Prediction of compressibility and shear strength behaviour of in-situ cohesive soil from reconstituted clay

ABSTRACT

   In the present study, simplified sample preparation and testing methodology are proposed for reconstituted clay that can predict the strength and deformation behavior of its in-situ state with minimal sample preparation disturbances. Reconstituted clay specimen was prepared in designed mould for each disturbed sample. Later, predetermined proportions of admixtures were mixed to vary the liquid limits. The test results showed that the change in compression index is directly proportional to the change in the liquid limit, moisture content, and the initial void ratio of the soil samples. However, the change in angle of internal friction was inversely proportional to the liquid limit, plasticity index, and clay fraction percentage. Scanning electron microscopy tests provided in-depth insight on the comparable pore and clay flake sizes. The proposed empirical relationships from the test results could reasonably estimate the compressibility and shear strength behavior of the in-situ clay soil from the basic index properties.

KEYWORDS:

• Reconstituted clay
• compressibility
• shear strength
• admixtures
• scanning electron microscopy

Notations

B-Bentonite clay

$\mathrm{C}\mathrm{F}$-Clay Fraction

D-Dhaka clay

$\mathrm{D}\mathrm{C}$ -Disturbed Clay

$\mathrm{D}\mathrm{B}$ -Dhaka clay mixed with bentonite

$\mathrm{D}\mathrm{S}$ - Dhaka clay mixed with sand

$\mathrm{D}\mathrm{S}\mathrm{T}$-Direct Shear Test

$\mathrm{F}\mathrm{M}$-Fineness Modulus

H-Height of the ring

$\mathrm{L}\mathrm{L}$ Liquid Limit

N-Narayanganj Clay

$\mathrm{N}\mathrm{B}$-Narayanganj clay mixed with bentonite

$\mathrm{N}\mathrm{S}$- Narayanganj clay mixed with Sand

$\mathrm{N}\mathrm{M}\mathrm{C}$-Natural Moisture Content

$\mathrm{O}\mathrm{C}\mathrm{R}$- Over Consolidation Ratio

$\mathrm{P}\mathrm{I}$-Plasticity Index

$\mathrm{P}\mathrm{L}$-Plastic Limit

R-Rajendrapur clay

$\mathrm{R}\mathrm{B}$-Rajendrapur clay mixed with bentonite

$\mathrm{R}{ }^{\mathrm{\prime }}\mathrm{C}$-Reconstituted Clay samples

$\mathrm{R}\mathrm{S}$- Rajendrapur clay mixed with sand

$\mathrm{R}{ }^{\mathrm{\prime }}\mathrm{M}\mathrm{C}$-Reconstituted Modified clay samples

$\mathrm{R}{ }^{\mathrm{\prime }}\mathrm{N}\mathrm{C}$ - Reconstituted Natural clay samples

S-Fine sand

S–1–Soil type −1

S–2–Soil type −2

S–3–Soil type −3

$\mathrm{S}\mathrm{E}\mathrm{M}$- Scanning Electron Microscopy Test

$\mathrm{U}\mathrm{D}$-Undisturbed Clay

${\mathrm{G}}_{\mathrm{S}}$-Specific Gravities of clays

$\mathrm{w}$- Moisture Content

${\mathrm{C}}_{\mathrm{c}}$- Compression Index

${\mathrm{P}}_{\mathrm{c}}^{\prime }$- Pre-consolidation pressure

${\mathrm{P}}^{\prime }$- Effective vertical stress

${\mathrm{e}}_{\mathrm{o}}$- Initial Void Ratio

$\mathrm{e}$- Void Ratio

$\mathrm{\Phi }$ –Diameter of the ring

$\varphi { }^{\mathrm{\prime }}$-Angle of internal friction

$\sigma$- Normal Stress

$\tau$- Shear Stress

${\mathrm{R}}^2$- Coefficient of determination

Acknowledgements

The authors would like to acknowledge the Military Institute of Science and Technology (MIST), Dhaka, Bangladesh, and Bangladesh University of Engineering Technology (BUET), Dhaka, for their financial and experimental support.

Data Availability Statement

All the data from the tests are available with the principal and the corresponding author to the article. It can be provided upon request to the corresponding author only.

Disclosure statement

No potential conflict of interest was reported by the author(s).