Pore characteristics in one-part mix geopolymers foamed by H2O2: The impact of mix design

Publication date: 15 September 2017
Source:Materials & Design, Volume 130
Author(s): Ailar Hajimohammadi, Tuan Ngo, Priyan Mendis, Tuan Nguyen, Alireza Kashani, Jannie S.J. van Deventer
In geopolymers foamed by H2O2, it is important to consider the impact of mix design on both geopolymerisation reaction and the H2O2 foaming reaction to control the porosity of the geopolymer foam matrix. In this paper, the effect of mix design on both reactions is discussed and correlated with the properties of the resulting geopolymer foams. It is found that when the mix design provides a chemically stable environment for the foaming reaction and simultaneously facilitates rapid setting of the binders, it results in homogeneously distributed fine pores within the matrix. The homogeneity of pore distribution is determined by a non-destructive test and correlated with the thermal conductivity results. It is suggested that for better thermal insulating properties, geopolymer foams are preferably poured and cured parallel to the heat flow direction. The size distribution of pores is shown to be a critical parameter in determining the strength of foams, and the mesoscale-based finite element analysis is performed to create a predictive tool for correlating the pore size distribution of geopolymer foams with their mechanical properties.

Graphical abstract

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