Characterization of Soil A-6(11) Stabilized Using Three Different Types of Nigerian Produced Portland Cement Independently Isaac Akiije Department of Civil and Environmental Engineering Faculty of Engineering, University of Lagos, Akoka, Yaba Lagos, Nigeria Abstract - In this paper, two different types of normal 42.5N and one rapid 42.5R Portland cements that are being produced in Nigeria have been used to stabilize soil A-6(11) and characterized for optimization purpose. The three Portland cement are tagged 42.5Np, 42.5Ns and 42.5Rx for the purpose of clarity and identification. The natural laterite soil was obtained from a borrow pit at Abule-Ijoko in Ogun State of Nigeria. Material composition tests showed that the major components in the cements 42.5Np, 42.5Ns and 42.5Rx are CaO, SiO 2 and Al 2 O 3 while that of the soil are SiO 2 and Al 2 O 3 . Laboratory experiments employed on the laterite included soil classification for highway purposes and also its stabilization at 2%, 4%, 6%, 8%, 10%, 12% and 14% using the three types of cement individually. Other laboratory experiments performed individually included optimum moisture content (OMC), maximum dry density (MDD), California Bearing Ratio (CBR), unconfined compressive strength (UCS) and permeability upon the natural and the stabilized soil. The classification results showed that the percent passing sieves 4.750 mm, 2.000 mm, 0.425 mm and 0.075 mm respectively by grain size analysis of A- 6(11) are 100%, 98%, 71% and 56%. The respective results of the liquid limit, plastic limit and plasticity index for soil A-6(11) are 40, 20 and 20. The OMC of the soil specimen at natural and at the increasing cement stabilization of same are reducing while the related MDD are increasing. At natural state and for the strategic percent increase of cement content for the soil specimen, both unsoaked and soaked CBR, uncured and cured UCS values are increasing while the permeability amounts are reducing. The significance of this study is that for each type of stabilization at 2% cement content the unconfined compressive strength satisfied subbase requirement whilst at 4% of same satisfied maximum and minimum standard requirements respectively for subbase and road base. The justification for this study is that at 6% cement content of stabilization, the three different types of cement satisfied possible design values of cured UCS for road base economically in spite soil being A-6(11) clayey soil. Keywords: Laterite; Borrow; Subbase; Base; Highway; Nigeria 1. INTRODUCTION Oftentimes different cement types’ with equal content in percentages of stabilized soil sample individually to attain specified strength for stable subbase or road base is not the same. Akiije [1] experimented in the laboratory upon optimizing the characteristics of A-1-b(0) stone fragments gravely sandy soil, A-2-7(0) clayey gravely sandy, A-4(3) silty soil and A-5(10) silty soil individually using Powermax Portland cement of grade 42.5N as to their pertinent stabilization for highway subbase. It was concluded that of the four soils experimented upon only the stabilized A-1-a(0) with Powermax cement stabilization attained UCS value of 840 kN/m² at 6% that satisfied the minimum strength requirement of 750 kN/m² for highway subbase. Achampong et al.[2] reported that cement stabilization mechanism is mainly controlled by hydrolysis and hydration which affect physical properties of soil-cement including soil type (particle size distribution, grain shape, mineralogy); proportion of soil; cementation material; water content; quantity of cement; degree of mixing; time of curing; and density of the of the compacted mixture. Here hydration means addition of water and cement while hydrolysis is the reaction process of both. Khan [3] considered cement stabilization into two categories which are normal soil-cement and plastic soil- cement. He claimed that normal soil-cement consists of 5% to 14% cement content by volume and with sufficient water used for hydration and workability requirement whilst ample to produce a material that is hard, durable weather resistant, strong and used for stabilizing sandy and other low plasticity soils. Khan [3] also stated that the plastic soil-cement consists of 5% to 14% of cement by volume with more water to have wet consistency similar to that of plastering mortar at the time of placement which are useful for water proof lining for canals, reservoirs and protection for steep slopes against water erosion. Husna [4] considered the possible initial estimated cement requirements for various soils using the Unified System and proclaimed initial estimated cement content percent dry weight for highway subbase and base stabilization as in Table 1. Also, Das [5] identified symbols in use by the Unified System for soils description as in Table 2. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV6IS010087 Vol. 6 Issue 01, January-2017 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : www.ijert.org 278