Amin Eisazadeh

Stabilization of tropical kaolin soil with phosphoric acid and lime

Studies on the chemically stabilized soils have shown that the effectiveness of treatment is largely dependent on soil’s natural environment. In tropical kaolin soils, phosphoric acid may be used as an alternative to traditional alkaline stabilizers for improving soil properties. This research was carried out in an effort to identify the time-dependent soil-stabilizer reactions. Data for the study of characterization of treated samples were obtained from X-ray diffractometry, energy dispersive X-ray spectrometry, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and leaching analysis. Based on the collected data, the kaolinite mineral with pH-dependent structural properties showed slightly different behavior both in basic and in acidic mediums. Also, it was found that the chemical stabilizers preferentially attacked the alumina surface of the clay particles. Therefore, it was rational to suggest that with respect to lime and phosphoric acid treatment, aluminate hydrate compounds are more likely to be formed.

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.

Cation Exchange Capacity Of a Quartz-Rich Soil in an Acidic and Basic Environment

In this research, the time-dependent changes induced in charge characteristics of phosphoric acid and lime treated quartz-rich kaolinitic soil were investigated. Also, in order to study the relationship between the exchange capacity and the pore water chemistry, pH measurements was performed on cured samples. Based on the collected data, it was found that the pH of stabilized soils showed a tendency for reaching soil’s natural pH with increasing curing time. In addition, the increase in number of broken bonds around the edges of soil particles and also the formation of cementitious compounds that acquired negative charges contributed to achieving higher CECp values at longer curing periods. From engineering point of view, the lime treated samples revealed the highest degree of improvement with an approximately 16-fold strength increase in comparison to the natural soil over an 8 months curing period.