International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 7 (2017) pp. 1365-1370 © Research India Publications. http://www.ripublication.com 1365 The Influence of Geopolymer for Laterite Soil with Different Compaction Effort as a Soil Liner Dr. Mazidah Mukri Senior Lecturer, Faculty of Civil Engineering Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. Nik Nurul Syuhada Nik Ab Aziz Postgraduate Student, Faculty of Civil Engineering Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. Abstract Modern landfills are designed to prevent liquid from leaching out and entering the environment. However, if not properly managed, the leachate is at risk for mixing with groundwater near the site, which can have negative effects to the human and environment. Lining system is the most important part in a landfill area. The purpose of lining system is to minimize leachate egress and prevent ground pollution. The typical forms of lining system are clay mineral liners, geomembrane liners and bentonite enriched soil liner. In designing soil liner, it is important to compact it properly to achieve low hydraulic conductivity and high strength of soil. In this study, laterite soil is used as a soil liner which were stabilized by adding different percentage of geopolymer. Geopolymer is a material that can easily react with water which results into a powerful compaction aid giving a higher density for the same compaction effort. Hence, geopolymer is choose to mix with laterite soil. Different percentage of geopolymer were used which are 5%, 10%, 15% and 20%. This research was carried out in an attempt to see the difference of compaction parameters between two types of compaction effort for laterite soil mix with geopolymer. The outcome of this study give a positive results due to the potential of geopolymer to fulfill spaces that exist between soil particles. It is also found that geopolymer give influences to the resistance properties, hydraulic conductivity and the strength of soil. Keywords: Laterite soil, geopolymer, compaction effort, optimum moisture content, maximum dry density, soil liner INTRODUCTION Soil liners are commonly used in the base of waste containment facilities. It has been used for many years as engineered hydraulic barriers for waste containment facilities. A low hydraulic conductivity is the key parameter in the design of liner to prevent the downward migration of contaminants into aquifers. Besides that, [1] exposed that a landfill liner should have low hydraulic conductivity, be resistant to shrinkage cracking and have suitable mechanical properties for structural integrity during construction and operation. According to [2], from their studies suggest proper soil set of values for basic soil properties in order to achieve a hydraulic conductivity lower than 10 -7 cm/sec. Fine grained soils are normally used as a barrier primarily because their particle size is small enough to limit the flow of fluids. Compacted soil liners, usually 0.6 m to 3 m thick, consist of natural soil which is recompacted in the field to obtain the desired hydraulic strength properties. Good engineering practice and quality assurance programs can result in good quality and low hydraulic conductivity soil liners [3]. The hydraulic conductivity of compacted soil liners depends on the soil mineralogy and the manner of placement of the liner. Examples of soil liners used in liner and cover systems are shown in Figure 1. Figure 1: Examples of typical modern landfill (Source: [3]) Compaction Compaction is defined as the reduction in soil void ratio by expulsion of air from the voids. Compaction occurs instantly with application of a force. Because compaction involves reducing the void ratio without changing the moisture content, the degree of saturation will increase [4]. Usually, the compactability of soil can be used as an example how moisture content, strength and management can interact. The wet soil has low resistance to structural change because it has a lower strength compare to dry soil. This is showed by the critical moisture content curve. For a given compaction force, the compaction effect increases as water content increases until to a point where the soil become so wet that the compaction will drops off. The critical moisture content for compaction occurs at the peak of the curve. There are a lot of factors that can affect the critical moisture content of the soil including soil texture and organic content of the soil.