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Clayey soil generally possesses volumetric changes when subjected to change in moisture
content because of the seasonal water fluctuations. Also, low strength and high compressibility
habits of most clays can cause severe damage to civil engineering structures. Therefore, these
type of soil must be treated before commencing the construction operation. Various methods
are available to improve the engineering properties of these soils such as densification,
reinforcement, chemical stabilization and techniques of pore water pressure reduction. The
chemical stabilization of clays using fly ash is one of the best alternative as it improves various
engineering properties of soil such as maximum dry density and unconfined compressive

With addition of fly-ash in the soil, the index properties of soil are found to be improved. It is
found that the optimum moisture content decreases while maximum dry density increases with
addition of fly ash. The unconfined compressive strength of the soils increases with the addition
of fly ash content. This paper presents the effective use of fly ash in improving the engineering
properties of clayey soil. A series of tests were conducted on clayey soil treated with fly-ash
alone (i.e. 2%, 4%, 6%, 8% and 10%). From the test results, it was observed that with the
increase in fly ash content the Maximum Dry Density (MDD) increased up to 5.81% at 6% fly
ash content. The optimum fly ash content was determined based on Standard Proctor test and
Unconfined Compressive Strength (UCS) test results. The maximum UCS value was observed
at 6% of fly-ash content. The increase in UCS at 6% fly ash content was 10.9%.The use of fly
ash as the stabilizer with soil is a cost-effective and environment-friendly technique to make
the soil mixes strong.

In to make the soil clay in our study become strong we use fly-ash as a material. Fly-ash is a
product of coal fired electric power generation facilities, it have a little cementitious properties
compared to cement and lime. Most of the fly-ash belong to secondary binders, these binder
cannot produce the desired effect on their own. However, in the presence of a small amount of
activator, it can react chemically to form cementitious compound that contributes to improved
strength of soft soil. Fly-ash are cheaper, readily available and most importanting
environmental friendly. These are two main classes of fly ashes, class C and class F
(Bhuvaneshwari et al, 2005, FM 5-410). Class C fly ashes are produced from burning
subbituminous coal, it has high cementing properties because of high content of free Cao. Class
C from lignite has the highest CaO (above 30%) resulting in self cementing characteristics
(FM5-410). Class F fly-ash are produced by burning anthracite and bituminous coal, it has low
self-cementing properties due to limited.

soil fly-ash stabilization has the following limitations (White.Figure 1: Effect of addition of the lime on plasticity properties of London clay (Sherwood 1993) Amount of free CaO available flocculation of clay minerals and thus require addition of activator such as cement or lime. . However. 2005). The reduction of swell potential achieved in fly-ash treated soil relates to mechanical bonding rather than ionic exchange with clay minerals (Mickiewicz and Ferguson. 2005).

Sulfur contents can form expansive minerals in soil fly-ash mixture. . 2. . therefore dewatering may be required. Environment and Natural resources engineering Division of Mining and Geotechnical Lulea University of Technology Lulea. . which reduces the long term durability and strength. production of which entails energy consumption and CO2 emissions. Soil fly-ash mixture cured below zero and then soaked in water are highly susceptible to slaking and strength loss. Saving of scare of natural resources. . Anita Saika.Tinku Kalita. . Saving of space for disposal. Sweden” Lulea 2012. Reference 1. Protection of environment. Bhaskarjyoti Das “Effect of Fly-ash on strength Behaviour Clayey Soil” International Research Journal of Engineering and Technology (IRJET).Gregory Paul Makusa “Soil Stabilization Method and Material” Department of Civil. . as in construction it can partly replace cement. Soil also can be stabilized shall have less moisture content. Issue 07 July 2017. Volume:04.Advantages using fly-ash .