Investigating the applicability of Renolith on lime - stabilized in-situ soils.
Kasekende, Romeo G
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To achieve the desired economic growth, Government of Uganda placed infrastructure development as one of its top priorities. Presently the Uganda government set its target to construct National highway or Express ways at rate of 20 km per year. Besides this, thousands kilometres of low volume roads under Local Government scheme are being constructed and being rehabilitated per year under Central Government aid. If an economical and effective solution to upgrade the subgrade is used this can make a contribution to a longer lasting road which in turn can contribute to the economic growth of Uganda. Towards these efforts, a bio enzyme branded as Renolith was employed towards improving an in-situ subgrade soil. A comparative study was carried out to stabilize the local soil with conventional method, that is, lime stabilization and using Bio enzymes branded as Renolith. Bio-enzymes are normally used in soil stabilization as these are natural, non-toxic, non-flammable, non-corrosive liquid in form and prepared from vegetable extracts. Thus, Bio enzymes are increasingly providing a new niche in the field of soil stabilization. Experimental studies were carried out on the local virgin soil. The physical and index properties of virgin soil and soil mixed with lime were studied by adding Renolith in different proportions. The initial lime consumption (ICL) required for the virgin soil samples was determined at 2%. Further, two percentages below and above the ICL were tested in combination with the Renolith additive i.e. (0.5%, 1%, 2%, 4%, 6%) to observe Renolith’s effects in stabilization. The California Bearing Ratio (CBR), Standard Proctor (MDD and OMC) and Unconfined Compressive Strength (UCS) tests were carried out on the soil treated with lime and Renolith. Renolith was added in proportions of 1%, 3% and 5% by weight of lime. From the experimental studies carried out, it was discovered that the virgin soil was acidic with pH of 4.41. Based on particle size analysis, the soils were classified as clay soil with intermediate plasticity. Lime was tested for Initial Consumption of Lime (ICL) obtained at 2% and pH of 17.8, with a plasticity index of 21% for neat soil sample. Upon stabilization; the lowest plasticity index of 15.2% was obtained for the soil treated with 4% lime and 3% Renolith. The compaction characteristics of the neat sample were 1667kg/m3 and OMC of 18.7%. After stabilization, the highest MDD was 1788kg/m3 for the soil treated with 4% lime and 3% Renolith. The CBR value for unstabilized soil sample was obtained as 11%. This was characterised as G10 according to Ministry of Works and Transport manual (2018). After stabilization; the highest soaked CBR was 75% achieved by soil treated with 4% lime and 3% Renolith. The unconfined compressive test result for the untreated sample after stabilization improved from 0.74MPa to 3.73MPa for the soil treated with 4% lime and 3% Renolith, quite similarly the soaked UCS value improved from 0.57MPa for to a maximum of 2.09MPa for soil treated with 4% lime and 3% Renolith after 7 days. After stabilization, the properties of the soil were greatly improved, the use of 3% Renolith by weight of lime and 4% lime by weight of soil sample has been recommended as the most effective dosage in the improvement of soil to a sub-base material.