Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete

Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development.

Damage Analysis of Composite Sheet Under Thermal Load

The goal of this research is to carry out a 3-dimensional finite detail approach evaluation of a composite plate cracked under thermal loading. The results of the mechanical properties of the composite, the orientation angle of the fibers, the geometric form of the plate, the thermal loading and the crack length had been studied to show their influence on the variation of the integral J. It is concluded that the integral J increases with the increase of crack size, temperature variation and reduce in fiber orientation perspective (e). To complete the work a probabilistic analysis was carried out.

Bamboo as future bio-industrial material: Physical behaviour and bending strength of Malaysia’s Beting bamboo (Gigantochloa levis)

In this paper, bending strength and physical properties (specific gravity, dimensional stability and equilibrium moisture content) of a Malaysian bamboo locally known as Beting bamboo (Gigantochloa levis) are addressed. Characterizations of physical and bending strength of G. levis in terms of the variability of location along culm height (top, middle, bottom), culm section (nodes and internodes), fiber orientation (longitudinal, tangential and radial) and culm layer (outer and inner) were conducted. Comparison of these properties is also made to some bamboo and commercial timber species. It was found that G. levis has favorable physical and mechanical properties although the specific gravity of G. levis has tendency to be on the higher side. The characteristics studied were found to have some variability at different locations, sections, and directions. There was variability in terms of bending strength along with the culm height of bamboo. It is indicated from this study that the bending strength and physical properties of G. levis were found to be satisfactory.