MATEC Web Conf.
Volume 337, 2021PanAm-Unsat 2021: 3rd Pan-American Conference on Unsaturated Soils
|Number of page(s)||7|
|Section||Fundamentals and Experimental Investigations|
|Published online||26 April 2021|
A comparative study of soil-water characteristic curves for compacted lateritic soil – bacillus coagulans mixtures
1 Civil Engineering Department, Ahmadu Bello University, Zaria, Nigeria
1* Civil Engineering Department and Africa Centre of Excellence on New pedagogies in Engineering Education, Ahmadu Bello University, Zaria, Nigeria
2 Civil Engineering Department, University of Jos, Nigeria
* Corresponding author: email@example.com
A comparative study of soil-water characteristic curves (SWCCs) for compacted lateritic soil ̶ Bacillus coagulans (B. coagulans) mixtures for municipal solid waste (MSW) application was studied. Soil treatment was performed at approximately about one-third pore volume of the microbes (i.e., B. coagulans) for suspension densities of 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, correspondingly. Soil specimens were prepared at optimum moisture content (OMC) of British Standard light (BSL) compaction energy. Cementation reagent was applied on the compacted soil and permitted to penetrate until partial saturation was achieved. A set-up of pressure plate extractor was employed to measure the volumetric water content, θ (VWC) in the laboratory for varying matric suctions with a minimum of 10 kPa up to a maximum of 1,500 kPa. The unsaturated hydraulic conductivity (UHC) and VWC were assessed using Brooks - Corey (BC) and Fredlund - Xing (FX) models. Largely, BC and FX models overrated the VWC. Also, the VWC decreased with higher matric suction for the two models considered and the laboratory measured values. The UHC predicted for matric suctions of 500 and 1,500 kPa initially decreased for B. coagulans suspension density up to 1.2×109 cells/ml for BC and FX models, with the exception of a few cases, but thereafter increased with increase in microbial density. For FX model at 1,500 kPa, UHC values of 2.42×10–9, 2.02×10–9, 9.31×10–10, 8.09×10–10 , 1.29×10–9 and 2.27×10–9m/s were recorded at 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, respectively. In the case of BC model, values of 2.26×10–17, 1.41×10–14, 2.2×10–14, 4.6×10–19 , 3.25×10–17 and 2.45×10–14m/s were recorded at 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, respectively. Thus, the FX model met the design maximum hydraulic conductivity value of 1 x 10–9 m/s requirement for MSW system when lateritic soil was treated with B. coagulans suspension density of 1.2×109 cells/ml, while the BC model satisfied the requirement for all the microbial densities considered and it is recommended for modelling of UHC of lateritic soil admixed with B. coagulans for MSW containment application.
Key words: Bacillus coagulans / Brooks - Corey model / Fredlund -Xing model / Lateritic soil / Unsaturated hydraulic conductivity / Volumetric water content
© The Authors, published by EDP Sciences, 2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.