Geotechnical Characterization of Compost Based Biocover Materials: Fid-Bau Portal

Geotechnical Characterization of Compost Based Biocover Materials

Khoshand, Afshin / Fall, Mamadou

Abstract Landfills are one of the major sources of methane ($ CH_{4} $) emission which is a very potent greenhouse gas. The use of a natural process for microbial $ CH_{4} $ oxidation through biocovers provides a source reduction of $ CH_{4} $ emission. Previous studies have mostly focused on biochemical properties, and limited research has been conducted with regards to the geotechnical characterization of compost based biocovers. This paper presents the results of a comprehensive laboratory investigation on pure compost and compost–sand mixtures (with mix ratio of 3:1, 1:1, and 1:3 w/w) to determine the compaction, shear strength, compressibility, and hydraulic and thermal conductivity properties of compost based biocovers. Direct shear and ring shear tests have shown that the cohesion (c) and friction angle (ϕ) are in the range of 2.1–19.7 kPa and 44.1°–54.7°, respectively. Based on the results of one dimensional consolidation tests, the coefficient of consolidation ($ C_{v} $) values are in the range of 1.71–0.63 $ m^{2} $/year, which is a function of the moisture and organic contents of the samples. The lowest hydraulic conductivity ranges from 6.09 × $ 10^{−8} $ to 1.78 × $ 10^{−7} $ cm/s which occur at optimum moisture contents. Thermal conductivity is measured under various porosities and moisture contents. By increasing the dry density and sand content of the mixtures, thermal conductivity increases. The results presented in this paper will contribute to a better understanding of the geotechnical behaviour of compost based biocover, and thus to a more cost-effective design of biocovers.