Showing 7 results for Durability
, Ar Taleb Beydokhti, A Asiabanha,
Volume 6, Issue 1 (11-2012)
Abstract
Slake durability of rocks is an important engineering parameter for evaluating deterioration of rocks in chemical and physical agents that are related to mechanical properties of rock. The main purpose of this study is to assess the influence of the number of drying and wetting cycles under variable pH conditions and controls of mineralogical composition on durability. For this purpose, five different types of tuff were selected from different parts in north Qazvin city. The samples were subjected to multiple-cycle slake durability testing with different pH values solution. Also the slake durability tests in saturated condition on samples, petrographical analyses and basic physical - mechanical test were performed. In addition, to assess the influence of mineralogical composition on durability, the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after fifteen cycles were also determined by XRD analyses. It was concluded that the slake durability of tuff is independent of the pH in acidic solution circumstances. Mineralogical composition, fabric and weathering rate are considered to have a greater influence on the slake durability of tuff. A strong relationship between the point load strength and the fifteenth-cycle slake durability index is found in the rock types studied.
Mr Nikudel, H Bahramkhani, M Khamech, A Jamshidi,
Volume 8, Issue 2 (11-2014)
Abstract
One of the most important issues in the design and implementation of engineering structures is to evaluate and investigate their durability against processes of consecutive wear, wet and dry. The durability of rock is resistance against chemical and physical weathering, the shape, size and status of the initial appearance in a long time and environmental conditions prevailing in the rock, hence it is important to evaluate the durability of rock. Since the device of standard durability (Franklin & Chandra, 1972) designed to evaluate and investigate durability of soft and argillites rocks. So, appears to be essential to design a durability device, which can evaluate hard rocks. For this purpose, Researchers of the Department of Geological Engineering, Tarbiat Modares University, durability device as "large-scale durability device " was designed and built which the length and diameter of the device, is 6 and 4.3 times standard durability device, respectively, and needs 10 samples with weight of 400 to 600 g. In order to investigation the applicability of this device for hard rocks durability, we selected 17 building rocks samples of the igneous, sedimentary, metamorphic and pyroclastic rocks. Then their mineralogical, physical and mechanical properties were investigated. More, experiments of standard and large-scale durability up to 15 cycles were performed and data obtained were analyzed. The results show that, the large-scale durability device than standard durability, have more applicability for evaluating the durability of hard rocks.
Davood Fereidooni, Mohammad Hossein Ghobadi,
Volume 9, Issue 2 (9-2015)
Abstract
In order to assess mineralogical composition influence on durability and strength of rocks, four samples of hornfelsic rocks were selected from southern and western parts of the city of Hamedan, west of Iran. These rock samples were subjected to mineralogical, physical and mechanical tests in the laboratory. Also, they were evaluated in 15 cycles of slake-durability testing in different pH of sulfuric acid solutions and XRD analysis. Based on the results, the type and amount of minerals, their density and hardness had an influence on the uniaxial compressive strength and the slake durability index of tested rocks. That means, presence of non-dissolved minerals such as graphite in studied rocks, decreases Unconfined Compressing Strength (UCS) but increases the slake durability index. The results of slake-durability test indicated that weight loss of the samples at initial cycles was found to be higher than the end cycles. Also, in these samples, initial minerals in the fresh samples were not exchanged by secondary minerals such as clay minerals. Therefore Hamedan hornfelsic rocks are approximately resistant when were put under accelerated chemical weathering and degradation in the laboratory and natural chemical weathering.
Mh Ghobadi, R Babazadeh,
Volume 10, Issue 1 (8-2016)
Abstract
Strength and durability of sandstones and their influences from natural conditions, are the most important factors which should be considered as engineering materials. In this study, the effect of freeze-thaw and salt crystallization phenomena on strength and durability of upper red formation sandstones collected from southern part of Qazvin province was investigated. Nine specimens of sandstones (specified by A, B, C, CG, S, S1, Tr, Min and Sh) were collected from different part of studied area, then their physical and mechanical characteristics were determined. In order to assessing the effect of freeze-thaw on physical and mechanical characteristics of sandstones, 60 cycles of freeze-thaw test was performed. Also in order to investigate the effect of salt crystallization on strength of studied sandstone, sodium sulphate crystallization test (100% weight solution of Na2SO4) was carried out in 20 cycles. Physical and mechanical characteristics of sandstones such as point load index, Brazilian tensile strength, wave velocity (Vp) and weight loss were computed after different cycles. To evaluate the effect of freeze-thaw and salt crystallization phenomena on durability of sandstones, slake durability test was conducted on specimens subjected to mentioned processes and changes occurred in slake durability index in 15 cycles were investigated. Based on results obtained from current study, it could be concluded that in comparison to freeze-thaw, salt crystallization can considerably reduce the strength and durability of sandstones and deteriorate them. Also it was found that index tests such as point load index, Brazilian tensile strength, wave velocity (Vp) and weight loss can predict the behavior of sandstones in different cycles of freeze-thaw and salt crystallization tests.
Mh Ghobadi, M Kapelehe ,
Volume 10, Issue 4 (5-2017)
Abstract
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.
, , ,
Volume 15, Issue 3 (12-2021)
Abstract
Mr. Mehdi Hashemi, Dr Davood Fereidooni,
Volume 17, Issue 2 (9-2023)
Abstract
In this research, the durability and deterioration of two historical stone monuments, including the Dashkasan rock temple and the historical stone inscriptions of the Sojas cemetery in the south of Zanjan province, were investigated. For this purpose, two stone block samples were selected from each historical work for laboratory study. Based on the geological investigations, the historical monuments of the Dashkasan rock temple were carved on tuffs of the Karaj Formation. According to the thin section study, the Dashkasan temple rocks composed of the crystal vitric tuff and lithic vitric tuff and the samples of the historical inscriptions of the Sojas cemetery were limestone and very fine-grained sandstone, quartz being the dominant mineral of these rocks. In terms of physical characteristics, the samples studied have medium density and porosity. In terms of durability and deterioration, all four samples were subjected to 15 cycles of the slake durability test in normal water and sodium sulphate solution. The degradation function model and half-life of all four samples were determined and analysed. The results show that all four samples have a lower slake-durability index in sodium sulphate solution than in normal water. Due to the presence of quartz in lime or clay matrix, the samples of historical stone inscriptions from Sojas cemetery have more water absorption and porosity and are more durable, and their half-life is lower than the samples from Dashkasan rock temple.
