Information about PhD thesis of Postgraduate. Nguyen Huu Nam

THESIS ABSTRACT OF PHD STUDENT NGUYEN HUU NAM

The writer's name:       Nguyen Huu Nam

Supervisor:                   Dr. Ngo Anh Quan
                                       Assoc. Dr. Hoang Pho Uyen

Thesis title:                   Investigation of using pozzolan-cement and lime for improving basalt soil in waterproof tilted wall of west highlands
Branch:                         Geotechnical Engineering
Code:                            9-58-02-11
Postgraduate training unit: Vietnam Academy for Water Resourses

CONTENTS OF EXTRACT

1. The aim and object of the study of the thesis

1.1. Objectives of the study

- It is proposed to have a suitable mix of natural pozzolan, cement and lime to improve basalt soil to make inclined wall waterproofing earth dam in the Central Highlands;

- The improved soil mixture has a permeability coefficient K<10-5 cm/s, is stable in water, does not swell (shrink) and disintegrate.

1.2. Research subjects

- Research object: improve basalt soil with natural pozzolan binders, cement and lime to make inclined wall waterproofing earth dam.

- Research scope: Natural Pozzolan and small and medium earth dams in the Central Highlands.

2. Research methods used

- Overview method

- Inheritance method

- Analytical methods

- Methods of mathematical modeling

- Experimental method

- Comparative method

3. Main research results

3.1. Scientific significance of the thesis

Contributing to perfecting the theoretical basis for reclamation of basalt soil in the Central Highlands with natural pozzolan and cement and lime additives to make the inclined wall of the yard covered with soil dam waterproofing.

3.2. The practical significance of the thesis

- The thesis has found a reasonable level of economic - technical, including: basalt soil exploited in situ mixed with finely ground natural pozzolan, PC40 cement, finely ground lime and compacted at optimum moisture to make Waterproof inclined wall for earth dam in the Central Highlands.

- The solution to improve basalt soil with natural pozzolan reduces the amount of cement used, utilizes local soil materials and utilizes an abundant natural source of pozzolan but lacks the direction of local consumption, contributing to reducing construction costs. building waterproof structures and promoting local economic development.

3.3. New contributions of the thesis

- Quantitatively elucidating the formation of colloidal CSH, CASH increases the strength, cohesion and reduces the permeability coefficient of soil improved with natural pozzolan, cement and lime through thermodynamic modeling.

- It is proposed to be mixed with P10C5L4 binder (10% finely ground natural pozzolan, 5% PC40 cement, 4% finely ground lime) mixed with basalt soil (by weight) compacted at optimum moisture content. making inclined wall structure waterproofing earth dam in the Central Highlands.

4. Conclusion and directions for further research

4.1. Conclusion

- The thesis has selected a reasonable level of 10% natural pozzolan, 5% cement and 4% lime (P10C5L4).

- Evaluation of the mechanical properties of the appropriate grade P10C5L4 at different ages: Rn; Rech; E, swelling and disintegration showed a reasonable level of coordination to ensure bearing capacity and resistance to disintegration and swelling when meeting water. The experimental results in the room and the results calculated by the mathematical model are similar.

- Reasonable reinforcement mix P10C5L4 with coefficients varying from about 5´10-6 cm/s to 1´10-6 cm/s, meeting the requirements of waterproofing structures for small and medium earth dams in the Central Highlands. Applying slanted wall structure using improved soil mixture to waterproof the soil dam being permeable, the calculation results show that the saturation line is in the safe zone of seepage, proving the waterproofing effect of the improved soil mixture. create.

- With this mixed-use inclined wall structure, the advantages of locally available materials have been maximized, the construction solution is not complicated, the construction progress is fast, and the quality is guaranteed to meet the technical requirements.

4.2. Further research directions

- Studying more mixtures of improved soil with different soil types in the Central Highlands;

- Experimental application in practice as a waterproofing structure for an earth dam in the Central Highlands;

- Studying the influence of pH, ambient temperature on the development of CS-H+CASH minerals as well as the strength of the improved soil mixture by thermodynamic model in the following studies.

See Detail: SUMMARY OF THESIS - NGUYEN HUU NAM