The dependence of thermophysical and hygroscopic properties of macro-porous geopolymers on Si/Al

Aerated geopolymers are low calcium alkali-activated materials with induced porosity. These materials are reported to have huge potential to modulate the thermal and hydric conditions within buildings. The performance of these materials as a passive hygrothermal controller depends on various factors. However, studies in this area are limited. This study investigates how Si/Al ratio impacts the thermal and hydric features of foamed geopolymers. The thermal conductivity of the samples increased as the Si/Al ratio increased. While the vapor permeability of the materials decreases with rising silicon content. This is because the pore network declines with Si/Al. The vapor permeability of the samples has values ranging between 7.55 to 6.37(10(-11))(Kg/m.s.Pa). The moisture buffer capacity also follows a similar trend with values from 4.17 to 6.81(g/m(2) %RH). The moisture absorption capacity also reduces when the Si/Al increases. Therefore, Si/Al ratio is a key factor that needs to be controlled to engineer aerated geopolymers for passive house applications.

Automated summary

Aerated geopolymers, with induced porosity, have the potential to regulate thermal and hydric conditions within buildings. The Si/Al ratio plays a key role in determining the thermal and hydric features of foamed geopolymers, as the thermal conductivity increases and vapor permeability decreases with higher silicon content.