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/m2%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.