Study on pore structure and thermal conductivity of aerogel enhanced porous geopolymers

Aerogel is a kind of nanoscopic materials aggregated from thermal insulating material with its thermal properties substantially enhanced. Considering the high price, a small amount of aerogel (0 -8 mass%) has been added into geopolymer pastes to produce aerogel-enhanced porous geopolymers (APG) with thermal conductivity < 0.055 W center dot(m center dot K)(-1). The effects of aerogel on viscosity, geopolymerization, stability, bulk density, mechanical and thermal properties of geopolymers have been studied. Results show that the addition of aerogel increases the viscosity of APG pastes and aerogel could stably exist in APG without reacting with alkaline activator within. Due to its frangibility, overdosed aerogel (> 8 mass%) would result in a decline of compressive (sigma) and flexural strength (delta) of APG to lower than 0.3 MPa and 0.2 MPa, respectively. However, a desired content of aerogel (about 6 mass%) could reduce the thermal conductivity (lambda) of APG to 0.05 W center dot (m center dot K)(-1) and keep the mechanical properties satisfying the standard of JC/T 2200-2013 (sigma > 0.3 MPa and delta > 0.2 MPa for 180 kg center dot m(-3)) in the same time. The heat transfer simulation indicates that aerogel could enhance the thermal resistance of APG in a temperature difference of 25 degrees C.

Automated summary

The addition of aerogel can enhance the thermal resistance of aerogel-enhanced porous geopolymers (APG), but excessive addition can lower their mechanical strength. A content of approximately 6% aerogel can meet both the thermal conductivity and mechanical performance standards of APG.