Underground mining produces a huge amount of voids and an even larger quantity of mine waste. Overlooking these voids could lead to the possibility of ground subsidence, as well as safety issues during mining operation; while ignoring the waste, could cause environmental pollution and significant suffering. One solution to remedy both (the voids and the waste) is cemented paste backfill (CPB), which is gaining increased recognition in both the mining industry and academic research. Transforming tailings into cemented paste, and transporting this back to underground stopes, not only negates these safety issues to a large degree, but also makes it possible to put waste to good use.However, most studies involving CPB have been conducted at temperatures above 0°C; knowledge of CPB in sub-zero environments is still lacking. For this reason, this thesis investigates the mechanical behaviour of CPB in a the latter type of environment.Uniaxial compressive strength tests were carried out on a series of frozen CPB (FCPB) samples to evaluate the mechanical behaviour (e.g. compressive strengths, geotechnical features, and the stress-strain relationships) of FCPB. It has been discovered in this thesis that FCPB exhibits remarkable strength compared to CPB and, has a great resemblance to frozen soil. Factors which may affect the behaviour of FCPB were thoroughly examined. Binder contents and types were found to be irrelevant; water content, in contrast, plays a dominant role, with an optimum value of around 26% by weight. Sulphate was confirmed to have an adverse effect on the strength of FCPB due to the increasing unfrozen water content and the formation of legible ice lenses. Hydraulic conductivity tests, scanning electron microscope observations, thermal gravimetric analyses, and mercury intrusion porosimetry were also performed as subsidiary experiments to understand the geotechnical features of FCPB. This information will be of significant value for numerous practical applications.

Sub-zero saline solutions were evaluated for the improvement of chilling efficiency and product quality of broiler carcasses. In this study, four experiments were conducted to chill broiler carcasses using different saline solutions and chilling temperatures in the Meat Processing Center at California Polytechnic State University (Cal Poly, San Luis Obispo, CA) or in the processing plant at Foster Farms (Livingston, CA). In Experiment I, three salt concentrations and solution temperatures (0% NaCl/0.5°C, 4% NaCl/-2.41°C, and 8% NaCl/-5.08°C) were used to chill carcasses. The fillets in brine chilling at sub-zero temperatures showed lower shear forces than the fillets in 0% NaCl control solution. In Experiment II, three salt concentrations (0% NaCl/0.5°C, 4% NaCl/-2.41°C, and 8% NaCl/-5.08°C) were used to chill carcasses with/without pre-chilling in 0% NaCl/0.5ºC or 0% NaCl/14°C. Fillets from the carcasses in 4% NaCl/-2.41°C significantly improved tenderness (P < 0.05), with no significant difference observed for the shear force of 8% NaCl/-5.08°C, regardless of pre-chilling. In Experiment III, four salt concentrations (0% NaCl/0.5°C, 1% NaCl/-0.6°C, 2% NaCl/-1.2°C, and 3% NaCl/-1.8°C) were used to chill carcasses. The shear force of fillets decreased as the salt content increased and chilling temperature decreased from 0%NaCl/0.5°C to 3%NaCl/-1.8°C, with the lowest shear force observed in 3% NaCl brine at -1.8°C (P < 0.05). The chilling time (90 min) of 3% NaCl was reduced by 25 min (or 22%) compared to water control (115 min), with an intermediate reduction (13 - 17%) v seen for other NaCl solutions (95 – 100 min). Breast fillets showed no significant difference in chilling yield, pH, R-value, and sarcomere length for raw meats as well as in cooking yield and salt content for cooked fillets across all treatments (P > 0.05). In Experiment IV, three salt concentrations (0% NaCl/0.5°C, 3% NaCl/-1.8°C, and 4% NaCl/-2.41°C) were used to chill carcasses. The chilling time (55 min) of 4% NaCl was reduced by 35 min (or 39%) compared to the time (90 min) of water control, with an intermediate reduction (11%) seen for 3% NaCl solution. Control fillets in 0% NaCl showed a higher shear force than the fillets in sub-zero brine chilling (P < 0.05). Based on these results, broiler carcasses chilled in 4% NaCl/-2.41°C appears to be ideal to improve both chilling efficiency and meat tenderness compared to the carcasses chilled in 0% NaCl/0.5°C.