Pham Ngoc, T, Fatahi, B & Khabbaz, M 2018, 'Impact of Liquid Whey Waste on Strength and Stiffness of Cement Treated Clay', New Developments in Soil Characterization and Soil Stability, Civil Infrastructures Confronting Severe Weathers and Climate Changes Conference, Springer, Cham, Hangzhou, China, pp. 1-10.View/Download from: UTS OPUS
The reuse of whey waste, a by-product of the dairy industry, is an emerging issue due to the environmental impacts. Some previous experimental studies have indicated that whey waste can be used as an admixture for cement-based materials, including mortar and concrete, to reduce the setting time and increase the workability, thus reduce the amount of required cement. However, influence of whey waste on cemented soil has not received sufficient attention. This study investigates variations of unconfined compressive strength (UCS) and Young's modulus (E) of cemented Kaolin clay when water in cement slurry was replaced by different whey waste proportions. Unconfined compression tests were conducted on treated specimens after two different curing times, namely 14 days and 56 days. Stress-strain relationship in each test was used to compute UCS and E at different dosages of cement and whey waste. Results of the experiments show improvements of UCS and E only for specimens when less than 10% water in cement slurry was replaced by liquid whey waste at 56 day-curing age, regardless of cement dosage. For the other cases, the presence of whey waste resulted in reductions of both UCS and E, indicating that although whey waste can be used to improve mechanical properties of cement treated clay, the optimum dosage should be selected very carefully to minimize the adverse effects. Different responses of UCS and E with curing age, dosages of cement and liquid whey waste are explained while discussing about the effects of lactose (milk sugar) available in whey waste acting as a retarding agent.
Pham Ngoc, T, Li, D, Fatahi, B & Khabbaz, H 2017, 'A review on the influence of degree of saturation on small strain shear modulus of unsaturated soils', Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, International Conference on Soil Mechanics and Geotechnical Engineering, ISSMGE, Seoul, Korea, pp. 1225-1228.View/Download from: UTS OPUS
Small-strain shear modulus (Gmax) is an important parameter in the analysis and design of structures resting on liquefiable soils, particularly under dynamic loads such as earthquakes. In real condition, soil layers near the ground surface consistently undergo variation of degree of saturation (Sr) due to the change of weather or loading-unloading processes that lead to the variation of Gmax. To date, this area has received limited attention and still encounters difficulties in evaluating the influence of Sr on Gmax as well as capturing the effect of hysteresis on water retention behaviour. This study concentrates on the relationship between Sr and Gmax based on available experimental data in literature. The results of the analysis show that Sr plays an important role in the magnitude of Gmax for both cohesionless and cohesive unsaturated soils, while it has a greater influence on the latter. In order to predict Gmax for cohesive soils within the full range of degree of saturation, apart from the influence of Sr on the contribution of matric suction (m), the influence of Sr on the contribution of plastic fines, salt concentration and van der Waals attraction should be additionally included.