Felix Ngee Leh Ling

Size Distribution Analysis of Kaolin Using Laser Diffraction Technique

Kaolin is widely used in ceramic, paper, and pharmaceutical industries. The suitability use of kaolin in industries will depend on its physical and chemical properties. The physical and chemical composition of Kaolin is dependent on its geological origin, geographic source and processing. Processed kaolin available in the market is normally graded by the manufacturer based on its physical and chemical composition. This paper is focused on the size distribution analysis of nine types/batches of processed kaolin and one raw kaolin soil by using laser diffraction technique (based on Fraunhofer diffraction theory) in accordance to BS ISO 13320:2009. The laser diffraction technique is widely used in the powder industries in determining the particle size distribution because of its simplicity and its repeatability. All the specimens were pre-sieved with a sieve of 2mm aperture size. The effective size, uniformity coefficient and coefficient of curvature of the material were also calculated to facilitate the size distribution analysis. The findings of this paper are expected to benefit industries in which size the distribution of the kaolin will directly or indirectly contribute to its suitability use.

Effect of Humic Acid on Geochemistry Properties of Kaolin

Organic soil is always known as problematic soil because of its engineering properties are inferior from other soft soils and/or because its behaviour may deviate from traditional rules of soil behaviour which makes it difficult to predict and design. Considerable research has been carried out over the years on organic soils, particularly peat soil which consists of various components of organic matter but the effect of particular organic matter is less reported. Hence, this study is carried out to determine the effect of humic acid (a kind of humified organic matter) on kaolin (which is widely studied). This paper addresses the influence of humic acid (30% and 50% of dry mass) on kaolins geochemistry properties namely Atterberg limits, compaction, specific gravity and Loss on Ignition (LOI). The findings of the study showed that the contents of humic acid had altered the behaviour of kaolin. The loss on ignition increased linearly with the increment of humic acid. However, the specific gravity, maximum dry density and Atterberg limits decreased with addition of humic acid. Atterberg limits decreased as the humic acid increased is believed to be due to the nature of humic acid which precipitated under acidic environment.

Stabilization of Artificial Organic Soil at Room Temperature using Blended Lime Zeolite

Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.

Reaction Products of Lime Zeolite Stabilized Kaolin Humic Acid

Lime, a traditional calcium based stabilizer, had been widely used in chemical stabilization to improve the strength of soil. Past researches had shown that the major reaction product of lime and soil such as Calcium Silicate Hydrate (CSH) was formed abundantly under the observation of microscopic studies. However, sometimes it will be quite difficult to confirm the existence of CSH phase if solely based on its needle like structures, especially when other rod like structures will also exist. Practically, the recognition of the CSH phase by using XRD spectrum through matching with published data had speed up the process of identification. If the method is viable, then theoretically, the molecular weight ratio of silica and calcium, S/C of CSH gel is specific and can be determined based on its possible chemical compound. Hence, this study was carried out in an attempt to examine the possibility use of its S/C ratio as a quick method to confirm the existence of CSH gel. Two types of artificial organic soils were formed by admixing kaolin (inorganic matter) and humic acid (organic matter) with the ratio of 7:3 and 5:5. Four types of admixtures with different percentages ratio of lime and zeolite (a kind of pozzolan) were used to stabilize the soils. The specimens were cured at elevated temperature of 50°c in order to accelerate the development of reaction products. Field Emission Scanning Electron Microscope with attached Energy Dispersive Analyzer (FESEM-EDX) was utilized to observe and determine the existence of reaction products and its bulk chemical composition. The S/C ratio of needle like structures were determined and it is found that the S/C ratio fluctuates and varies significantly from one specimen to another. It is believed that due to the limitations of the experimental setup, the EDX analysis can only serve as semi-quantitative and act as a reference guide on the existence of element. Despite of its limitations, the EDX analysis is useful in distinguish the CSH from other structure which is physically un-identical.

Effect of train vibration on settlement of soil: A numerical analysis

The drastic development of transit system caused the influence of ground-borne vibrations induced by train on ground settlement became concern problem nowadays. The purpose of this study is to investigate soil settlement caused by train vibration. To facilitate this study, computer simulation of soil dynamic response using commercial finite element package – PLAXIS 2D was performed to simulate track-subgrade system together with dynamic train load under three different conditions. The results of simulation analysis established the facts that the soil deformation increased with raising in water level. This phenomenon happens because the increasing water level not only induced greater excess pore water pressure but also reduced stiffness of soil. Furthermore, the simulation analysis also deduced that the soil settlement was reduced by placing material with high stiffness between the subgrade and the ballast layer since material with high stiffness was able to dissipate energy efficiently due to its high bea...

Strength Development of Lime Treated Artificial Organic Soil

In over many years, considerable research has been carried out on organic soils which consists of various components of organic matter but the effect of particular organic matter is less reported. Thus, some of contributing factors for each organic matter are not fully understood yet. Hence, the aim of this study is to determine the effect of organic acid concentration on the strength of artificial organic soil. There are four types of artificial organic soil created by mixing kaolin (inorganic matter) and organic acid (a kind of humified organic matter) in different concentrations. Unconfined Compressive Strength test (UCT) was carried out for all soil samples after being cured for 7 and 28 days under room temperature and 50°C. Soil samples shows highest strength when cured for 28 days under 50°C compared to those cured under room temperature. However, when the organic acid concentration decrease, the strength increased for soil 2 after 7 and 28 days cured under room temperature and 50°C. Apart from this, soil 3 and soil 4 that were cured under room temperature shows decrease in strength when the organic acid concentration decreasing but different result shown for both samples when cured under 50°C.

Modelling of Clay Behaviour in Pile Loading Test Using One-Gravity Small-Scale Physical Model

The observations and tests under small scale in 1-gravity condition are intended to obtain a comparative behavior of a model and prototype of geotechnical case by imposing the scaling relations. Simulations to represent a related structure, sub-soil and failure mechanism need to be prepared prior to do observations in this modeling. To simulate pile loading test (PLT) on clay, the following models of: clay, pile, driving simulation and procedure of PLT based on ASTM D4410 were set-up. The PLT in reduced scale environment was then followed by performing normal practice of full scale PLT in original clay site. Load settlement curves obtained from both “pile loading test” in small and full scale simulations showed closely good agreement. Further observation and investigation on simulation of pile loading test in clay revealed that modeling the following: clay sub-soil resulted in new properties of clay, em=ep+λLn(N) which reflects stress scaling factor, N, pile size and pile driving hammer need scaling factor n and n3 respectively whereas PLT time needs time scaling factor, tp (n)0.5.

Geochemical Properties of Peat Soil in Sarawak - A Review

In geotechnical field, peat soil is defined as soil which is formed by accumulation of purely one hundred percent organic matter and which the distinction between soil and vegetative accumulation is not clear. The main objectives of this review paper are to summarize and compare the geochemical properties of peat soil in different districts of Sarawak. Case studies that have been chosen covered central of Sarawak up to the North of Sarawak. Geochemical properties of peat soil that being observed are pH, total carbon, organic matter, bulk density and the total nitrogen. Geochemical properties are found to be governed by the types of material inside the soil and also strongly correlated with the engineering properties of soil. Notably showed that the types of organic matter, namely fibre and/or humidified organic inside the soil will influence the soil porosity. The findings of the studies showed that geochemical properties of the peat soil in different districts of Sarawak is site dependent and could be affected by the different land use or land activities. The differences in land use and land activities affected the bulk density, pH and types of organic matter in the soil. The result indicated that peat soil land in different district can categorized as acidic soil because of the pH range is between 3.3-3.75. For the bulk density, the lowest value is recorded at the Dalat sago plantation site, which is 0.14 g/cm3. For the value of the total carbon, peat soil from the Laogan Bunut National Park is the lowest, 47.6%. Furthermore, total carbon is related to the soil organic matter, coincidentally the value of soil organic matter in Miri found to be the lowest which is 74.59%. Result for the total nitrogen, there are little difference between the district. Range of the total nitrogen is from 0.9% to 2.4%, Sibu site is getting the lowest value in this case.

Strength and Stiffness of Artificial Organic Soil Admixed with Lime Zeolite

Chemical stabilizers especially calcium based stabilizer, namely lime and cement had been widely used to modify and stabilize the soil. Extensive studies were carried out by researchers to improve the effectiveness and cost-benefit of stabilizers by introducing various types of blended lime and cement. Unconfined compressive test (UCT), one of the most simple and quick strength tests, is commonly used by researchers to indicate the suitability and successfulness of newly introduced stabilizer. The aim of this study is to establish the relationship and correlation of unconfined compressive strength and tangent modulus, E at 50% of unconfined compressive strength of artificial organic soil admixed with lime zeolite. Two types of artificial organic soils, which named as Type A and Type B were prepared manually by mixing commercial kaolin with humic acid powder in different percentages. The artificial organic soils were admixed with blended lime zeolite in different ratio and cured for 7, 28 and 56 days in an oven with controlled temperature of 50°c. The strength of the materials were determined by compressing the specimens using a UCT testing frame and the tangent modulus, E50 were calculated by plotting a linear slope at 50% of ultimate strength over stress-strain curve. The findings of the study showed that the strength and E50 are strongly correlated and important as the indicator of rigidity of the material as well as its capability to resist compressive load.

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

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 pozzolanic 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 known 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.