Indigenous Technique of Biochar Production and Effect of Biochar Application on the Geotechnical Properties of the Expansive Soils

Abstract

Expansive soils have been a source of risk to human beings as they causes huge economic loss including damage to buildings, roads and other civil infrastructures because of their low compressive strength and excessive settlement characteristics. One of the available options is to replace such soils before starting any civil engineering construction but looking to huge costs involved in replacement; it is generally not practiced nowadays. Another viable alternative is to improve the engineering properties of such soils through stabilization. The conventional methods of stabilization make use of cement, lime, fly ash, rice husk ash, sawdust ash and other fibrous materials. Researchers are always finding alternative methods of soil stabilization making use of modern scientific techniques which are cost-effective as well as eco-friendly in nature. The present study focuses on producing biochar from agricultural crop residues and making use of it for stabilizing the expansive soils. India being an agricultural country produces a large volume of crop residues which creates an environmental problem in absence of proper management and disposal system. Indian farmers generally practice stubble burning in their fields which causes emission of greenhouse gases in the atmosphere and at the same time damage to the soil biota. A simple indigenous method of producing biochar has been developed wherein the crop residues are converted into biochar which is further applied to expansive soils as a stabilizing agent to improve the physical, chemical and engineering properties. In India, not much work has been carried out hitherto on biochar application to soils. The process of making biochar and the effects of utilizing biochar on the properties of expansive soil have been presented in this paper, which will prove useful for the Indian context where large quantities of agricultural wastes are produced that create environmental air pollution when burnt openly in fields.