Geopolymer foam concrete: An emerging material for sustainable construction

• A comprehensive review of current foam concrete technology and geopolymer technology.
• A concept of developing geopolymer foam concrete with great environmental benefits.
• A concrete with low cost, high strength/weight ratio and potential fire resistance.

The development of sustainable construction and building materials with reduced environmental footprint in both manufacturing and operational phases of the material lifecycle is attracting increased interest in the housing and construction industry worldwide. Recent innovations have led to the development of geopolymer foam concrete, which combines the performance benefits and operational energy savings achievable through the use of lightweight foam concrete, with the cradle-to-gate emissions reductions obtained through the use of a geopolymer binder derived from fly ash. To bring a better understanding of the properties and potential large-scale benefits associated with the use of geopolymer foam concretes, this paper addresses some of the sustainability questions currently facing the cement and concrete industry, in the context of the utilisation of foam concretes based either on ordinary Portland cement (OPC) or on geopolymer binders. The potential of geopolymer binders to provide enhanced fire resistance is also significant, and the aluminosilicate basis of the geopolymer binding phases is important in bringing high temperature stability. The standardisation (quality control) of feedstocks and the control of efflorescence are two challenges facing the development of commercially mature geopolymer foam concrete technology, requiring more detailed exploration of the chemistry of raw materials and the microstructural development of geopolymers.