Geotechnical and other characteristics of cement-treated low plasticity clay

The successive urban development in various parts of the world necessitated further improvement of the infrastructure accompanying the constructed facilities. Compacted finegrained soils are used in the infrastructure earthworks such as the construction embankment of roads, highways, road foundations. Fine-grained soils (especially clayey soils) consider as a problematic soil and can induce damages to roads founded on them, due to their volume changes, higher water content and/or low bearing capacity. The use of ordinary Portland cement; its components or residues; has been widely used in stabilizing cohesionless and some types of problematic soils like clayey soil. Studies conducted in this field may be classified into three main categories: use byproduct from cement production operations, direct use of cement alone or mixed with other materials, and recycling of cement as concrete waste. The use of cement byproduct, especially cement kiln dust to stabilize or improve clay soil was cover by many studies (Adeyanju & Okeke, 2019; Amadi & Osu, 2018; Miller & Azad, 2000; Naseem et al., 2019). The mixing of cement with fly ash become commonly used to reduce the amount of cement used or improve specific geotechnical properties of soil (Amu et al., 2008; Chenari et al., 2018; Khemissa & Mahamedi, 2014). Portland cement was also used with other stabilizing materials to improve the soil engineering properties. Lime is used with cement to improve the soil strength and reduce the swelling and settlement (Amu et al., 2008; Joel & Agbede, 2010; Lemaire et al., 2013; Mousavi & Leong Sing, 2015; Riaz et al., 2014; Saeed et al., 2015; Sharma et al., 2018; Umesha et al., 2009; Wei et al., 2014). Nayak & Sarvade (2012) used cement and quarry dust to improve the shear strength and hydraulic features of lithomarge clay. Ayeldeen & Kitazume (2017) utilized fiber, and liquid polymer to enhance the strength of cement-soft clay blends. The fibers and liquid polymers displayed a notable mechanically, economically and environmentally prospects to be used as an additive to cement in improving the soft clay. Also, organic soils have become the target of many studies that have addressed improving the properties of these soils by adding cement and other materials (Kalantari & Huat, 2008; Kalantari & Prasad, 2014). Moreover, Osinubi et al. (2011) used ordinary Portland cement –Locust bean waste ash mixture to enhance the engineering properties such as (UCS) and ‎California bearing ratio (CBR) for black cotton clayey soil. Crushed concrete waste, which represents the last form of cement used, has been used in many studies to improve the properties of clay soils (Abdulnafaa et al., 2019; Abstract This research work examines the utilization of cement in order to improve low plasticity clay soil. The soil samples treated with 2, 4 and 6% cement percents and cured for different curing times extended to 90 days. Laboratory investigations include unconfined compression, indirect tensile, gas permeability and microstructural tests, which were conducted on the tested samples. The soil-water retention behavior has been also investigated. The test results showed that the cement addition improved both the compressive and tensile strength properties of soil specimens. These strength properties were also increased with curing times. pH and electrical conductivity values were good indicators for the enhancement in the strengths properties. The results of micro structural tests illustrated that the natural soil specimens contain voids and the open structure. Further, these tests showed the cementation of soil grains and filling the voids among soil grains with cementing compounds. Gas permeability and soil-water retention behavior of soil specimens are strongly related to the variations in the soil structures. Further examination illustrated that in the case of low cement content, the pore size distribution (PSD) and the efficiency of gas permeability are more sensitive to curing times.