ORCID Identifier(s)

ORCID 0009-0006-2828-7068

Graduation Semester and Year

Fall 2024

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Prof. Dr. Xinbao Yu

Second Advisor

Prof. Dr. Laureano R. Hoyos

Third Advisor

Dr. Habib Ahmari

Abstract

The swelling and shrinkage of the expansive soil as a response to moisture change is one of the significant challenges posed to infrastructure projects. The significant economic damage that is caused by the expansive soil, as well as its abundance in nature, has prompted various scientists and engineers all around the world to actively search for new and improved methods for stabilizing it. Various traditional methods, such as lime and cement treatment, have been used extensively to stabilize expansive soils and mitigate their harmful effects on the infrastructure. Although these methods are quite often effective and various studies have been done to show the effectiveness of such treatment methods, there are various limitations to such methods, such as they are detrimental to the environment and need dry conditions to be applied in the field. Furthermore, soils rich in sulfate content are susceptible to sulfate attack, which can lead to sulfate-induced heave, further compromising the soils' stability.

Given all these limitations of the traditional methods of soil stabilization, crystallizing hydrophobic materials such as CHEM-CRETE DC soil stabilizer are needed to stabilize expansive soil, as it is not only environmentally friendly but also moisture tolerant, which means they can be used even when the field condition is moist. Therefore, the CHEM-CRETE DC soil stabilizer emerges as a promising alternative to the traditional methods of stabilization. Hence, the CHEM-CRETE DC soil stabilizer is used in this study as it addresses most of the problems underlying the use of traditional soil stabilizers, such as lime and cement. By inducing the hydrophobicity in soil, CHEM-CRETE DC soil stabilizer tries to stop water from getting into the soil and making it swell. This makes the expansive soil more stable and lessens any changes in its volumetric change. In addition to CHEM-CRETE DC soil stabilizer, a well-established hydrophobic chemical named dimethyldichlorosilane (DMDCS, ≥99.5%) that has been previously studied by researchers for its effectiveness in inducing hydrophobic behavior in soils has also been used in this study for further analysis on stabilization of expansive soil by inducing hydrophobic nature in soil.

This study mainly focuses on studying the efficiency of the CHEM-CRETE DC soil stabilizer and DMDCS in stabilizing the expansive soil while also studying the change in the soil’s strength parameters. Different types of soil were used in the study, including natural soils like Burleson soil and Irving clay and mixtures of bentonite and sand prepared in the lab. Various ratios of bentonite and sand were tested, and 15 % Bentonite and 85% Sand were taken as the best ratio for the test based on the 10-day swelling result. A thorough experimental plan was prepared and followed to investigate the effect of CHEM-CRETE DC soil stabilizer and DMDCS on the physical and mechanical properties of the soil. Those tests included the Atterberg limits test, bar linear shrinkage test, sieve analysis, hydrometer test, standard proctor test, one-dimensional test, unconfined compressive strength (UCS) test, direct shear test, scanning electron microscope imaging (SEM), and contact angle test. The results were analyzed to determine the influence of the chemical on soil properties before and after the treatment.

Based on tests done on the Burleson soil, the swell potential decreased by 77.27% after the soil was treated with a CHEM-CRETE DC soil stabilizer. The plasticity index of the Burleson soil decreased by 53.27%, indicating a reduction in the soil’s affinity toward the water and an increase in hydrophobicity because of the treatment. Also, the standard proctor test result showed that the maximum dry density of the Burleson soil remained constant, but there was a decrease in its optimum moisture content. The unconfined compressive strength (UCS) test of the Burleson soil sample, prepared at 95% of the maximum dry density at optimum moisture content, further confirmed the increase in the strength of the treated soil. This increase in unconfined compressive strength was dependent on the curing time, as an increase in curing time also led to an increase in the UCS value.

The swell potential of the Bentonite and Sand (15:85) mixture was reduced to zero for 10 10-day one-dimensional swell tests after being treated with a CHEM-CRETE DC soil stabilizer. The maximum dry density of the soil sample increased by 5.4%, whereas the optimum moisture content of the soil mixture decreased by 11.6%. These changes and enhancements in the soil's strength and workability confirm the suitability of CHEM-CRETE DC soil stabilizer as an environmentally friendly method for stabilizing expansive soil. When a bar linear shrinkage test was conducted on the soil mixture after the treatment, the linear shrinkage decreased by 63.56%. Likewise, there was a remarkable increase in the contact angle by 105.74%. The UCS test result indicates an increase in the strength of the soil mixture. For the Bentonite and Sand mixture treated with DMDCS, the contact angle value increased by 126.24%. Also, the SEM test revealed the formation of the hydrophobic film layer over the soil surface as well as the Bentonite clumping together after treatment for both the samples treated with CHEM-CRTE DC SOIL STABILIZER and DMDCS.

Irving clay's ability to swell was cut by 58.46% after being treated with the optimum amount of CHEM-CRETE DC soil stabilizer, which is 10% by weight. The maximum dry density of the soil sample remained constant, but its optimum moisture content was reduced by 9.8%. The plasticity index of the Irving clay decreased by 40.6%, further supporting the increase in hydrophobicity and the effective stabilization of the expansive soil. The bar linear shrinkage also decreased by 63.55%, whereas the contact angle increased from 0 to 115.26. Likewise, when the soil sample was treated with DMDCS at optimum concentration, the contact angle of the soil reached 121.81 (>90), further supporting the claim of the formation of the hydrophobic layer in the soil.

In conclusion, this study provides a comprehensive evaluation of hydrophobic chemicals such as the CHEM-CRETE DC soil stabilizer and DMDCS’s influence on expansive soils. It further contributes to the growing body of research on hydrophobic soil stabilization techniques. The results show the hydrophobic property-inducing materials' potential for stabilizing expansive soil by making it more hydrophobic. Future research should be done to determine the long-term durability of soil treated with a hydrophobic chemical soil stabilizer. Also, real-world tests should be conducted and compared with other expansive soil stabilizers to refine their use across diverse geotechnical applications. In doing so, the hydrophobic soil stabilizer could be more effectively positioned as a new and robust solution for addressing the challenges posed by expansive soils so that safer and more sustainable infrastructure could be built over it.

Keywords

Expansive Soil, Hydrophobic Treatment, Soil Stabilzation, Sustainability, Geotechnical Properties

Disciplines

Civil Engineering | Construction Engineering and Management | Environmental Engineering | Geological Engineering | Geotechnical Engineering | Transportation Engineering

License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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Available for download on Friday, January 02, 2026

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