Nima Latifi

Effect of magnesium chloride solution on the physico-chemical characteristics of tropical peat

Abstract The stabilization of soils with additives is a chemical method that can be used to improve soils with weak engineering properties. Although the effects of non-traditional additives on the geotechnical properties of tropical soils have been subject of investigation in recent years, the effects of magnesium chloride (MgCl2) on the macro- and micro-structural characteristics of peat soil have not been fully studied. This study investigates the effect of MgCl2 on the physico-chemical characteristics of tropical peat. Unconfined compression strength tests were performed as an index of soil improvement in treated samples. In addition, the micro-structural characteristics of untreated and treated peat were investigated using various spectroscopic and microscopic techniques such as X-ray diffractometry, energy-dispersive X-ray spectrometry, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer, Emmett, and Teller surface area analysis. From an engineering point of view, the results indicated that the strength of MgCl2-stabilized peat improved significantly. The degree of improvement was approximately six times stronger than untreated peat, after a 7-day curing period. Additionally, the micro-structural study revealed that the stabilization process led to a few changes in the mineralogical, morphological, and molecular characteristics of the selected peat. The pores of the peat were filled by newly formed crystalline compounds known as magnesium aluminate hydrate (M–A–H).

Strength behavior and microstructural characteristics of tropical laterite soil treated with sodium silicate-based liquid stabilizer

Although the effects of nontraditional stabilizers on the geotechnical properties of tropical soils has been the issue of investigation in recent years, the micro-structural characteristics of nontraditional soil additives and in particular selected additive (TX-85) have not been fully studied. Nontraditional soil stabilization additives are widely used for stabilizing marginal materials. These additives are low-cost alternatives to traditional construction materials and have different compositions. They also differ from one another while interacting with soil. In line with that, it was the objective of this research to investigate the strength properties and physicochemical mechanisms related to tropical laterite soil mixed with the liquid stabilizer TX-85. Macro-structure study, i.e., compaction, and unconfined compression strength test were used to assess the engineering and shear properties of the stabilized laterite soil. In addition, the possible mechanisms that contributed to the stabilization process were discussed using various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry, scanning electron microscopy, and Fourier transform infrared spectroscopy. From engineering point of view, the results indicated that the strength of TX-85 stabilized laterite soil improved significantly. The degree of improvement was approximately four times stronger than natural soil after a 7-day curing period. The XRD showed no crystalline products (gel form). Moreover, weathering effects were obvious in TX-85 treated samples in most of clay minerals’ peak intensities. These effects were reduced especially for kaolinite mineral inside the soil with curing time.

Analysis of strength development in non-traditional liquid additive-stabilized laterite soil from macro- and micro-structural considerations

AbstractThe stabilization of soils with additives is a chemically modified method that can be used to improve soils with weak engineering properties. It has been well established that the size, shape, and arrangement of soil particles will affect the treatment process of natural soil with stabilizers. Also, the degree of enhancement is dependent on the morphology of the new formed products that bond the soil particles together. In this paper, unconfined compressive strength (UCS) test was performed as an index of soil improvement on liquid-stabilized (TX-85) mix designs. The time-dependent change in shear properties and compressibility behavior of treated soil was also studied using standard direct shear and consolidation tests. To better understand the structure and surface morphology of treated particles, FESEM, N2-BET and particle size distribution analysis were performed on soil-stabilizer matrix. From engineering point of view, the UCS results indicated that the degree of improvement for TX-85-stabilized laterite soil was approximately four times greater than the natural soil in a 7-day curing time period. Also, increased compressibility resistance of treated samples with curing time was evident. Based on the results, it was found that the stabilization process modifies the porous network of laterite soil. In addition, new white layers of reaction products were formed on the surface of clay particles.

Improvement of problematic soils with biopolymer-an environmentally friendly soil stabilizer

AbstractProblematic soils with high compressibility and low shear strength are often treated with traditional chemical stabilizing additives such as cement and lime to improve their engineering pro...

Sustainable Improvement of Tropical Residual Soil Using an Environmentally Friendly Additive

Many tropical residual laterites have relatively poor engineering properties due to the significant percentage of fine-grained soil particles that they contain, which are formed by the soil weathering process. The widespread presence of laterite soils in tropical regions often requires that some form of soil improvement be performed to allow for their use in various civil engineering applications, such as for road base or subbase construction. One of the most commonly utilized stabilization techniques for laterite soils is the application of additives that chemically react with the minerals that are present in soil to enhance its overall strength; effective soil stabilization can allow for the use of site-specific soils, and can consequently result in significant cost savings for a given project. With an increasing focus on the use of more environmentally friendly and sustainable materials in the built and natural environments, there is an emerging interest in eco-friendly additives that are an alternative to traditional chemical stabilizers. The current study examines the viability of xanthan gum as an environmentally friendly stabilizer that can improve the engineering properties of tropical residual laterite soil. Unconfined compressive strength (UCS) tests, standard direct shear tests, Brunauer, Emmett, and Teller (N2-BET) surface area analysis tests and field emission scanning electron microscopy (FESEM) tests were used to investigate the effectiveness of xanthan gum for stabilization of a tropical laterite soil. The UCS test results showed that addition of 1.5% xanthan gum by weight yielded optimum stabilization, increasing the unconfined compressive strength of the laterite soil noticeably. Similarly, direct shear testing of 1.5% xanthan gum stabilized laterite specimens showed increasing Mohr–Coulomb shear strength parameters with increases in curing time. From the FESEM results, it was observed that the stabilization process modified the pore-network morphology of the laterite soil, while also forming new white layers on the surface of the clay particles. Analysis of the test results indicated that xanthan gum stabilization was effective for use on a tropical residual laterite soil, providing an eco-friendly and sustainable alternative to traditional soil stabilization additives such as cement or lime.

Xanthan gum biopolymer: an eco-friendly additive for stabilization of tropical organic peat

Biogeotechnology is a recently established branch of geotechnical engineering, associated with the practical uses of microbiological techniques to improve the engineering properties of geomaterials. This study explores the utility of xanthan gum, an eco-friendly biopolymer obtained from microbial sources, for stabilization of tropical organic peat, using a series of macroscale and microscale test approaches. At the macroscale, the shear strength characteristics of both untreated and stabilized peat were evaluated using unconfined compression strength (UCS) and standard direct shear tests. Microscopic techniques, including field emission scanning electron microscopy (FESEM), Brunauer, Emmett, and Teller (N2-BET) surface area analysis, and particle size analysis, were also utilized to examine changes in the microstructural characteristics of stabilized peat that are caused by the chemical reaction that occurs between the xanthan gum and peat particles. UCS test results showed that the xanthan gum stabilization significantly improved the shear strength of the peat in its natural condition, with the 28-day strength of the stabilized peat being six times higher than the strength of the untreated peat. Microstructural analysis showed that the morphological characteristics of the peat are changed due to the chemical reaction that occurs during the curing process, as indicated by the FESEM results. Over time, formation of cementitious products was clearly observed, which welded peat particles and filled the pores in the soil structure, yielding a denser soil fabric with less pore volume and stronger attractive forces. From the testing that was performed, xanthan gum stabilization is recommended for peat as an eco-friendly and sustainable alternative to traditional soil stabilization additives such as cement or lime.

Sustainable Improvement of Clays Using Low-Carbon Nontraditional Additive

Nontraditional low-carbon additives are widely used in the sustainable treatment of problematic soils for construction and pavement materials. This study investigated the mechanical and microstructural properties of white kaolin (low strength clay) and green bentonite (high swelling clay) treated with a low-carbon sodium silicate-based liquid additive. The mechanical tests included unconfined compressive strength (UCS), direct shear and one-dimensional compression tests. Microscale assessments, including a field emission scanning electron microscopic (FESEM) test, nitrogen-based Brunauer, Emmett, and Teller (N2-BET) surface area analysis and particle size analysis (PSA), were performed on the treated specimens to investigate the modification of soil structure, including soil fabric and interparticle forces. The performance of the proposed additive is demonstrated by the improvement of shear strength and compressibility of both tested soils. The optimum additive content was found to be 6%, and a significant improvement occurred in the first 7 days of curing. The mechanical property improvement is attributed to the formation of cementitious products and, subsequently, the modification of the soil structure. These cementitious products filled the pores and bonded the soil particles, resulting in an increase in interparticle forces. The sodium silicate-based additive can offer a low-carbon alternative to traditional additives such as cement and lime, which is significant from the engineering and environmental perspectives.

Stabilization of Marine Clay by Biomass Silica (Non-Traditional) Stabilizers

The presence of marine clay in Iskandar Malaysia Region, Nusajaya had caused expensive solutions in the construction of structures and roads. Alternatively, soil treatment is suggested to increase the strength of the unsuitable material to meet the constructions requirement for foundation and also to achieve the specifications for development work. In this study, a series of laboratory test has been conducted to determine the potential of Biomass Silica (BS), one of the commercial brands namely “SH-85” to stabilize marine clay to form the basis of a strong, reliable land for construction of roads and building. Testing program involves obtaining specimens of marine clays from various locations at Iskandar Malaysia Region, followed by laboratory tests to determine the Atterberg limits and Unconfined Compressive Strength (UCS) for treated and untreated of marine clay soils. The proportions of BS added were 3, 6, 9, 12 and 15% and tested at 0, 3, 7 and 28 days curing periods. The results shows that the Plasticity Index (PI) was reduce with increment of BS content. While, an addition of BS content increase in strength treated soils 60 times more than untreated soils, which is gain in early 7 curing days period. This finding indicates the BS is a suitable stabilizer for the marine clay to become strong foundation for construction of road and building.

Strength and morphological characteristics of organic soil stabilized with magnesium chloride

Organic soil causes major problems in infrastructure development. It has high compressibility and low shear strength, and requires chemical stabilization if it is to be a sustainable geomaterial. This research investigated the strength and microstructural properties of organic soil stabilized with magnesium chloride (MgCl2). Unconfined compressive strength tests were undertaken to assess shear strength properties, and microstructural changes were monitored via field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectrometry (EDAX). The results confirm that MgCl2 improves the compressive strength of organic soil. The strength of MgCl2-stabilized organic soil is increased to around 3 – 5 times that of untreated soil during the first 7 days of curing. FESEM results show that the porosity of organic soil is filled by a new cementitious compound, identified as magnesium silicate hydrate (M-S-H).

Stabilization of Tropical Peat Using Liquid Polymer

The technology of chemically improvement of soil properties is a widely accepted approach. It is also economically viable to increase the strength of soil as well as to limit water absorption, control soil erosion and soil settlement. Encountered extensively in wetlands, fibrous peat is considered as problematic organic soil because it exhibits low compressive strength. It is generally estimated that there are around 30 million hectares of tropical land covered with highly organic soil throughout the world, out of which about 3 million hectares lie in Malaysia. The present study aimed to investigate the effect of liquid polymer as a non-traditional soil additive which namely as SS299 in peat improvement. The influence of different concentration of selected additive (1%, 2%, 3%, 4% and 5%) were investigated on compressive strength improvement of unsoaked and soaked tropical peat samples by using unconfined compressive strength (UCS) tests. In addition, the morphology changes of treated samples were assess using field emission scanning electron microscopic (FESEM) tests. The results indicated that the SS299 soil additive is able to significantly increase the unconfined compression strength of selected peat.