دراسة التوصيف الفيزيائي والهيدروليكي والمعدني لمادة القَضَاض التقليدية في صهاريج عدن

Abstract

Qadadh is a traditional building material in Yemeni architecture. It has been used for centuries to dams, cisterns, channels, and other water structures due to its high resistance to leakage and moistness for a long-term durability. This research aims to characterize and analyze the properties of Qadadh based on specimens taken from historic Aden cisterns for the purpose of a reproduction practice of the material. Comprehensive physical (bulk density, open porosity, water absorption, capillary absorption), hydraulic (permeability, hydraulic indicators) and mineralogical tests (XRD X-ray diffraction, XRF X-ray fluorescence, and SEM-EDS scanning electron microscopy with energy-dispersive X-ray spectroscopy) were conducted based on international specification. The findings indicated for the bulk density of Qadadh in Aden cisterns to be 1690 kg/m³, with open porosity and water absorption at 25.04% and 14.89%, respectively. The permeability coefficient was measured at approximately 17.6×10⁻⁹ m/s. These results may refer to its efficiency to prevent water leakage and a good compatibility between density and durability. Results of mineralogical analyses (XRD, XRF) revealed the mineral and chemical composition of the Qadadh. Moreover, mineralogical images of  SEM-EDS highlighted the dense structure of Qadadh which may be attributed to calcium-silicate-hydrate C-S-H and calcium- alumino-hydrate C-A-H gel formations which enhanced its waterproofing capabilities over extended periods in coastal environments.