Ibrahim Asi

Granular volcanic ash material is spread over considerable areas of Yemen including urban and suburban areas. Due to the inferior properties of this material in its natural state, it cannot be used in base and subbase layers. It is common practice, when faced with such material, to replace it with superior properties filling material. Excavated volcanic ash is disposed off by transporting it to landfill sites. Such practice is becoming increasingly costly and continuously necessitates allocation of scares and valuable new landfill sites. The problem in some urban areas is becoming an environmental issue due to the massive buildup of disposed volcanic ash material. The main objectives of this study are twofold: one to investigate the merits of utilizing waste volcanic ash as a cheap alternative to aggregate for road construction and consequently this contributes toward an efficient waste management of this undesirable material and reduces its environmental impact. The effects of using granular volcanic ash...

Road construction on sabkha terrain along the coastal regions of the Arabian Gulf and the Red Sea is often faced with different types of damage due to the low bearing capacity of sabkha deposits, especially when they are wetted. Such conditions necessitate the improvement of sabkha prior to any construction. The purpose of this investigation was to upgrade the load-carrying capacity of sabkha soil using geotextiles by varying the geotextile type, base thickness, moisture condition and the magnitude of the deviatoric stress. To achieve these objectives, a special mould was fabricated to accommodate the soil-fabric-aggregate (SFA) systems. The performance of SFA systems was evaluated by measuring the permanent deformation under the applied ‘dynamic’ load. Results of this study indicate that the selection of an appropriate geotextile type can bring about significant improvement in the load-carrying capacity of the water-sensitive sabkha soils, particularly under soaked conditions. The inclusion of a geotextile layer on top of the sabkha subgrade reduced the thickness of the graded base layer by 34%. In addition, the geotextile increased the stiffness of the sabkha subgrade and reduced the permanent deformation after a certain number of load reputations.

It is estimated that about 40 billion tons of oil shale is available in the southern part of Jordan. Several studies are being carried out to utilize this source of energy efficiently. Upon direct combustion of this oil shale, more than 50% of its quantity will be left as fly ash. Resulting fly ash is considered undesirable and environmentally hazardous. This investigation was conducted to make use of the fly ash in the modification of local asphalt mixes. The modification efficiency was evaluated by the improvement in the performance of prepared asphalt concrete mixes. To carry out this study, enough quantity of oil shale was collected from Al-Lajjoun quarries (about 100 km south of Amman, Jordan). This material was then crushed, sieved, and burned to obtain the fly ash. Chemical and physical analyses of the fly ash were then performed. Asphalt concrete mixes having different percentages of fly ash (0, 10, 50, and 100%) as a replacement of the mineral filler, material passing the 0.075 mm sieve, were pre...