The thermal and mechanical properties of concrete in which normal weight aggregate has been substituted with lightweight aggregates were investigated. The properties were found to be dependent on the volume fraction of the lightweight aggregate, as well as on the nature and quality of the aggregate. The addition of lightweight aggregates resulted in a decreased thermal conductivity, as well as a decreased thermal diffusivity in all samples. The compressive strength ...
Ambient pressure dried hydrophobic silica aerogel monoliths were prepared via simultaneous solvent exchange and surface modification in order to minimize volume shrinkage and density. At room temperature, the obtained silica aerogels had a low density of 0.096 g/cm³, a high surface area and hydrophobicity, and a low thermal conductivity of 0.0217 W/m·K. The effect of heating on these properties was also determined. After the aerogel had been heated to 300°...
Ultralow density silica aerogels were formulated by sol-gel process using tetramethyl orthosilicate as the precursor. A supercritical drying step was performed using acetonitrile solvent extraction. These aerogels were found to have a high specific surface area (~812m2/g) and they were found to be excellent thermal insulators with thermal conductivities ranging from 0.024 to 0.043 W/m K at temperatures up to 400oC....
The authors present a novel method for the preparation of highly porous tannin-based meringues by shear mechanical mixing of tannin, hexamine, and Kolliphore® ELP in water. The liquid foam was then cured in an oven at 85oC for 24 hours. The resultant solid foams were found to be homogeneous and they were also found to have similar thermal conductivity and other physical properties to tannin-based foams prepared by more traditional methods....
The authors prepared silica aerogel/polyurethane composites by two different methods for the comparison of the two methods. The objective was to study the thermal insulation and hydrophobic properties of the composites to evaluate their potential for use as fabric membranes. It was found that the composites are better thermal insulators than polyurethane alone, and that they also have improved hydrophobic properties. It was also determined that the thermal conductivities ...
