Lightweight porous geopolymers from waste red brick precursor and synthetic foaming admixture

Abstract

Geopolymers are associated with a high potential to replace traditional Portland cement. Up to now, research has been ongoing on alternative precursors with wide availability, low cost, and low environmental impact. Attention is paid to ashes, industrial by-products, and construction and demolition waste. Sophisticated materials with high porosity and improved physical or mechanical properties are developed to enhance the application of geopolymers. In this paper, the waste red brick is used as a precursor to produce highly porous geopolymers. Here, porous geopolymers on waste brick precursor and synthetic foaming agent were developed for the first time. Red waste brick was ground to powder particles and activated with NaOH solution. A porous structure was obtained by a pre-foaming technique where geopolymer slurry was mixed in the foams. Physical and mechanical properties were evaluated depending on mixture composition and foaming agent content. Porous geopolymers with densities from 240 to 1200 kg/m3 were obtained. The pore structure of obtained materials was characterized. Reduced density and characteristics of red clay precursor summarised in low compressive strength which was from 0.04 to 0.4 MPa.