In this paper, we report a new and convenient method for the synthesis of insulating aer-ogel by recycling solid waste coal gangue, which can reduce the industrial production cost of silica aerogels and realize high value‐added utilization of solid waste. Sodium silicate was prepared from a cheap industrial waste coal gangue as the precursor for silica aerogels, which was used for silica wet gel preparation by a one pot method; this method of solvent exchange/surface modification was carried out quickly by mechanical stirring process, and the wet gels derived from coal gangue were dried under ambient pressure condition. A high surface area (~748 m2/g) nanostructured aerogel with a 3D open porous microstructure was synthesized, which exhibits a low density (~0.18 g/cm3) and a superior thermal insulation performance (~0.033 W∙m−1∙K−1). More significantly, the synthetic yield of silica aerogel powder by recycling coal gangue can reach 92%. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

为了更好地提升气凝胶砂浆(Aerogel Cement Paste,ACP)在模拟隧道火灾(1100℃,2.5 h)中对自密实混凝土(Self-Compacting Concrete,SCC)的保护作用,以现场施工养护方法为基准,研究了湿养时间(7 d至28 d)对ACP复合SCC隧道火灾抗力的影响

为了分析气凝胶砂浆对隧道混凝土的防火隔热效果,研究了隧道火灾下气凝胶复合混凝土强度随时间退化的规律。首先在气凝胶体积掺量为骨料体积的60%条件下制备出具有防火涂层潜力的砂浆,涂覆在自密实高性能混凝土试件上制成气凝胶复合混凝

由气凝胶材料的特性入手,首先评述了气凝胶材料的保温隔热和光催化性能,认为气凝胶可以替代普通轻质骨料（如浮石和珍珠岩等）制备轻质隔热混凝土;其次总结了气凝胶结合砂浆及其复合混凝土的研究现状,认为气凝胶砂浆及其复合混凝土的研究不仅可以体现其优异保温隔热性能,也可以结合气凝胶复合材料的光催化性能,制备具有光催化性能的保温隔热砂浆;最后提出了上述方面发展领域尚待解决的一些关键科学问题,确定使用要求下,气凝胶复合混凝土结构耐久性特征的指标与参数等。

为研制新型环境友好型建筑保温隔热材料,试验探讨了不同骨料（气凝胶+砂）掺量对SiO2气凝胶保温隔热砂浆性能的影响。基于体积法设计砂浆配合比,其中骨料体积取总体积的50%,55%,60%,65%,70%,气凝胶体积取骨料体积的60%。结果表明:当骨料掺量为60%时,导热系数最低为0.15 W/（m·k）,密度为1 243 kg/m~3,28 d的抗压、抗折强度为9.14 MPa和3.14 MPa,吸水率为16.6%。采用扫描电镜SEM法对砂浆的微观结构进行了分析,从微观角度验证了保温隔热砂浆的基本性能。

In high-performance concrete (HPC) subjected to high temperature during tunnel fires, the build-up of vapor pressure due to dehydration of the cement hydration products cannot be relieved due to the very low porosity and permeability of this type of concrete, often resulting in explosive spalling. Explosive spalling may cause devastating damage of the tunnel structure, which threatens both, civilians and emergency response units. This work suggests a potential application of silica aerogel in the protection of concrete linings, which consists in decorating the surface of HPC structures with a highly-insulating aerogel-cement mortar layer, with the aim of delaying the heating of the HPC and extending the performance of the main concrete structure of the tunnel under fire. The main aim of this study is investigating the impact of the microstructure, with special focus on the pore structure, on the thermal conductivity and the mechanical properties of the aerogel mortars. In particular, the integrity of the aerogels in the mortars, both in the mixing process and the possible long-term chemical degradation, was a main concern. Finally, a preliminary test of the performance against fire spalling was performed. While aerogel-containing mortars were able to protect HPC cubes from fire spalling under a specific thermal loading protocol, the thermal conductivity and the mechanical properties obtained were similar to those of cellular concrete in the same range of total porosity. A possible explanation of the lower-than-expected insulation performance is the partial degradation of the aerogel filler by reaction with the alkaline pore solution of the mortars. Implications of these new findings on aerogel-cement mixtures are also discussed.
© 2019 Elsevier Ltd

Owing to its exceptional physical properties, silica aerogel is regarded as an attractive candidate material for building insulation applications; however, the widespread adoption of silica aerogel is limited by its inherently brittle nature and related sub-micrometre dust release. In this paper, the poor mechanical properties of silica aerogel were improved by combining the silica phase and cementitious materials to reach engineering strong composites and maintain relatively low thermal conductivity. The mechanical properties, durability (freeze-thaw resistance, water resistance and drying shrinkage) and thermal conductivity of the silica aerogel-cement composites were comprehensively studied. The composites show improved mechanical properties as compared to pure silica aerogel, but this decreases with the increase of silica aerogel content. With respect to the durability, surprisingly, the silica aerogel can efficiently improve the frost and water resistance of the composite, which might be benefited by the strong hydrophobicity of the silica aerogel. The optimal performance of the composite is observed at 60 vol.% aerogel loading. The thermal conductivity, compressive strength, flexural strength and bonding force are 0·065 W/(m/K), 3·81 MPa, 2·23 MPa and 0·27 MPa, respectively, and the drying shrinkage of the composite is only 0·12% after 90 d.
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