Study on pore structure and thermal conductivity of aerogel enhanced porous geopolymers
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Study on pore structure and thermal conductivity of aerogel enhanced porous geopolymers Duanle Li1,2 · Dongmin Wang2 · Yong Cui2 Received: 5 May 2020 / Accepted: 28 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract 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 8 mass%) would result in a decline of compressive (σ) and flexural strength (δ) 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 (λ) of APG to 0.05 W· (m · K)−1 and keep the mechanical properties satisfying the standard of JC/T 2200-2013 (σ > 0.3 MPa and δ > 0.2 MPa for 180 kg · 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 °C. Keywords Aerogel · Porous geopolymer · Insulating materials · Thermal conductivity
Introduction Nowadays, building energy consumption is a huge concern on the nation’s policies of energy conservation and emission reduction, especially within the climate changes context. Energy-efficient building with higher energy savings, less strains on material resource and lower pollution is becoming an increasingly important and urgent need in human society. It has been shown that compared with solar photovoltaics and wind energy, thermal insulation installation is a much * Dongmin Wang [email protected] Duanle Li [email protected] Yong Cui [email protected] 1
Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China
2
more direct and cost-effective method to increase energy efficiency requirements [1]. Therefore, many efforts are being made to replace ordinary thermal insulation materials [2] by developing new materials with low-heat transfer coefficients [3–5] in order to find the best solution for energy-saving purpose. Improving building material performance through nanomaterials is an important means to improve building energy efficiency [6]. Aerogel is a nanoporous silica material with a porosity of 85.0–99.9% and a density of about 100 kg · m−3, which has extremely low thermal conductivity (0.01–0.02 W · (m · K)−1). It is worth noting that aerogel materials have good fire resistance and sound insulation performance [7]. Due to the nanoscale framework and nanoscopic pores, aerogel is considered as an insulating material in the field of nanotechnology [4–6]. In addition, existing studies have proven that aerogels can effectively reduce the thermal conductivity of materials [5, 8]. However, when the material co
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