Shear and compression behaviour of undegraded municipal solid waste

To ensure stability of a construction the physical properties of its components have to be well known. In a landfill, waste presents the largest structural element and controls both the stability and integrity of the lining system. In spite of this critical role there is a dearth of knowledge on behaviour of waste as an engineering material. Waste variability and changes in waste stream aggravate the assessment of waste mechanical properties. In a literature review the main influences on shear behaviour of municipal solid waste (MSW) were identified. Design values and recommendation for shear parameter were summarised. To assess mechanical behaviour in a systematic way the use of a classification system was deemed crucial for a comparison of different findings from literature and a categorisation of waste in regard to its composition. A framework for a classification system was introduced. Main elements of a comprehensive classification system were identified in a literature review and discussed, and data from literature was applied to the classification framework. For the validation of a classification system, municipal solid waste was examined in an in-situ waste sorting analysis and also applied to the framework. The findings from the waste sorting and the classification system were also used to develop a family of synthetic waste to gradually examine the influencing factors on waste mechanical behaviour. For this, the materials, size ranges and shapes of waste components identified in the waste sorting analysis were reduced to a minimum but still representative amount. A range of synthetic waste compositions was engineered and tested in a large-scale shear device. Compression tests were also conducted in a large compression cell. The results from the laboratory testing were compared to values from the literature and MSW mechanical behaviour was subsequently discussed in view to potential changes from changing waste streams. The results from shear and compression tests (constrained and shear modulus) on synthetic waste were linked to the classification system and trends of the mechanical behaviour in relation to the tested synthetic waste compositions were identified. A framework for classifying MSW and comparing waste mechanical behaviour was presented and demonstrated. A family of synthetic wastes was engineered and tested in shear and compression tests. The results were comparable to values from the literature. Further research is recommended to refine the synthetic waste and the classification.