Exploring mineral–organic interactions for eco-friendly concrete alternatives: a radical concept

Abstract

Concrete is central to the civil construction industry worldwide, which is facing increasing governmental, social, and economic pressure to alleviate its considerable environmental impact. This impact centres around Portland cement, the main binder of concrete. The production of a single tonne of Portland cement generates 0.9 tonne of CO₂ gas along with other negative environmental impacts. In the quest for alternate construction materials, there is much focus on artificial geopolymers which use aluminosilicate-based binders, the production of which does not liberate large amounts of CO₂. However, due to the use of dangerous alkaline chemicals and high curing temperatures, industry is reluctant to implement artificial geopolymers despite their superior material properties. The research into replicating natural geopolymers appears to be in its infancy, possibly due to the underappreciated interaction between organic and mineral fractions. However, mineral–organic interactions are well researched, and the materials produced have considerably favourable properties. This work proposes the application of free radical chemistry to enhance and accelerate mineral–organic interactions to produce analogues of natural rock. The use of free radicals greatly reduces the energy requirements for reactions. They also efficiently degrade organic intermediates and promote mineral polymerisation. The benefits of these rock analogues lie not only in their material properties but also the potential re-use of waste building materials such as iron, aluminium, and glass. Therefore, the environmental impact of these materials will be substantially lower than that of concrete, with superior material properties. The implications of this study is a shift in conventional thinking away from current Portland cement-based construction materials to considering analogues of natural geopolymers.