ABSTRACT
The global soil stabilisation market is forecast to grow to $35 billion by 2027 driven primarily by infrastructure and construction activities and exacerbated by the increasingly urgent need to adapt to climate change. Naturally sourced biopolymers are a promising low carbon ‘green’ stabilising agent, achieving higher strength in stabilised soils than cement and at similar cost. However, widespread uptake of biopolymers is impeded by the fact that they typically suffer from (a) poor water resistance and (b) poor resistance to biodegradation over time. This paper presents interim results from a research study into novel biopolymer treatment processes which are applied at or subsequent to the soil/biopolymer mixing stage with the aim of enhancing resistance to water and biodegradation while involving the addition of only small volumes of natural materials. The specific approach described in this paper aims to minimize the interaction of vulnerable hydrophilic functional groups in the biopolymers with water through acetylation, whereby the hydrophilic groups are replaced by natural hydrophobic acetyl groups. Three mixing protocols are proposed and this paper examines the first protocol where the acetylation agents are added at the same time as the biopolymer is added to the soil. While this is the simplest process procedurally, results demonstrate that the strength on wetting is lower than non-acetylated chitosan treated soil. Improved performance is anticipated for the other protocols.
