Abstract
This paper investigates the development of geopolymer foam boards, using perlite wastes as raw material. This type of lightweight materials combines the geopolymerization technology with the foaming process. The mechanism of foaming is based on the generation of a gas that is retained by the geopolymer matrix in the form of individual or interconnected voids. In this study, the inorganic foaming agent is hydrogen peroxide (H2O2), which is added into the initial paste in different quantities by mechanical stirring. The produced porous materials have effective densities between 408–476.5 kg/m3, thermal conductivities between 0.076–0.095 W/m.K and different type of microstructure, depending on the concentration of the activator and the foaming agent content. To assess the porosity and the size distribution of the voids, image processing techniques were applied on digital images of the samples. According to these results, the synthesized lightweight materials exhibit similar or even better thermal properties than the current concrete porous materials.
Highlights
This paper investigates the development of geopolymer foam boards, using perlite wastes as raw material
Concerning the thermal conductivity of the foam boards (Figure 2b), the results reveal a similar trend to the apparent density curve, presenting a rapid decrease on thermal conductivity values at low H2O2 contents (0.05 to 0.25%)
In the region between 0.25 and 1% H2O2 content, thermal conductivity seems to reach a plateau around 0.08 W/mK for 2 M of NaOH concentration and 0.095 W/mK for 4 M
Summary
This paper investigates the development of geopolymer foam boards, using perlite wastes as raw material. This type of lightweight materials combines the geopolymerization technology with the foaming process. The produced porous materials have effective densities between 408–476.5 kg/m3, thermal conductivities between 0.076–0.095 W/m.K and different type of microstructure, depending on the concentration of the activator and the foaming agent content. To assess the porosity and the size distribution of the voids, image processing techniques were applied on digital images of the samples According to these results, the synthesized lightweight materials exhibit similar or even better thermal properties than the current concrete porous materials. AAC is produced by foaming Portland Cement (OPC) with the use of hydrogen gas that is generated from aluminum powder addition [5]. Even though AAC production suffers from some disadvantages, such as the requirement for increased plant precautions due to the explosive nature of hydrogen gas, as well as difficulties in the production control and high energy consumption [5,6,7,8,9]
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