Settlement Behaviour of Peat Reinforced With Recycled Waste Tyre Granules

Peat is a problematic soil for having high organic content and high water content in nature. This soil is normally avoided for construction as it shows significant primary and secondary settlement even under moderate load. Ground improvement is conducted to improve peat properties by using cement column, soil replacement, chemical and biological stabilisation and others. However, some of these methods have their drawbacks for being non-sustainable to the environment, very costly, ineffectiveness and slow result performance. Alternative method using recycled waste tyre granules is seen as an innovative approach to reduce the settlement behaviour of peat in a more sustainable way. This paper investigates the effect of waste tyre granules on the settlement behaviour of peat. One-Dimensional consolidation test is carried out on natural sample and samples added with 5 % waste tyre granules with and without addition of sand as filler. The settlement curves for all samples do not show distinct separation between primary and secondary compression stages when using Casagrande’s method. Sample which is reinforced with 5 % waste tyre granules and sand has lower compression index and swelling index compared to other samples. The coefficient of volume of compressibility for all samples is reduced with increasing stress levels.

The effect of moisture content and alkalinity on the anaerobic biodegradation of pit latrine sludge

This study investigated the effect of additional moisture and/or alkalinity on the rate of anaerobic digestion in samples of material obtained from pit latrines. In modified serum bottle tests it was shown that poor gas production rates were observed from all experiments with material collected at the lower part of one pit. Using material from the top layer of a second pit it was shown that experimental bottles produced significant amounts of gas for all treatments. Analysis of data indicated that treatment with additional alkalinity had no discernible effect on anaerobic gas production rates, but that there was some correlation between moisture content and gas production rate. These results did not support the hypothesis that low pH buffering capacity was a limiting factor in the rate of digestion of pit latrine sludge, but confirmed that low moisture content could reduce the rate of stabilisation. This implies that increasing the moisture content in a pit latrine has the potential to increase biological stabilisation rates in the pit when the material is not already well-stabilised.