Variation of Shear Strength Properties with Organic Fraction in Unsaturated Synthetic Municipal Solid Waste

The proportion of the constituent materials in fresh MSW varies from location to location; as does the attendant shear strength. Highly heterogeneous nature of MSW composition makes it difficult to compare shear strength properties of samples from two different locations. The wide variation in shear strength properties is attributed to the heterogeneous nature of the composition and the level of biodegradation of MSW. MSW shear strength found in literature typically indicates an increase in the angle of friction of with degradation. However, it is not very clear what contributes to the cohesive properties in MSW. Cohesion values from the published studies are often difficult to interpret and compare due to the limited information on the composition of the tested materials. The research described in this paper is an attempt to understand how the shear strength properties vary with the rapidly biodegradable organic fraction in MSW. During this research a series of laboratory tests were conducted on unsaturated synthetic MSW using an automated direct shear testing machine. The preliminary results from this investigation revealed that the increase in the fraction of organics (such as food waste) can result in decreased friction and increased cohesive properties in MSW.