Life cycle assessment of rammed earth made using alkaline activated industrial by-products

Abstract

Given increasing environmental concerns, lower energy building materials are being developed to reduce greenhouse gas emissions. The ancient technique rammed earth has been combined with modern industrial waste products to both reduce greenhouse gas emissions and reduce waste. The new rammed earth mixes have been developed using alkaline activation (sodium hydroxide) of industrial by-products: fly ash, ground granulated blast furnace slag and silica fume. This paper explores the ‘cradle-to-gate’ life cycle assessment, assessing global warming potential of these rammed earth materials, considering acquisition of raw or recycled materials and processing to final product of residential building envelope. These are compared with commonly used building envelope materials, brick veneer and cavity brickwork, and the more common rammed earth variety, cement-stabilised rammed earth. Results show that greenhouse gas emission savings can be made using these rammed earth mixes compared to the control building materials while achieving comparable or better material properties. Greenhouse gas emissions associated with the building envelope materials are reduced by more than half or one third when compared to cavity brickwork or brick veneer respectively. Following testing of the waste products in surplus in a given area, the same process could be followed for any geographic location.