Development of Soil-Biochar Mixtures as a Sustainable and Multi-Functional Roadway Fill Material

The goal of this research is to develop soil-biochar mixtures as a sustainable, economical, and multi-functional lightweight fill material for roadway embankment applications. Many lightweight fill materials have limited applications due to their high costs and energy-intensive manufacturing processes. Biochar is an environmentally friendly and economical carbon-rich product formed by combusting waste biomass (e.g., forestry and agricultural residues) in an oxygen-limited environment through a process known as pyrolysis. Since biochar has a much lower density than typical soils, biochar is suitable for roadway applications as a lightweight fill material. Furthermore, biochar has a high surface area and porosity and excellent ability to adsorb a variety of contaminants, which has been amended in the soil to increase soil water retention, reduce potentials of soil cracking and erosion, adsorb contaminants, and enhance soil aggregation. Due to these favorable properties of biochar, soil-biochar mixtures have high potential to serve as a multi-functional lightweight fill material for roadway embankment applications to decrease the applied load to foundation soil, enhance the factor of safety against slope stability failure, reduce the soil erosion and cracking potential, and remediate the stormwater runoff. This research investigates the mechanical and hydraulic properties of sand-biochar mixtures as a sustainable and multi-functional fill material for roadway embankment applications. 1D consolidation tests instrumented with bender elements will be performed to investigate the modulus and compressibility of sand, biochar, sand-biochar mixtures, and sand-biochar mixtures treated by cement. Different mixing ratios between sand, biochar, and cement will be investigated. Next, the hydraulic conductivities of sand, biochar, sand-biochar mixtures, and sand-biochar mixtures treated by cement will be conducted using an automated permeameter. Based on these test results, an optimal mixing ratio (i.e., high mechanical strength and excellent drainage property) between sand, biochar, and cement will be selected for the lightweight fill applications. Maintaining the statewide highway embankment systems is a significant challenge with considerable impacts on the limited budgets of state DOTs. Also, numerous embankments on soft soils in Region 6 rely on pile installation and ground improvement, which requires complex and pricey construction. Due to increasingly stringent stormwater regulations, many DOTs are required to remediate stormwater for water runoff, metals, bacteria, and other pollutants. Therefore, the development of lightweight fill material composed of sand-biochar mixtures, which have potential in reducing erosion and cracking potential, retaining containments, and reducing stormwater runoff, is relevant to DOTs mission on sustainable design of roadway embankment.

• Record URL:
  https://transet.lsu.edu/wp-content/uploads/sites/16/2021/08/21GTLSU02.pdf
• Supplemental Notes:
  • 21GTLSU02

Language

• English

Project

• Status: Active
• Funding: $60000
• Contract Numbers:

  69A3551747106

• Sponsor Organizations:

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Managing Organizations:

  Transportation Consortium of South-Central States (Tran-SET)

  Louisiana State University
  Baton Rouge, LA  United States  70803
• Project Managers:

  Mousa, Momen

• Performing Organizations:

  Louisiana State University, Baton Rouge

  P.O. Box 94245, Capitol Station
  Baton Rouge, LA  United States  70803
• Principal Investigators:

  Lin, Hai

• Start Date: 20210801
• Expected Completion Date: 20230201
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers Program

Subject/Index Terms

• TRT Terms: Fills; Lightweight aggregates; Mix design; Sand; Soil aggregates; Waste products (Materials)
• Subject Areas: Construction; Highways; Materials;

Filing Info

• Accession Number: 01787558
• Record Type: Research project
• Source Agency: Transportation Consortium of South-Central States (Tran-SET)
• Contract Numbers: 69A3551747106
• Files: UTC, RIP
• Created Date: Nov 10 2021 8:23AM