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An investigation of shear strength of G6 material with emphasis on density and moisture relationships
Thesis (MEng)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613875829997568 |
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| access_status_str | Open Access |
| author | Waugh, Keagan |
| author2 | Jenkins, Kim |
| author_browse | Jenkins, Kim Waugh, Keagan |
| author_facet | Jenkins, Kim Waugh, Keagan |
| author_sort | Waugh, Keagan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/134871 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:43:06.129Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/134871 An investigation of shear strength of G6 material with emphasis on density and moisture relationships Waugh, Keagan Jenkins, Kim Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Granular materials -- Permeability Strength of materials Road materials -- Testing Shear strength of soils -- Testing Thesis (MEng)--Stellenbosch University, 2025. Waugh, K. 2025. An Investigation of Shear Strength of G6 Material with Emphasis on Density and Moisture Relationships. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/4f494bee-4224-46a6-85f9-917892f78df9 ENGLISH ABSTRACT: This research study investigates the shear strength of a typical South African G6 unbound granular material, with emphasis on density and moisture relationships. Unbound Granular Materials (UGMs) are widely used materials in road construction in South Africa due to their quality, abundance and availability across most of the country. The quality of material for each road construction project is thoroughly analyzed with specific design requirements for each material used, to achieve the required performance and relative certainty of the pavement structure. The experimental design of this study incorporates a G6 granular material undergoing several laboratory tests. The laboratory tests consisted of monotonic – and dynamic triaxial testing to determine the shear strength and stiffness of the material. The shear strength and stiffness consist of the materials cohesion and friction angle, and the resilient modulus (Mr) of the G6 material, respectively. A greater understanding of the material characteristics of the G6 granular material must be developed, which led to various property tests being carried out. These tests include grading analysis, and maximum dry density (MDD) and optimum moisture content analysis (OMC). The grading was performed by using the Power (Fuller) Grading method, which is defined by the principle that to achieve the material’s maximum density, the voids between large particles must be minimized with finer particles. This principle was employed, and a grading was developed. Once the grading is completed, a relationship between moisture and density was developed to identify an optimum moisture content that will yield the maximum dry density. The results of the moisture content and dry density were calculated as 5,7% and 2220kg/m3, respectively. These results were carried out for both size specimens which include a small-scale sample (152mm diameter by 300mm height) and large-scale sample (300mm diameter by 600mm height). The samples were compacted using a vibratory hammer corresponding to the sample size, carefully bagged and sealed, and left for 24 hours for initial cohesion development and prevention of moisture loss. Through monotonic triaxial testing, the shear strength parameters were investigated and determined. The monotonic triaxial testing consisted of two different sized specimens, which includes a small-scale- and a large-scale specimen. Moreover, several tests were conducted for varying densities and varying moisture levels. It was found that the cohesion and friction angle were significantly influenced by the various density and moisture levels, in which a relationship was found. This relationship indicated that at high densities and low moisture content, the cohesion was the highest, and with increasing moisture content, the cohesion of the material decreased. The friction angle was more sensitive to density variations, where it was observed that higher densities yielded higher friction angles. Through dynamic triaxial testing, the load spreading ability (Resilient Modulus) was investigated and determined. The dynamic tests were conducted at three confinement pressures (100kPa, 50kPa and 25kPa), four deviator stress ratios (10%, 20%, 30% and 40%), and varying density and moisture levels. It was observed that the resilient modulus (Mr) increased with increasing confining pressure and increased with increasing deviator stress ratios. Moreover, higher resilient modulus results were experienced at higher densities, which show that denser materials have improved stiffness and load-spreading capabilities. At higher moisture levels, the resilient modulus decreased which shows that excess water is detrimental to the performance characteristics of material and pavement structure. It is important to note that the LVDT data and actuator data were thoroughly investigated and compared, for all cases of density and moisture variations, where the LVDT data was inaccurate in some cases. In conclusion, the tests performed highlighted the importance of moisture content and density when considering the shear strength parameters of unbound granular materials. Based on the density and moisture levels calculated, the relationship identified indicates the materials characteristics, behavior and performance, where high density and optimum (and lower) moisture levels yield higher shear strength results. Although the study does not accurately represent in-situ grading, the tests were performed as accurately as possible according to SANS methods. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2026-01-13T11:59:33Z 2026-01-13T11:59:33Z 2025-12 Thesis https://scholar.sun.ac.za/handle/10019.1/134871 Stellenbosch University 146 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Granular materials -- Permeability Strength of materials Road materials -- Testing Shear strength of soils -- Testing Waugh, Keagan An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title | An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title_full | An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title_fullStr | An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title_full_unstemmed | An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title_short | An investigation of shear strength of G6 material with emphasis on density and moisture relationships |
| title_sort | investigation of shear strength of g6 material with emphasis on density and moisture relationships |
| topic | Granular materials -- Permeability Strength of materials Road materials -- Testing Shear strength of soils -- Testing |
| url | https://scholar.sun.ac.za/handle/10019.1/134871 |
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