Articles
Construction and Building Materials (09500618)452
Porosity is among the basic physical parameters widely used in evaluating the strength characteristics of building stones. Based on the geometric shape of the stone specimen, there are two procedures for determining the porosity: 1) measurements on specimens with regular shapes and 2) measurements on specimens with irregular shapes. The present study correlates the strength characteristics of stones and porosities measured from specimens with regular and irregular shapes. To this end, samples of carbonate stones were collected from different locations in Iran. The porosity of the samples was measured for specimens with regular (nr) and irregular (nir) shapes. Next, the strength characteristics of the samples, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and point load index (PLI), were determined. Results revealed that for all samples, nr has lower values than nir. Based on the scanning electron microscope (SEM) micrographs, this difference is due to the filling of some pore spaces of the specimens with regular shapes during their preparation by the coring machine. UCS, BTS, and PLI(50) were correlated with nr and nir using simple regression analyses. The accuracy of the correlation equations was compared based on their determination coefficient (R2) and diagonal line (1:1) measures. The findings indicated that nir provides higher accuracy than nr in evaluating the UCS, BTS, and PLI(50) of the samples. The effect of dry density (ρd) on the correlations between UCS, BTS, and PLI(50) with nir was investigated using multiple regression analyses. According to the results, ρd has a positive role in the prediction accuracy of the UCS, BTS, and PLI(50). The validity and accuracy of multiple regression equations were verified according to the statistics criteria and the published data by various researchers. Using these equations obviates the need to perform the UCS, BTS, and PLI(50) tests as time-consuming and laborious efforts. © 2024 Elsevier Ltd
Dadadszadeh n., ,
Hashemi, M.,
Gazifard a., ,
Asghari-kaljahi e., E. pp. 845-852
Tabriz is one of the largest cities in Iran, with a population of more than 2 million. Marlstone is the bedrock of most areas of the city. These marls, consisting of lime and clay, are found in different colors such as yellow, olive, and gray, which mostly belong to Baghmishe and Upper Red Formations. These marls have different amounts of organic materials and in high percentages cause the formation of lignite. The physical characteristics of the marl are different and the gray marl has a high density and strength. Another important characteristic of marls is the high rate of weathering which in excavations, changes over several months and turns into soil. Therefore, marl is considered both a weak rock and a hard soil. This study, by sampling and conducting experiments, presents the physical and mechanical characteristics of gray marls in different parts of Tabriz city. The carbonate content of the mentioned marls is between 30 and 60% and their dry unit weight is between 17.5 and 20.0 kN/m3. The clay minerals in these marls also include illite, montmorillonite, etc. © 2023 selection and editorial matter, Askar Zhussupbekov, Assel Sarsembayeva & Victor N. Kaliakin; individual chapters, the contributors.
Environmental Earth Sciences (18666299)81(2)
The Meymand world heritage site (Kerman Province, Iran) is a rock-hewn village carved within a pyroclastic rock mass, Meymand Tuff. This site, having an ancient local population with an age of 2000 years, is hosted by a weak rock exposed to deterioration and weathering processes. However, our understanding of the characteristics of the Meymand Tuff is limited to some previous general studies. Therefore, in the present study, the stratigraphy and intrinsic characteristics of the Meymand tuff are investigated to determine its weathering behavior and durability. For this purpose, comprehensive field and laboratory investigations were carried out. The stratigraphy of the valley and the pyroclastic flows that had deposited the Meymand tuff were identified and outlined based on field investigations and many surveyed sections along the Meymand valley. Next, the mineralogical composition, texture, structure, physical and mechanical properties, water absorption rate, slake durability, wetting–drying durability, shrinkage potential of the fine portion, and collapse potential of the Meymand tuff were assessed through laboratory investigations. The results revealed that two pyroclastic flows had deposited the host tuff rocks of the Meymand site. These rocks have a heterogeneous texture comprising very coarse-grained clasts to the fine-grained matrix. Rock characteristics including heterogeneous texture, high porous and open structure, clay-rich mineralogical composition, high water absorption capacity, and swelling and shrinkage potential of the fine portion of the matrix have resulted in adverse behaviors in Meymand tuff. These behaviors are pertained to the strength softening, weight loss, and deterioration at wetting drying cycles. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
