Impact of Particle Morphology on the Shear Behavior of Quarry Dust/Sea Sand + Concrete Interface in Geotechnical Structures

This study investigates the influence of particle morphology, including size, shape, and surface characteristics, on the shear behaviour of quarry dust, sea sand, and river sand in conjunction with concrete interfaces within geotechnical structures. Sieve analysis and modified direct shear tests were conducted on soil samples to analyse the shear strength characteristics of the soil-concrete interface. Image analysis was used to determine the morphological parameters such as angularity, roughness, sphericity, and roundness, and correlations were developed to predict the shear behaviour. When comparing the coefficient of uniformity $\left(C_{u}\right)$ values of the quarry dust, river sand, and sea sand samples, it was identified that higher $\mathrm{C}_{\mathrm{u}}$ values correspond to higher friction angles and interface friction angles. The friction angle has increased by 4.7% and 15.6%, respectively, at the soil interface and the soil + concrete interface when the $\mathrm{C}_{\mathrm{u}}$ value rises. Additionally, an increase in particle sizes increases the shear strength of samples. For instance, for a normal stress of 150 kPa, when the particle size increases from 0.075 mm to 2.36 mm, the shear strength increases by 21.2%. Further, the angular-shaped quarry dust particles exhibit an enhanced friction angle and interface friction angle by 10.8% and 12.4%, respectively, with an increase in angularity from 1.091 to 1.122, compared to spherical or rounded particles. Additionally, with an increase in regularity from 0.76 to 0.81, the interface friction angle decreased from $27.4^{0}$ to $24.8^{0}$, and the friction angle decreased from $32.4^{0}$ to $28.9^{0}$, marking percentage decreases of 9.7% and 11.0%, respectively. These findings underscore the crucial role of particle morphology in influencing the shear behaviour of quarry dust + concrete, sea sand + concrete, and river sand + concrete interfaces, with implications for the design and construction of geotechnical structures.