Properties of Biochar-Amended Highway Soils: Biochar – An Eco-friendly Geomaterial

by Kalehiwot Nega Manahiloh, P.E., Ph.D., (M.ASCE), Assistant professor of civil and environmental engineering at the University of Delaware,
Paul Imhoff, P.E., Ph.D., (M.ASCE), Professor of civil and environmental engineering at the University of Delaware,

Serial Information: Geo-Strata —Geo Institute of ASCE, 2018, Vol. 22, Issue 5, Pg. 48-55

Document Type: Feature article

Abstract: Historically, geotechnical engineers have designed or modified soils and sediments to achieve particular strength, volume change, or flow characteristics. For example, lime and fly ash have been used to stabilize expansive soils. More recently, additives have been proposed to enhance biological activity, including adding compost to landfill cover soils to increase microbial methane oxidation, and injecting microbes into sands to enhance cementation. In the former case, organic carbon in compost is important for the desired activity. Natural soils not impacted by human activity have two types of carbon: "soft" carbon, which originates from decomposed plant matter, and "hard" carbon, which originates from combustion of plant residue. However, the soils and sediments encountered in construction often lack carbon when compared to natural soils. In situations where the microbial processes found in natural soils are desired, such as oxidation of methane in landfill covers or pollutant retention and transformation in highway soils, it may be useful to add soft and hard carbon in a manner that doesn’t compromise the strength and compressionrelated qualities of the site soil.

Subject Headings: Soil strength | Soil properties | Ashes | Carbon fibers | Soft soils | Soil compression | Soil pollution | Microbes


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