SOIL IMPROVEMENT ON MINING SAND USING PULVERIZED FUEL ASH (PFA) WITH LIME ADDITIVE

The state of Perak was famous of a location of tin mines long ago due to the rich of
tin contained in soil and rocks especially in Kinta Valley and harvested leaving
abandoned tin mines. Pulverized Fuel Ash (PFA) is the byproduct of a coal
burning to generate energy from power plant and this byproduct is useful in
stabilizing soil under specific condition. This project was carried out to find the
highest unconfined compressive strength from the mix between mining sand with
PF A and lime as additive. Soil improvement on mining sand could improve the
strength carried by the soil. From the experiment of this project, the optimum lime
found is 10% lime. The 10% lime then mixed with mining sand and PF A range
from 5% until 25% for 5 different percentage mixes. The mixtures then analyzed in
term of particle distribution, compaction test and unconfined compression test. For
unconfined compression test, the curing periods implemented for the sample mix
before tested and the curing periods selected are 7, 14, and 28 days. The sieve
analysis for each of the mixtures shows significant improvement on percentage of
the silt and clay that is for 3% of raw mining sand to 11% for Mix 5. The standard
proctor test conducted shows that the highest maximum dry density could be
achieved at 2.1851 Mg/m3 at Mix 2. The Undrained Shear Strength shows
significant increase based on curing period and the increasing percentage of PF A.
The highest undrained shear strength occurs at Mix 5 for 28 days curing period that
is at 6.675 MPa. This shows that for more percentage of PFA, the strength is
increased. The curing period of the mixtures also affect the undrained shear
strength. For longer curing period, the undrained shear strength is higher as shown
for Mix 3 that is at 305.53 kPa for 7 days while at 3.935 MPa for 28 days of
cunng.