Effect of Biochar Produced from Mesquite on the Compaction Characteristics and Shear Strength of a Clayey Sand
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ORIGINAL PAPER
Effect of Biochar Produced from Mesquite on the Compaction Characteristics and Shear Strength of a Clayey Sand Rojimul Hussain . Kishor Kumar Ghosh . Ankit Garg . K. Ravi
Received: 6 September 2019 / Accepted: 2 September 2020 Ó Springer Nature Switzerland AG 2020
Abstract Biochar is a carbon-rich and low microbial degrading material obtained after pyrolysis of biomass in the absence or limited content of oxygen. The impact of biochar on hydraulic properties of soil is extensively studied in agricultural and geotechnical or geoenvironmental engineering for potential application in bioengineered structures. While a little study is conducted to assess its effect on soil mechanical properties, especially shear strength. However, the effect of biochar on the combined shear strength and compaction characteristics of soil is not studied. The shear strength of biochar amended soil is thought to be related to the compaction characteristics. In addition, the effect of biochar on the shear strength of the soil is soil and biochar specific. In this study, an attempt was made to investigate and better understand the effect of biochar on the shear strength and compaction characteristics of a clayey sand for potential application in R. Hussain K. K. Ghosh K. Ravi (&) Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India e-mail: [email protected] R. Hussain e-mail: [email protected]
bioengineered structures. Standard proctor, direct shear and unconfined compression tests were conducted on bare soil and soil amended with 5, 10 and 15% (w/w) biochar. The experimental results revealed that the amendment of biochar from 5 to 15% (w/w) decreased the dry density and increased the shear strength parameters such as cohesion (c) and angle of internal friction (/) of the soil. While it decreased the undrained shear strength (cu) at higher compaction density ([ 0.95MDD) and increased at lower compaction density (\ 0.9MDD). Thus, in undrained condition, the initial compaction density has a strong influence on the shear strength of biochar amended soil. In addition, the increased c and / and decreased dry density in biochar amended soil is observed to increase the stability of slopes (hypothetical). The increase of c and / is believed to be due to the roughness and active chemicals (functional groups) present on the surface of the biochar. The decreased cu at higher density is believed to be due to the lubricating effect by the higher water content. Keywords Biochar Shear strength parameter Compaction characteristics Slope stability Undrained shear strength
K. K. Ghosh e-mail: [email protected] A. Garg Department of Civil and Environmental Engineering, Shantou University, Shantou, China e-mail: [email protected]
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Geotech Geol Eng
1 Introduction Biochar is a solid carbonaceous product obtained after pyrolysis or gasification of organic biomass in the absence or limited content of oxygen in a closed
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