| dc.description.abstract | 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. | en_US |
