1. Introduction
In the field of civil engineering, various methods are adopted to
improve the geotechnical properties of soils in order to meet the
requirements for stability and maintenance cost reduction. Clayey soil
stabilization by various additives may be one of these methods, because
of the substitution of inappropriate soils by adequate ones has become
increasingly expensive and ecologically unsafe. Besides that,
stabilization by cement is not preferable due to its growing cost and
environmental concerns related to its production (Al-Swaidani et al.,
2016). Luting materials such as lime have been successfully employed in
the geotechnical engineering discipline for soil stabilization purpose
and mechanical properties improvement, especially for clayey and silty
soils. Lime is widely used in civil engineering applications such as
road construction, embankments, foundation slabs and piles (Al Rawas and
Goosen, 2006).
The carried out studies in the literature show that the addition of lime
increased the optimum moisture content and strength, and reduce the
plasticity index and maximum dry density of the soil (Guney et al.,
2007; Croft, 1967; Ola, 1977; Rahman, 1986; George et al., 1992; Bell,
1996; Gay and Schad, 2000; Hossain et al., 2007). On the same matter,
extensive studies have been carried out on the stabilization of clayey
soils using lime (Basma and Tuncer, 1991; Kassim and Chern, 2004;
Mohamed et al., 2009; Sherwood, 1993). As investigated by Sabry (1977),
many significant engineering properties of soft soils also can be
beneficially modified by lime treatment, as lime decreases the
plasticity index, increases the workability and shrinkage limit, reduces
shrinkage cracking, eliminates almost all swelling problems, and
increases soil strength.
In another way, several researchers (Al-Rawas et al., 2005; Goswami and
Singh, 2005; Rahman, 1986; Muntohar and Hantoro, 2000; Attoh-Okine,
1995; Nalbantoglu, 2006; Lasledj and Al-Mukhtar, 2008; Osula, 1996; Ola
1977; Bagherpour and Choobbasti, 2003; Kavak and Akyarli, 2007; Manasseh
and Olufemi, 2008; Okagbue and Yakubu, 2000; Ansary et al., 2006) found
that in most cases, the effect of lime is more or less instantaneous on
the plasticity properties of the clayey soils.
On shear strength characteristics, hence in some studies (Lin et al.,
2007; Chen and Lin, 2009) postulated that the observed shear failure
mode of stabilized soil samples with lime is similar to brittle
materials. Moreover, some researchers (Consoli et al., 2012; Calik et
al., 2014) found that the soil strength properties were greatly improved
after lime treatment. According to the study of Consoli et al. (2012 and
2014), the decrease of pores and lime volume increase are directly
responsible for the increase of soil-lime mixture strength.
This paper presents the effect of hydrated lime on the Atterberg limits,
compaction characteristics, and unconfined compressive strength of
Sulaimnai city, Northern Iraq CL soil, which classified according to the
unified soil classification system (USCS). All tests were conducted in
accordance with the ASTM standards (1990 - 2000).