الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
This thesis aims to examine and compare weathering (processes, mechanism, intensity and rate) in Alexandria and Saqara that have been chosen to represent tow widespread environmental types in Egypt {semi-arid, marine, urban and industrial area (Alexandria) and arid, desert area (Saqara)} suffering from tow main weathering processes, namely: Salt weathering, wetting and drying as noted from the field study and the laboratory analysis. br The rock salt content and type at both areas indicate how intensity salt weathering acting on weak sedimentary rock (sparitic limestone Alexandria and argillaceous limestone and calcareous shale at Saqara) at such environmental conditions (temperature and relative humidity). The main salt weathering mechanism in Alexandria are salt crystallization, thermal expansion and salt hydration while in Saqara is mainly salt crystallization and thermal expansion. br The rate of salt weathering is 1.52mm-year for close to seashore, and mm-year for those away from seashore in Alexandria, but it is only 0.3mm-year in Saqara. This related to rock salt content number and duration of weathering cycles that is larger numbers and shorter duration in Alexandria than Saqara. br The weathering intensity (class) in Alexandria is III and IV while at Saqara it is low intensity (class III only). This also confirm and clarify the intensity of the destructive environmental conditions on construction material (especially on the sparitic limestone in Alexandria) of these excavations. br Wetting and adrying associated with insulation heating is also effective and reduce rock strength facilitating rock salt weathering to effect no rock texture on all scales. This process is more effective in Alexandria than Saqara as the moisture source (relative humidity, seaspeary, percolated surface water) in Alexandria more than Saqara (condensed air moisture only) and so, the resultant weathering intensity and rate of weathering in Alexandria are higher than those in Saqara.