| Summary: | A dissertation submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Johannesburg, in fulfilment of the requirements
for the degree of Master of Science in Engineering, 2018 === The one-dimensional (1-D) compression behaviour of sands at stress levels
that are high enough to induce significant particle breakage can be represented by
a limiting compression curve (LCC) in the compression plane, i.e. void ratio (e)
versus vertical effective stress (σ'v). Results from previous studies have shown that
the LCC reflects the combined effects of particle size distribution (PSD), particle
shape, and mineralogy. Additionally, previous studies have reported that the mean
particle size (D50) also has an effect on the LCC. The current study focused on the
effect that the broadness of the PSD and particle shape have on the LCC. To
achieve this, variations in mineralogy were reduced by considering only quartzitic
sands, and the PSDs had varying broadness but a constant D50. Eleven soil types
were tested, with particle shapes that varied from commercially manufactured
spherical beads to angular filter sand. The results confirm the findings from
previous studies regarding the way in which PSD and particle shape affect the
LCC. Correlations are presented which allow for initial assessments of the LCC of
quartzitic sands based on particle shape, PSD, and limit void ratios. The results
also show that, when the LCC is modelled in a doubly logarithmic compression
plane, there is a well-defined direct and linear correlation between its slope (ρc)
and the reference vertical effective stress at a unit void ratio (σˈr). Further testing
is recommended to determine whether this correlation is affected by variations in
D50. === XL2019
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