Effect of Class C Pulverized Fuel Ash on Shear Strength of Silty Sand Soil Type

The potential usage of PFA in soil stabilization has increased significantly
due to increased availability and the introduction of new environmental regulations
that encourage the use of PFA in geotechnical applications when it is
environmentally safe. The main objective for this project is to investigate the benefit
of using PFA for soil stabilization. This study covers the basic characteristics of soil
and PFA, compaction, shear strength parameters and Atterberg limit. The samples
were subjected to unconfined compression tested immediately as compacted and
after curing for 3 and 7days at temperature of 38°C to develop water contentstrength
relationship. This soil was mixed with different percentages of PFA varying
from 9% to 24% with increment of 3% by dry weight of soil. Soil samples were
collected from oil-palm plantation at Changkat Cermin while PFA were collected
from TNB Manjong. The soil sample was predominantly quartz while the PFA is
classified as Class C PFA. The mixtures between soil and PFA had increased the
compaction and shear strength behavior. The optimum dry density was achieved
when PFA content was 12%. Shear strength of the soil-PFA mixtures were increased
50% during immediate test and the greatest shear strength acquired was during 7
days of curing with PFA content of 21%. During the experiments all samples failed
with visible shear failure with angle of 60-65° and all samples became more brittle
after curing. The particles sizes of soil-PFA mixtures became more solid and contain
lesser air voids compared to the untreated soil. The bonding between these materials
indicated chemical reactions had occurred in these materials to form cementation
product. From the experiments conducted, it can be concluded that the addition of
Class C PFA has improved the engineering properties of soft soil significantly