Fernando Pacheco Torgal

Foam geopolymers : state of the art and preliminary experimental results

Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus increasing building energy efficiency is the most cost effective way to reduce emissions. The use of thermal insulation materials constitutes the most effective way of reducing heat losses in buildings thus reducing heat energy needs. These materials have a thermal conductivity factor, k (W/m.K) lower than 0.065 while other insulation materials like for instance aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants, additionally, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper reviews literature on foam geopolymers that could constitute a lower toxicity alternative to current commercial insulator. Current methods use foaming agents (blowing agents) such as hydrogen peroxide (H2O2), sodium perborate (NaBO3), silica fume, powder alumina. Results of an experimental research on foam hybrid alkaline cements are reported.