This research investigates the processing of sandwich composite structures with overall low density made up of glass fibre-reinforced polymer skins bonded to a jute fiber mat core. Jute fibers are totally biodegradable and recyclable materials, i.e. environmentally-friendly materials. Jute fibers have good insulating properties for both of thermal and acoustic energies with moderate moisture regain and no skin irritations. The current annual worldwide production of jute fibre is about 3.2 million tones used for various applications. Bag cloth industry is the biggest consumer of jute fibers available in the markets. Jute bags have gained an advantage as being an eco-friendly option instead of both of non-biodegradable poly bags that are made from petroleum and paper bags that require large quantities of wood. A huge amount of these jute fibers is wasted and goes to landfill every year, either scraped from manufacturing of jute cloth in form of slivers or end-of-life of jute bags. Therefore, an attempt was carried out in this research to use the above-mentioned valuable properties of jute fibers, to reuse the wasted jute slivers, to recycle the end-of-life jute bags for fabricating highly valuable sandwich structured composites. The sandwich composite structures are usually fabricated by attaching two thin but stiff skins to a lightweight but thick core. The jute fibre slivers were blended with chopped jute fibers that obtained from hashing the used coffee grain bags to produce a lightweight thick jute fiber mat. This jute fiber mat was padded as core material between two stiff thin skin layers. Each skin layer is constructed from a single plain woven glass fiber fabric impregnated with unsaturated polyester resin by hand lay-up technique. Finally, a lightweight sandwich composite structure with reduction of cost and CO2 emission was successfully fabricated. Appropriate applications can be introduced for these sandwich composite structures as barrier walls against the thermal and acoustic energies for interior construction, lightweight panels for furniture construction, housings for electronic equipments, etc.

Jute fiber mat reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum. Tension and three-point bending tests were carried out to evaluate the effect of fiber contents on these mechanical properties of above-mentioned composites. The results show that as the fiber weight content increases, Tensile and flexural properties (strength and modulus) increase. Fiber pull out mechanism is the predominant failure mode revealed at the fracture surfaces under tensile load as well as at tension side of composites under bending load.

Jute fiber mats-reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 2 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in a vacuum. This modification showed a better impregnation of resin throughout the jute mats and lower voids contents in the composites. Two types of impact tests, swing pendulum (Izod) and drop weight (impulse), were carried out to evaluate the effect of fiber contents on the impact properties of above-mentioned composites. The impact properties of these composites were compared with those of neat unsaturated polyester resin material. The fracture behavior of the composites that yielded from the impact tests was characterized by observation of the composites microstructure using scanning electron microscopy (SEM). The Izod impact strength increases as the fiber content increases and the improvement in the impact strength of the composites compared to that of the neat resin occurs at 32 wt%. Moreover, the fracture surface has demonstrated single matrix crack with complete fiber pull-out at a fiber content of 11 wt%, while single matrix crack with partially fiber pull-out mechanism was confirmed at fiber contents of 22 wt% and 32 wt%. The fiber contents has a positively large effect on the impulse total impact energy of the composites, e.g. the total energy increases with fiber contents of 11 and 22 wt% to about three times, whereas the total energy increases at 32 wt% to about four times compared to total energy of neat resin. Multiple matrix cracking and fiber pull-out mechanisms were revealed from the impulse impact test of the composites. Finally, this study showed that both izod and impulse impact properties can be improved by adding 32 wt% of jute fiber mats as reinforcements to unsaturated polyester matrix composites.

Jute fiber mat reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum. Tension and three-point bending tests were carried out to evaluate the effect of fiber contents on these mechanical properties of above-mentioned composites. The results show that as the fiber weight content increases, Tensile and flexural properties (strength and modulus) increase. Fiber pull out mechanism is the predominant failure mode revealed at the fracture surfaces under tensile load as well as at tension side of composites under bending load.

This research work intended to study the effect of the scratch with different scratch loads (20, 40, and 60 N) on the drop weight (impulse) impact energy of recycled needle punched natural jute fiber mats reinforced unsaturated polyester composites with 25 Vol.% fiber volume content. The fracture behavior of the above-mentioned composites was also investigated for each case. The results showed that the impact energy of scratched composites was decreased 40% by scratch load 20 N compared to that of virgin specimen and by increasing the scratch load to 40 N the loss in the total impact energy of the composites was decreased to 2% compared to that of the virgin specimen. On the other hand, the total impact energy of the composite was improved to around 10% by increasing the scratch load to 60 N compared to that of the virgin specimen. Moreover, the fracture behavior showed that the radial matrix cracks and more extensive delamination was observed in scratched specimen at a scratch load of 60 N compared to those of the virgin specimen and this leads to dissipate most of the impact energy and so the impact energy of the composites was improved at a scratch load of 60 N compared to that of the virgin specimen.

This study intended to investigate the durability of recycled needle punched natural jute fiber mats with 32 Vol.% fiber volume reinforced unsaturated polyester matrix composites by investigating water absorption and thickness swelling under the effect of hot water absorption at 100oC for 96, 192, 384 h immersion times compared to the virgin specimens. Moreover, the effect of drying of these immersed composites for 6 h at 100oC in a drying oven for different immersion times was investigated. The results showed that as the immersion time of the composites increases, the water absorbed by the composites increases and so the thickness swelling increases. On the other hand, when the immersed specimens are dried for 6 hours, the water absorption of the composites decrease compared to those of the immersed specimens and therefore the thickness swelling of the composites decreases after the specimens are dried compared to those of the immersed specimens.

Mine developments such as haulage drifts and cross-cuts are the primary access to the mining blocks of an orebody in multilevel mining systems for tabular ore deposits. Thus, their stability is of utmost importance during the planned period of production or the life of a mine plan. Many Canadian underground mines use longitudinal and transverse stoping with delayed backfill to extract tabular ore deposits. These methods require access to the orebody through a number of sill drives or cross-cuts which link the orezone to the haulage drift hence creating intersections on multiple levels. Mine development instability could lead to serious consequences such as injuries, production delays and higher operational cost. The objective of this research is to develop a hybrid approach in which deterministic numerical modelling is integrated with probabilistic methods to evaluate the stability of mine developments due to nearby mining activity. A case study comprising four consecutive mine levels in a deep underground metal mine in Sudbury, Ontario has been adopted for this study. The stability performance of the haulage drift is assessed using two separate evaluation criteria, namely Mohr-Coulomb yield function and Brittle Shear Failure. Random Monte-Carlo (RMC) technique is then employed in conjunction with Finite difference modelling software FLAC to determine the probability of instability or unsatisfactory performance of the haulage drift with respect to nearby mining sequence. In this study, the haulage drift performance is considered unsatisfactory when the yield zones or brittle shear failure around the haulage drift extend beyond the anchorage limit of the rock support. A comparison of the results from Mohr-Coulomb and Brittle Shear conditions has revealed that Mohr-Coulomb is more conservative from a design point of view. A three-dimensional, elastoplastic, finite difference model (FLAC 3D) is then constructed to simulate the case study mining orezone. The unsatisfactory performance of the intersection is evaluated with respect to mining sequence in terms of the strength-to-stress ratio computed by FLAC3D. Unsatisfactory stability performance is defined by a strength-to-stress ratio that is less than 1.4 and its corresponding extent into the rockmass around the intersection. Due to the large size of the FLAC3D model, the probabilistic simulations are conducted with the Point-Estimate Method (PEM), which requires significantly lesser number of simulations than Random Monte-Carlo (RMC). The results are presented and categorized with respect to probability, instability, and mining stage. In order to validate the numerical model, Multi-point borehole extensometers (MPBX) are installed at selected intersections to monitor the rock deformations as mining activities progress. The monitoring results revealed a lateral shift of the drift walls toward the orebody and much less deformations in the drift back. Finally, a methodology is developed to estimate the geotechnical risk of drift instability by considering the probability of failure and cost of consequence of such failure at an intersection. A 5-level risk index is derived which ranges from low to extreme. The methodology is demonstrated through an intersection from the case study mine, and the risk index is shown to vary with mining sequence. It is shown that the risk-index methodology can be used to confirm the need for enhanced supports, but it can also be used as basis for the comparison alternative mine designs.