Laboratory Compaction Method of Soft Clay and Natural Plant Fiber/Shell Mixtures

Abstract

One method of soil stabilization is to mix the soil with natural materials such as fibers or shells from plants. Generally, the samples are compacted in a laboratory by mean of Standard and Modified Proctor Compaction tests. The results of compaction are the relationship between water content and density, as indicated by the dry unit weight of the samples. In principle, this compaction process reduces the pore space filled with air in the soil. In this condition, soil is not saturated with water. The method cannot be used to compact soils that are in water-saturated conditions such as soft clay soils which are commonly found in wetland areas. This paper focuses on describing methods for compacting soft clay mixed with additional materials such as fibers and shells from plants. Two steps must be taken to compact samples of mixed soil and natural material. Firstly, determining the percentage of the mixture at which the sample can be compacted, and secondly, determining the optimum fiber/shell content to produce maximum density. The equipment and energy used are the same as the Proctor standard compaction test. Examples of calculations and results obtained for each material (i.e., empty fruit bunches and oil palm shells) are presented and discussed in the paper. Compaction procedures in the laboratory for the mixture of soft clay and other materials are also suggested in the paper.