Evaluation of Contributing Factors on Strength Development of Lime Stabilized Artificial Organic Soils Using Statistical Design of Experiment Approach

Abstract

Lime is widely used as chemical stabilizer in soft soil stabilization. However, lime is reported to be less effective when dealing with organic soil. It is believed that the organic matter in the soil will retard the pozzolar~ic reaction which is responsible for strength enhancement. The heterogeneity nature of the organic matter in the soil makes the study complicated and reduced the repeatability of the test results. Hence, artificial organic soil with known organic matter and content are preferred by researchers when repeatability of the test results are required in determining the influential effect of each contribution factor. Various factors such as additive contents, effect of aging (curing periods), curing temperature, density of materials and moisture content are reported by previous researchers as the potential contributing factors towards the strength development. It is believed that the interaction of the factors also will contribute to the strength enhancement. Hence, this study is carried out to evaluate the contributing factors and its interactions on strength development of artificial organic soils with ltnown type and contents of organic matter. Statistical design of experiment (DOE) approach was utilized to evaluate the factors and its interaction on the strength development of lime stabilized artificial organic soils by using commercial statistics package. Three main factors were investigated: effect of organic content, effect of curing periods, and effect of additive, while other factors namely curing temperature, molding water content, types of compaction and compactive effort were keep constant through controlled experiments. Processed kaolin (inorganic material) is mixed with humic acid (organic matter) to simulate the organic soil which comprised of inorganic soil and organic matter. The density of the soil specimen and its moisture content were recorded before and after the curing process. General Linear Model (GLM) was utilized to determine the significance of the main factors, two-factor interactions, and three factor interactions. The significance factors and interactions were utilized in multiple regression analysis to develop the strength prediction model which can be utilized to predict the strength of stabilized materials within the inference space defined by the experiment.

Strength characteristics of artificial organic soils stabilized with copolymer stabilizer

“…However, the unconfined compressive strength of the K7HA3 is the highest and followed by K5HA5 and pure kaolin grade S300. The findings agreed well with the previous study [23,24] in which the moisture content and density of specimens were found not to be statistically significant with the strength of stabilized soil. Figure 4 shows the experimental results on the effect of percentages of VAE copolymer emulsion on the unconfined compressive strength (UCS) of soils.…”

“…On the other hand, it is found that the UCS of K7HA3 is greater than K5HA5. This statement can be supported by the result of the previous research which showed that at low organic contents the soil particles tend to aggregate, whereas at higher organic contents the soil particles tend to disperse [23]. Also, the organic particles are stiff when compressed and act as rigid particles when dry, but when they absorb water, they become soft and sponge-like.…”