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

  • Nevin Aly
    Affiliation

    Engineering Science and Mathematics Department, Faculty of Petroleum and Mining Engineering, Suez University, 43533 Suez, Egypt

  • Ayman Hamed
    Affiliation

    Geological Engineering and Geophysics Department, Faculty of Petroleum and Mining Engineering, Suez University, 43533 Suez, Egypt

  • Ahmed Abd El-Al
    Affiliation

    Civil Engineering Department, Faculty of Engineering, Najran University, P.O. Box 1988, Najran, Saudi Arabia; Geology Department, Faculty of Science, Al Azhar University, Assuit Branch, 71515 Assuit, Egypt

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.
 

 

Keywords: stone decay, clay swelling, hydric dilation, drying / wetting cycles, Helwan limestone
Published online
2020-04-21
How to Cite
Aly, N., Hamed, A., Abd El-Al, A. “The Impact of Hydric Swelling on the Mechanical Behavior of Egyptian Helwan Limestone”, Periodica Polytechnica Civil Engineering, 64(2), pp. 589-596, 2020. https://doi.org/10.3311/PPci.15360
Section
Research Article