“…The author thinks that no or very little number of studies on the use of nano-VS as cement replacement can be found in literature. Volcanic scoria cones exist in large numbers around the world, such as in Syria, Turkey, Iran and others [1][2][3][4][5][6][7][8][9][10]. One may find more details on the use of VS as a substitute for Portland cement, in the chapter recently published by the author [11].…”
The objective of this study is to investigate the efficiency of volcanic scoria when added to the concrete binder at a nano-scale. Nano volcanic scoria (nano-VS) was obtained by grinding a local volcanic scoria for 6 h. Twenty-four concrete mixes with four w/b ratios (0.4, 0.5, 0.6 and 0.7) and six-replacement levels of nano-VS (0%, 1%, 2%, 3%, 4%, and 5%) have been produced. The investigated concrete properties were the compressive strength, the water penetration depth, the concrete porosity and the chloride ion permeability. Workability of fresh concrete mixes has been also determined. The efficiency factor (k) of nano-VS in terms of compressive strength was calculated using the Bolomey equation. Durability indicators have been used to globally evaluate the behavior of nano-VS-based binder concrete versus control concrete. The results revealed that the efficiency factor (k) decreased to some extent when the nano-VS content was bigger than 4%. The calculated durability indicators showed that the nano-VS contents of 3% and 4% had approximately the highest indicators values. These indicators would be helpful for concrete mix designers. Some correlations between the investigated properties were derived from the analyzed data. The modification of the microstructure of nano-VS-based cement paste has been observed, as well.
“…The author thinks that no or very little number of studies on the use of nano-VS as cement replacement can be found in literature. Volcanic scoria cones exist in large numbers around the world, such as in Syria, Turkey, Iran and others [1][2][3][4][5][6][7][8][9][10]. One may find more details on the use of VS as a substitute for Portland cement, in the chapter recently published by the author [11].…”
The objective of this study is to investigate the efficiency of volcanic scoria when added to the concrete binder at a nano-scale. Nano volcanic scoria (nano-VS) was obtained by grinding a local volcanic scoria for 6 h. Twenty-four concrete mixes with four w/b ratios (0.4, 0.5, 0.6 and 0.7) and six-replacement levels of nano-VS (0%, 1%, 2%, 3%, 4%, and 5%) have been produced. The investigated concrete properties were the compressive strength, the water penetration depth, the concrete porosity and the chloride ion permeability. Workability of fresh concrete mixes has been also determined. The efficiency factor (k) of nano-VS in terms of compressive strength was calculated using the Bolomey equation. Durability indicators have been used to globally evaluate the behavior of nano-VS-based binder concrete versus control concrete. The results revealed that the efficiency factor (k) decreased to some extent when the nano-VS content was bigger than 4%. The calculated durability indicators showed that the nano-VS contents of 3% and 4% had approximately the highest indicators values. These indicators would be helpful for concrete mix designers. Some correlations between the investigated properties were derived from the analyzed data. The modification of the microstructure of nano-VS-based cement paste has been observed, as well.
“…In the late stage, the oceanic crust was dismembered, and hot magma was injected from the slab window (Figure 13). Some parts of the magma erupted directly and made basaltic rocks that had a high similarity to the OIB composition in the HTV belt from Ararat to northern Sanandaj (Kheirkhah et al, 2009;Asiabanha and Foden, 2012;Azizi et al, 2014a;Torkian et al, 2016;Asiabanha et al, 2018). Other parts crystallized inside the lower crust and increased the geothermal gradient in the continental crust.…”
Section: Discussionmentioning
confidence: 99%
“…Some parts of intermediate-to-acidic rocks have higher ratios of Sr/Y and La/ Yb and, based on the adakite key diagrams (Defant and Drummond, 1990), are classified as adakite (Figure 10A). The high affinity of the upper Miocene--Quaternary volcanic rocks for adakite groups, as well as the accompanying high-Nb basaltic rocks, means that there is a correspondence to a postcollisional tectonic regime in northwestern Iran since the Miocene (Azizi et al, 2014a;Asiabanha et al, 2018;Torkian et al, 2019).…”
In northwestern Iran, magmatic activity occurred during three main intervals: The Cretaceous, Eocene, and Miocene-Quaternary. The first two phases of magmatic activity are more consistent with arc-type magmatism on an active continental margin; whereas the last phase, which has calc-alkaline and alkaline affinities, shows more similarity to postcollisional magmatism. Magmatic belts are mostly situated in the northern and eastern parts of the Oshnavieh–Salmas–Khoy ophiolite belt (OSK-Ophiolite) in northwestern Iran. The OSK-Ophiolite is known as the Neotethys, an ocean remnant in northwestern Iran, and extends to eastern Turkey and surrounds the Van area. This configuration shows that the Van microplate and surrounding ocean have played an important role in the evolution of magmatic activity in northwestern Iran, eastern Turkey, and the Caucasus since the Cretaceous. The Van microplate is situated among the Arabian plate to the south, northwestern Iran to the east, and Armenia to the north. The subduction of the northern branch of the Neotethys oceanic lithosphere beneath southern Eurasia has been critical in flare-up magmatism in the southern Caucasus since the Late Cretaceous. Considering the Van area as a new microplate makes understanding the geodynamic evolution of this area easier than in the many tectonic models that have been suggested before. When regarding the Van microplate, the main suture zone, which is known as the Bitlis–Zagros zone, should be changed to the Zagros–Khoy–Sevan–Akera suture zone, which extends to the eastern and northern Van microplate and western Iran.
“…A comparison of current experimental data with the results of linear regression by Awal and Shehu for control concrete [62] and power regression by Saha et al [58] is presented in Figure 11. Although, Awal and Shehu proposed different linear regressions (for control and palm oil fuel ash concretes) according to the exposure of 100 mm cube specimens up to 800 • C, their proposed regression for control concrete only reasonably predicts the residual strength of concrete for high exposure temperatures between 600 and 800 • C, while it underestimates the residual strength for exposure between 200 and 600 • C. The possible reason for this underestimated RCS can be due to the different geometry of their tested specimens (cubes), different heating regimes (exposure to peak temperature for 1 h only), and concrete of relatively lower strength (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) as compared to the current study (68-73 MPa). The power regression proposed by Saha et al was based on exposure of cylindrical specimens (100 mm × 200 mm) of ferronickel and FA concrete up to 800 • C. However, unlike Awal and Shehu, their prediction equation overestimated residual strength of concrete.…”
Section: Relationship Between Residual Compressive Strength and Upvmentioning
confidence: 99%
“…Like many other industry byproducts (FA, GGBFS, SF), VA is available in abundance around the globe, particularly in areas having active volcanos [34][35][36][37][38]. Its widespread use as a building material, especially in cement and concrete, has shown promising results.…”
This study investigated the effect of elevated temperatures on the mechanical properties of high-strength sustainable concrete incorporating volcanic ash (VA). For comparison, control and reference concrete specimens with fly ash (FA) were also cast along with additional specimens of VA and FA containing electric arc furnace slag (EAFS). Before thermal exposure, initial tests were performed to evaluate the mechanical properties (compressive strength, tensile strength, and elastic modulus) of cylindrical concrete specimens with aging. Additionally, 91 day moist-cured concrete specimens, after measuring their initial weight and ultrasonic pulse velocity (UPV), were exposed up to 800 °C and cooled to air temperature. Subsequently, the weight loss, residual UPV, and mechanical properties of concrete were measured with respect to exposure temperature. For all concrete specimens, test results demonstrated a higher loss of weight, UPV, and other mechanical properties under exposure to higher elevated temperature. Moreover, all the results of concrete specimens incorporating VA were observed before and after exposure to elevated temperature as either comparable to or slightly better than those of control and reference concrete with FA. According to the experimental results, a correlation was developed between residual UPV and residual compressive strength (RCS), which can be used to assess the RCS of fire-damaged concrete (up to 800 °C) incorporating VA and EAFS.
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