Journal of Engineering Geology, Vol. 10, No. 4, Winter 2017

The Influence of pH of Water and Chemical
Composition on the Durability of Different Rocks from the Qom Formation, East and Northeast of
Hamedan, Iran

Ghobadi M.H., Kapelehe M.;
Deparment of Geology, Bu-Ali Sina University, Hamedan
Received: 26 Aug 2013 Revised: 30 Dec 2014
Abstract
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Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Durability is a significant parameter in engineering geology and it shows the extent of the degradability of rocks as the result of mechanical and chemical breakdowns. This phenomenon is closely linked to the composition, porosity and texture of rocks. To understand the relationship between the chemical composition of rocks and their durability the mineralogical properties of the rocks along with durability tests under both acidic and alkaline pH environments were determined. Five samples of limestone and three samples of marl were analyzed. The results revealed that rocks containing high levels of CaCo3 were affected in the acidic conditions while rocks containing high levels of SiO2 were not affected by variance in the pH of the environment. These second groups of rocks were more dependent on the texture of their constituent minerals.
Keywords: Slake durability index, pH, Mineralogical properties, Chemical composition, Texture, Qom formation.
Introduction
126873790194

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Environmental Geology is an emerging field which aims to understand the relationship between the behavior of different rock masses under varying environmental conditions (Ghobadi, 2000, 2011, 2014, Manassero & Deangeli, 2002). Durability is an important engineering parameter and this is especially true for weak rocks (Franklin & Chandra, 1972, Dick & Shakoor, 1995, Gokceoglu et al., 2000). This important parameter is defined as the degradability of rocks as a result of chemical and mechanical breakdowns such as exfoliation, hydration, solution, oxidation, and abrasion. The mineral composition of rocks and their texture are closely associated with the concept of durability (Beavis, 1985, Ghobadi, 2002 & 2006). Also, another important factor in the process of the mechanical breakdown of rocks is the pH of the fluid in which they are exposed to.
A large number of studies have been carried out to show how different environmental conditions affect the mechanical properties of different rocks such as quartzite, granite, sandstone, rock salt, dolomite, and limestone (Colbach and Wild, 1965, Ghobadi 2005, Jamshid et al, 2013). In addition, it is now clear that the mineral composition of rocks along with their texture such as crystal interlocking, surface roughness, effective porosity, crystal perimeter length, crystal area, as well as crystal shape and crystal side have a significant effect on the durability of rocks (Papadopoulos, et al., 1994, Dhakal et al. 2002, Yilmaz & Karacan, 2005, Kolay & Kayabali, 2006, Gupta & Ahmed, 2007). Singh et al., (2006) demonstrated that at pH 7 marble shows its highest strength characteristics. He also demonstrated that this strength is higher in alkaline conditions compared to acidic environments. In his 2005 paper, Singh et al. examined the durability index of shale in exposure to acidic water under laboratory conditions and he predicted the durability of shaly rocks using an artificial neural network system and a neuro-fuzzy system. Also, Sunil et al., (2006) examined the engineering properties and chemical characteristics of soil under the effect of different pH solutions.
126873790194

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

In this article, the durability of different rocks collected from the Qom formation located in east and northeast of Hamedan in water possessing different pH levels has been investigated.

Material and Methods
126873790194

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

Downloaded from jeg.khu.ac.ir at 11:31 IRST on Saturday October 28th 2017 [ DOI: 10.18869/acadpub.jeg.10.4.3699 ]

The samples were collected from east and northeast of Hamedan located in West of Iran (Figure. 1). The rocks belong to the sedimentary sequence of the Qom Formation and they form a part of the syncline. Five samples of limestone and three samples of marl were analyzed. The sampling locations are shown in Figure. 2. The samples were selected on the basis of their homogeneity in visible macroscopic characteristics such as texture and color. Each block size was about

Prior to performing the durability test mineralogical, textual, and physical properties of samples such as the specific gravity (Gs), the water absorption (ωα), the porosity (n), the saturated unit weight (γsat), and the dry unit weight (γd) were determined (Table 1).

Figure
. 1. Location map of the study area.

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Figure

. 1. Location map of the study area.

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قیمت: تومان

دسته بندی : زمین شناسی

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