Cement paste foamed by the addition of aluminiun powder with metakaolin and sepiolite

Abstract

Spanish Technical Building Code requires thermal insulating materials inside the vent cameras of buildings façades, having low fire reaction (for instance, belonging to class A). Current thermal insulating materials are usually based on polymer foams, with the added disadvantage of producing toxic gases in case of fire. So, it's necessary to develop new incombustible materials of low density for insulating which can be sprayed. Cement mortar based foams are good candidates.This paper analyzes the effects of type of cement selection or metakaolin (MK) and sepiolite (SP) addition on cement pastes foamed by aluminum powder, for determining the properties of fresh and hardened mortar. The water retention and the rheology of the fresh foamed cement pastes were studied to characterize the fresh mortar. Finally, pore network in the hardened foamed mortar was studied by imbibition methods. It is concluding that incorporating siliceous fly ashes (SFA) in ordinary Portland cement besides additions of MK or/and SP, the foamed mortar have lower bulk density and higher closed porosity. These properties are important for the thermal insulation materials applying in the vent cameras of building façades.