The Impact of Hydric Swelling on the Mechanical Behavior of Egyptian Helwan Limestone

Abstract

This study was concerned at a limestone quarry located southeast of Helwan city, Egypt, in order to investigate the effect of hydric swelling on the geomechanical aspects of limestone rocks. The Volume of Egyptian limestones change due to the presence of clay minerals (swelling/shrinking). These changes in volume induced by changing environmental conditions, high temperature and fluctuation of the relative humidity, causes accelerated physical deterioration of limestone. The rainfall is infrequent, and it is usual for the area to have no precipitation for successive months. There is a remarkable variability in daily temperature between summer and winter. The hot and arid environment that controls the geological development can affect the engineering behavior of local sedimentary stones. Petrographic investigation by scanning electron microscopy (SEM) of Helwan limestone (biomicritic limestone) revealed the existence of smectite and glauconite within the stone. The clay fraction extracted from Helwan limestone is equal to 10 % by weight. The analysis of oriented clay mounts by X-ray diffraction (XRD) confirmed the dominance of smectite in the clay fraction.To study the effect of the clay content on the mechanical behavior of Helwan limestone, hydric swelling tests were performed at first by using a displacement sensor, afterwards, the effect of a sequence of wetting/ drying cycles on the stone strength was determined by the unconfined compressive strength (UCS) test. Results confirmed that the strength loss of the limestone is directly proportional to the degree of swelling of the clay, as expected. This highlights the importance of this parameter for selecting stones in new construction or for replacing purposes, and for establishing preventive measurements to minimize this damage in historic buildings. 

The environmental impact of air pollution on the built heritage of historic Cairo (Egypt)

“…The limestones used for the construction of the historical stone monuments in Cairo come from local middle and late Eocene outcrops (47.8-33.9 million years ago) located in Mokattam, Helwan and Giza areas (El-Nahhas et al, 1990;Ahmed et al, 2006;Park and Shin, 2009;Aly et al, 2015Aly et al, , 2020. These materials are still being used for stone replacement or rebuilding works in monuments preservation practice as well as for modern buildings.…”

Effects of Water on Natural Stone in the Built Environment—A Review

“…Studies on schists have observed a slight mass loss (Mottershead [55]) and fracturing and splitting (Wells et al [56]). Swelling and strength decrease have been related to the presence of clay minerals for limestones (Aly et al [57]) and for tuffs (Pötzl et al [58]), a process also reported for other igneous rocks such as kersantite, affecting cracking patterns (Tiennot et al [59]). Also in tuffs, the effects of wetting-drying were ascribed to the interaction between water and pore characteristics and zeolites (Lubelli et al [60]).…”

A methodological approach to define the state of conservation of the stone materials used in the Cairo historical heritage (Egypt)

“…Eocene limestones extracted from the local quarries of Mokattam and Helwan areas have been exploited for the construction of monuments in Cairo since past until today (Fitzner et al 2002;Aly et al 2015Aly et al , 2018Aly et al , 2020. Additionally, several of them were reconstructed many times partially or completely over the centuries.…”