Influences of bulk structure of Calcarenitic rocks on water storage and transfer in order to assess durability and climate change impact.

Abstract

The main purpose of this study is to understand influences of bulk structure of geomaterials on water storage and transfer, in order to assess durability and climate change impact on the UNESCO world heritage sites in Alexandria, Egypt. This study deals with the responses of water towards the physiochemical and physicomechanical behaviours of Calcarenitic rocks, that are utilized in Greek and Roman monuments at Alexandria. Many vulnerable archaeological sites [2.3–2.5 m above mean sea level (M.S.L)] are identified at Alexandria, specifically at the Eastern Harbor, El-Shatby the Greek necropolis and Moustafa Kamil Roman tombs and addition to the Roman Catacombs of Kom El-Shoqafa which excavated with deepth − 18 m from the land surface. These UNESCO heritage sites suffer climate change impact (heavy rains and sea water rising) as well as multiple geoenvironmental and geophysical hazards. In this study a general outline of the various tests, surveys and analyses is presented, highlighting the most important issues related to the durability and climate change impact. This paper represents the comprehensive in-situ, field and laboratory surveys and tests undertaken in these outstanding world heritage sites. The field testing program comprises various geotechnical and geophysical field and laboratory tests aiming to define the physical, mechanical and dynamic properties of the hard soils/soft rock materials of the archaeological sites where these outstanding monuments are excavated and constracted. By analysis of linear correlations, some essential mechanisms should be underlined, which may connect the macrostructure to the microstructure of the geomaterial. A systematic method of analysis clearly appeared and emphasized the role of the bulk structure (i.e. grain size, grain contact, specific area, pore shape and microporosity) on petrophysical and petromechanical behavior of rock materials. The study revealed that the petrophysical and geomechanical properties of Calcarenitic rocks are influenced by size, shape, packing of grains, porosity, cement and matrix content, all controlled strongly by depositional fabric and postdepositional processes. The accurate analysis of the physiochemical and physicomechanical behaviours of Calcarenitic rocks that are utilized in Greek and Roman monuments at Alexandria allowed us to define the pathology of these monuments and to estimate the durability, climate change impact and ultimate geostatic loads that they can survive under their present geoenvironmental conditions.