Feasibility of peat soil stabilisation with solid waste material inclusions and biocementation treatments

This paper studies the stabilisation of a peat railway embankment foundation soil from East Anglia, UK, using solid waste material inclusions and biocementation treatments. Peats are weak, high water content soils which lead to construction problems, due to the high water content and poor engineering properties. Chemical peat improvement to improve its engineering properties is commonly relying on Portland cement, which absorbs water while forming cementing gels. However, due to the negative environmental impact of Portland cement, the civil engineering industry is seeking innovative, more environmentally friendly alternatives. This study introduces soil biocementation based on biomimetic precipitation of natural minerals. Specifically, heterotrophic carbonic anhydrase producing bacteria that sequester CO2 in the process are used. Solid waste/by-product materials such as wood saw ash, sawdust and ground granulated blast furnace slag filler/water absorbing materials are also used, as a means of contributing to solid waste management by waste recycling. The results indicate undrained shear strengths of 2-16 times higher than that of the untreated peat depending on treatment, although further study is needed to improve treatment homogeneity with possible modifications in the treatment protocol.