Iron- and calcium-based biogrouts for porous soils
Date of Issue2012
School of Civil and Environmental Engineering
Chemical grouts are often used to reduce the hydraulic conductivity of soil for seepage control purposes. However, chemical grouts can be expensive and environmentally unfriendly. Therefore, two new biogrouts or microbial-based grouting materials were developed. The first was a calcium-based biogrout, which contained urease-producing bacteria, calcium chloride and urea for the crystallisation of calcite due to enzymatic hydrolysis of urea. The second was an iron-based biogrout, which consisted of urease-producing bacteria, ferric chelate, and urea for the precipitation of ferric hydroxide due to enzymatic hydrolysis of urea. Both biogrouts reduced the hydraulic conductivity of loose clean sand from 5 × 10−5 to 1·4 × 10−7 m/s when the precipitated metal content was at 1·5% w/w or lower. The unconfined compressive strength of the treated specimens also increased. However, at a low metal content, the amount of improvement was still much less than that obtained by chemical grouting. Therefore, suitable geotechnical applications of the calcium-based and iron-based biogrouts at a precipitated metal content of 1·5% w/w or less would be mainly the bioclogging of porous soils for the sealing of aquaculture or wastewater treatment ponds and landfill sites, and for plugging of the piping in dams and retaining walls in sandy soil.
DRNTU::Engineering::Civil engineering::Water resources
Proceedings of the ICE - construction materials
© 2012 Thomas Telford. This paper was published in Proceedings of Institution of Civil Engineers: Construction Materials and is made available as an electronic reprint (preprint) with permission of Thomas Telford. The paper can be found at the following official DOI: [http://dx.doi.org/10.1680/coma.12.00002]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.