Preparation and Properties of Lightweight and Low Thermal Conductivity Aerogels Foamed Concrete

SiO2 aerogel is a kind of nano porous materials, with super light super thermal insulation properties, is one of the best quality the most light, the heat insulation property of solid materials, due to the large bubble content when the foam concrete formability is difficult to guarantee, so difficult to simply increase, and by adding aerogel preparation of aerogels concrete reduce the density and thermal conductivity, high cost of existence, density and lower thermal conductivity is limited.Through in the foam concrete mixed with light, porous, super hydrophobic aerogel powder, coefficient of thermal conductivity is lower than the air, is expected to be prepared in the case of low porosity density is small, low coefficient of thermal conductivity of aerogels foam concrete, the higher porosity when improve the formability of foam concrete, on the basis of prefabricated foam prepared foam concrete, by joining aerogel powder preparation of a new type of aerogel foam concrete, the preparation parameters on the properties of foam concrete aerogel.The research results are as follows:

(1) A new type of aerogel-foamed concrete was successfully prepared with aerogel as the filler and prefabricated foam mixing method, and its density and thermal conductivity were significantly reduced on the premise of meeting the requirements of compressive strength specifications.When the cement content is 222 kg /m3, the aerogel content is 13.0 kg /m3, and the foam content is 70%, the minimum density reaches 270.2 kg /m3, and the minimum thermal conductivity reaches 0.069 W /m•K.

(2) On the porosity of 40% gel foam concrete dry bulk density than the ordinary foam concrete was reduced by 58.6%, to meet the dry bulk density of 400 kg/m3, foam concrete needs only 66% of the aerogel porosity, while 82% of ordinary foam concrete need of porosity, can improve the formability and foam concrete compressive strength.

(3) The ratio of aerogels and bubbles has a great impact on the performance of aerogels foamed concrete. Under the condition of foam volume ratio of 50%, when the amount of aerogels increases from 9.2 kg /m3 to 22.1 kg /m3, the density decreases by 13.7%, the thermal conductivity decreases by 18.5%, and the compressive strength decreases by 0.91Mpa.

(4) There is a strong correlation between the dry volume density, thermal conductivity and compressive strength of aerogel-foamed concrete, and the empirical relationship between them is fitted, which can provide a reference for the prediction of engineering application performance.

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