The influence of Arabian Gulf environment on mechanisms of reinforcement corrosion

The reduction in the useful-service life of reinforced concrete construction in the Arabian Gulf is attributed to reinforcement corrosion. While this phenomenon is primarily related to chloride ions, the concomitant pressure of sulfate salts may accelerate the deterioration process. Another factor which might influence reinforcement corrosion is the elevated ambient temperature. While few studies have been conducted to evaluate the individual effect of sulfate contamination and temperature on chloride binding and reinforcement corrosion, the synergistic effect of these factors on concrete durability, viz.-a-viz., reinforcement corrosion, needs to be evaluated. Further, the environmental conditions of the Arabian Gulf are also conducive for accelerated carbonation. However, no data are available on the concomitant effect of chloride-sulfate contamination and elevated temperature on the carbonation behaviour of plain and blended cements.This study was conducted to evaluate the conjoint effect of chloride-sulfate contamination and temperature on the pore solution chemistry and reinforcement corrosion. The effect of chloride-sulfate contamination and elevated temperature on carbonation in plain and blended cements was also investigated. Pore solution extraction and analysis, X-ray diffraction, differential thermal analysis, scanning electron microscopy, DC linear polarization resistance and AC impedance spectroscopy techniques were utilized to study the effect of experimental parameters on chloride binding, reinforcement corrosion and carbonation.The results indicated that the concomitant presence of chloride and sulfate salts and temperature significantly influences the durability performance of concrete by: (i) decreasing the chloride binding, (ii) increasing reinforcement corrosion, and (iii) accelerating the carbonation process. To avoid such deterioration, it is advisable to minimize both chloride and sulfate contamination contributed by the mixture ingredients. Due to the known harmful role of sulfate ions in decreasing the chloride binding and increasing reinforcement corrosion, limits on allowable sulfate contamination in concrete should also be established.

Efficiency analysis of Islamic banks:a case of Gulf Cooperation Council (GCC)

Although considerable effort has been invested in the measurement of banking efficiency using Data Envelopment Analysis, hardly any empirical research has focused on comparison of banks in Gulf States Countries This paper employs data on Gulf States banking sector for the period 2000-2002 to develop efficiency scores and rankings for both Islamic and conventional banks. We then investigate the productivity change using Malmquist Index and decompose the productivity into technical change and efficiency change. Further, hypothesis testing and statistical precision in the context of nonparametric efficiency and productivity measurement have been used. Specially, cross-country analysis of efficiency and comparisons of efficiencies between Islamic banks and conventional banks have been investigated using Mann-Whitney test.