Published Scholarly Output

There is general agreement that waste tyres should be better managed in order to preserve valuable resources and prevent environmental damage as a result of improper disposal. This paper describes the use of crumb rubber in concrete paving blocks. Existing block material is characterised as a composite with high compressive strength but with low toughness; the addition of rubber improves toughness while meeting minimum strength requirements. A total of 4300 rubberised concrete paving blocks were produced in a commercial plant, and 348 were tested for compression and abrasion performance, sound absorption, voids and skid resistance. The test results revealed that rubber substitution should not exceed 20% by sand volume in order to avoid excessive reductions in compressive strength. Further investigations showed that sound absorption and toughness were improved as the rubber content in the mix increased. The specimens showed a significant capability for absorbing dynamic loading and resisting crack propagation, which is beneficial for pavements that require good impact resistance properties.

Polyethylene (PE) film coated with polyurethane/nanosilica composite with varying composition were prepared and then exposed to ultraviolet radiation for accelerated weathering studies. The chemical and physical changes on nanocomposite coated PE film induced by UV exposure were studied by monitoring the changes in tensile strength, tensile modulus, elongation, carbonyl index, and visible light transmission. The effect of polyurethane/nanosilica composite coating on the durability and optical properties of polyethylene substrate was determined after 200 hrs and 500 hrs of ultraviolet exposure. There is no significant change was observed on visible light transmission for nanocomposite coated PE film after 500 hrs UV weathering. The mechanical properties of coated and uncoated PE were tremendously affected by UV exposure. PE coated with 4 µm of nanocomposite containing 6 wt% nanosilica showed less tensile properties deterioration compared to uncoated PE film after UV weathering. The surface protective coating of polyurethane/nanosilica composite with 6 wt% nanosilica content reduced the photodegradation rate of PE due to its excellent thermal stability compared to PE.

This paper presents the study of microwave signal attenuation on oil palm trees at 0.9 GHz, 1.8 GHz and 2.3 GHz frequencies. The main objective is to investigate the characteristics of propagation phenomenon by analysing the received signal strength. The experiments were made at the estate where there are straight line uniform canopies of mature oil palm trees. The measurements were carried out on the same transmission paths with different number of trees and height at trunk, leaves and fruits which obstructing the signal paths. The results have shown that excessive attenuation is due to scattering, depolarisation, fluctuation and absorption. It is strongly aggrees with the previous studies. Further studies on other types of vegetation and environments, and its seasonal differences are important as future research.