Linn Ingunn Christie Sandberg

Synthesis of Hollow Silica Nanospheres by Sacrificial Polystyrene Templates for Thermal Insulation Applications

© 2013 Linn Ingunn C. Sandberg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Insulating and Strength Properties of an Aerogel-Incorporated Mortar Based an UHPC Formulations

With the increasing attention towards energy-efficient and zero emission buildings, improvement to concrete properties is becoming more and more significant in construction and building sectors. One such area is to enhance the thermal properties, while maintaining maximum strength of the material. Here, attempts were made to address this challenge by formulating mortar composites with low thermal conductivity while targeting a minimum compressive strength of 20 MPa at 28 days. For this purpose, aerogel was utilized in an ultrahigh performance concrete (UHPC) formulation to create new aerogel-incorporated mortar (AIM). It was found that AIMs possessing 50 vol% aerogel registered a compressive strength of 20 MPa, while displaying a thermal conductivity of ~ 0.55 W/(mK). By adding more aerogel to reach 70 vol%, while the thermal conductivity of the concrete decreased by ~ 20 %, a sharp decrease in strength to 5.8 MPa was observed. This represents only 1/30 of the original strength of the UHPC mortar. Further addition of aerogel till 80 vol% showed negligible compressive strength, attributing to the imbalance of the particle-matrix ratio in the mortar system, causing a decrease in adhesion of the binder-aggregates.

Development of Nano Insulation Materials for Building Constructions

The application of superinsulation materials (SIM) reaching thermal conductivities far below 20 mW/(mK) allows the construction of relatively thin building envelopes while still maintaining a high thermal resistance, which also increases the architectural design possibilities for both new buildings and refurbishment of existing ones. To accomplish such a task without applying vacuum solutions and their inherit weaknesses may be possible from theoretical principles by utilizing the Knudsen effect for reduced thermal gas conductance in nanopores. This study presents the attempts to develop nano insulation materials (NIM) through the synthesis of hollow silica nanospheres (HSNS), indicating that HSNS may represent a promising candidate or stepping-stone for achieving SIM. Furthermore, initial experiments with aerogel-incorporated concrete and the conceptual work concerning NanoCon are presented.