent content are not conducive to cost saving and safe production.When the temperature is 30°C and the hydrogen peroxide content is 7%,the overall performance of the test piece is better and the production conditions are easier to control.（5）A large amount of fly ash will lead to loose pore wall structure of AGFC,and the probability of connected pores will increase greatly.When the substitution amount of fly ash is 40%,adding 0.3 wt%of alkali activator can stimulate the activity of fly ash in AGFC,make the pore wall structure more compact,the circularity of the pores is close to 1,and its mechanical Performance and water resistance have been improved.The dry density of the specimen is 277kg/m~3,the compressive strength of the standard curing 28d is 0.73MPa,the thermal conductivity is 0.052w/（m·k）,the water absorption rate is 42.6%,and the softening coefficient is 0.77.The performance of each bulk density level meets the requirements of JG/T266-2011"foamed concrete"standard requirements.