The high brittle nature of pavement structures have been  carefully examined based on compressive, tensile strain and the harsh effects of fatigue cycle with reference to the base layer thicknesses and elastic strains during and after construction were examined. Subjection of asphalt and concrete-cement pavements to traffic loading and tyre pressure also influences the vertical stress and strain values for the asphalt and concrete materials under the same axial loading conditions. Using various fundamental equations under linear elastic conditions for the analysis of Asphalt and Concrete Cement structure revealed that both materials do respond differently to compressive and tensile stresses under similar mechanical conditions. Effect of compressive stresses and strains on concrete pavement is larger compare to asphalt pavement due to large thickness sub-base layer of its pavement structure. Both pavement layer thicknesses are independent of fatigue cycle under harsh traffic loading. Thus, concrete pavement has shown better fatigue resistance and less tensile strain values than asphalt pavements due to high pavement layer thickness regardless of the load distribution.

No abstract

In the present work, an attempt is made to use non-contact charcoal in the reduction of run-off mine goethite ore at heating temperatures above 570 °C. The reduction mechanism was adopted, following Levenspiel’s relations for the shrinking core model at different stages of reduction. The non-contact charcoal reduction approach is adopted to maximize the benefit of using CO/CO2 gases from charcoal for reduction without the need for beneficiation and concentration. The rate-controlling steps for the reduction kinetics of average particle sizes 5, 10, 15, and 20 mm at 570, 700, 800, 900, and 1000 °C were studied after heat treatment of the ore-wood charcoal at a total reduction time of 40 min using activated carbon reactor. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses were done to investigate the spectrometric phase change and metallic components of the ore sample after reduction, respectively. The average percentage of the metallic iron content (56.6, 60.8, and 61.7%) and degree of metallization (91.62, 75.96, and 93.6%) are achieved from the SEM/EDX analysis of the reduced ore sample at reduction temperatures of 570, 800, and 1000 °C, respectively. The results indicate the tendency for high carbon deposit at the wustite stage of the reduction process at the lowest of temperature 570oC and the residence time of at 10 min. This study demonstrates that diffusion through the ash layer is the controlling resistance of the overall reduction process.