Effects of biochar on cement-stabilised peat soil

Peat is a type of soft soil with very high organic content, which makes it highly susceptible to extreme differential settlement due to the lack of structure. Although cement stabilisation is highly effective, it is not a common practice due to the high cost of treatment associated with the large amount of binder dosage required. In this paper, the use of a novel material, biochar as a potential partial replacement for cement and as an alternative filler to sand, was investigated. Biochar is more sustainable than traditional construction materials and has carbon sequestration ability. It could potentially be cheaper than cement or sand, depending on the source of feedstock used. Cement treated peat with sand was used as a benchmark to assess the performance of biochar enhanced cement treated peat. Unconfined Compressive Strength (UCS) tests were conducted to evaluate the strength of stabilised peat. The samples with biochar fragments finer than 75 μm performed notably better than samples with sand only, with over 50 % increase in compressive strength. Furthermore, it was found that the samples with 100 kg=m3 cement and 400 kg=m3 biochar had comparable performance to the control sample with 200 kg=m3 cement only, without biochar, highlighting the potential of biochar to partially replace cement. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) tests results showed that the mechanisms behind the performance gain in biochar samples are of both mechanical and chemical nature