The Sahand volcano (Kuh-e-Sahand) is located in NW Iran, about 60 km E of Lake Urumieh and 40 Km SSE of Tabriz. The volcano is a stratovolcano and is dominated by pyroclastic materials and lava flows in the Miocene-Quaternary. The Mio-Pliocene volcanic rocks are exposed in the Southwest of Bostanabad (Arvanehkuh, Biukdagh, and Ghapandagh masses) East-Azerbaijan province. These rocks formed a part of the Urumieh-Dokhtar Magmatic Belt (UDMB) and consist of andesites and dacites. The rocks display a porphyritic texture and contain phenocrysts of plagioclase, sanidine, amphibole, biotite, and quartz. Based on the geochemical data and multi-elemental pattern, these rocks are medium to high-K calc-alkaline suite and show Large-Ion Lithophile Elements (LILE) and Light Rare-Earth Elements (LREE) enriched normalized multi-elemental patterns, and Nb and Ti depleted. Chondrite-normalized REE patterns of the volcanic rocks display a decrease from LREE to Heavy Rare-Earth Elements (HREE) without any Eu anomaly, indicating their formation in a subduction zone in an active continental margin. They have higher SiO2, Sr content, Sr/Y, and La/Yb ratios and lower MgO, Y, and Yb contents compared to those of normal calc-alkaline volcanic rocks and show high SiO2 adakites (HSA). Based on geochemical data, the origin of these rocks is garnet-amphibolite with the residual phase of garnet and amphibole with a titanium phase. HREE and Y depleted patterns suggest the existence of garnet and amphibole as a residue in the source. The source of these rocks was probably garnet-amphibolite possibly generated during subduction of the Neo-Tethyan oceanic slab beneath the Central Iran zone and in fact, can be termed as classic adakite. Therefore, considering the importance of adakites in inferring continental geodynamic processes, it is recommended to pay attention to their discovery and identification with the help of various petrological and geochemical methods. پرونده مقاله

Pozzolan is an additive to cement clinker that if added to the high quality cement and concrete, it can be effective in enhancing the quality of cement and concrete resulting from high quality controlled precision and repeated sampling and continuous testing. Concrete creates the cement-free concrete without any additives. Documentary reports and rigorous scientific studies have shown that good pozzolan can, in addition to increasing the chemical resistance of concrete, eliminate the defects caused by the use of conventional cement in concrete and due to the diversity of water and soil use in different areas. In this study, the effect of natural pozzolan in different grades of cement on the mechanical properties and permeability of concrete at 7 and 28 days of age is investigated. It was found that with increasing cement grade, the water absorption rate of concrete increased. Also, the effect of pozzolan on the permeability of concrete samples is increased by increasing the pozzolan water absorption rate. Also, the effect of cement grade on the compressive strength of concrete was found to decrease with increasing concrete grade. Today using alternative sources in concrete productions is important, due to its economical and environmental considerations. Pozzolans are one of these resources which decrease the environmental pollutions and production costs of concrete structures. پرونده مقاله

Based on the increasing the usage of the resources and population growth, the soil with suitable properties for civil engineering project such as pavement construction is not available. Therefore, it is obligatory that the enhancement of local soils properties should be appropriately deliberated. If for some reason it is not possible to relocate the project and replace the soil, or if the cost of soil replacement is not cost-effective, the soil remediation method should be considered so that if this method is economically and technically justifiable, it should be done. From this perspective, the effects of Nano-silica on soil compressive strength are important and necessary. In this study, a specific and different number of samples are prepared for comparison. The purpose of this study is to measure the uniaxial compressive strength of granular soils. It was concluded that Nano-silica filled pore space between Sand particles and a dense matrix were formed. This textural event caused an improvement in compressive strength of stabilized soils In this regard, the use of Nano-silica as a suitable and efficient additive in the thickening processes is recommended. پرونده مقاله

Dams are one of the most important structures for storing water in today's society due to their use in industry. The structural failure of the dam containing water, in addition to economic losses, also causes irreparable damage. This increased the importance of dam design and retrofitting. The stability of earthen dams mainly depends on the shear strength of the soil and this shear strength in earthen dams is provided by the action of friction between grains. The greater the angle of internal friction between the soil grains, the more shear stress is tolerated by the soil, and the stability of the dam increases. Synthetic materials called geotextiles that have properties such as granular materials (soil) in terms of mechanical and chemical resistance are high. The use of polymer elements in dams mainly causes more stability and stabilization of embankments. In this study, the impact of geotextiles on the Alavian earth dam in Maragheh has been investigated. For this purpose, by modeling the earthen dam with the help of various softwares, the effect of the type of characteristics of geotextile materials the height of the dam, and the location and distance between each other have been analyzed and studied. In particular, the installation of geotextiles is very efficient in static analysis and has caused the effective stress created in the dam to be zero, which is very rare. In dynamic analysis, the installation of geotextiles has reduced by 34% the most effective stress created in the dam. پرونده مقاله

One of the geosynthetics that is used in different parts of the world under surface foundations is geotextile, and relatively valid texts are available on how to use it and increase its load. But other geosynthetics have been geogrids, which have increased the load-bearing capacity of surface foundations in soft clay and silty loam soils. In this paper, our u/b variations are between 1 and 17.5 with step 205 and in three different b/B modes are 5, 10 and 15. Also, the b/B changes from 0.1 to 2 with a step of 0.25 and in three different u/B modes are equal to 0.25, 0.75 and 1. The purpose of this study is to compare the soil load in different cases of geogrid with non-geogrid. This comparison is also performed by the BCR dimensionless number, which is the result of dividing the armed soil load into the soil load without geogrid. The results of this paper showed that the presence of geogrid increases soil fertility, but from a certain extent onwards, this amount of fertility does not show much difference. In this ratio, the geogrid dimensions are equal to 17.5 times the dimensions of the foundation. The presence of geogrids increased the soil fertility, but from a distance onwards, this amount of fertility does not show much difference. This ratio is equal to 1.75 times the dimensions of the foundation. پرونده مقاله

This paper presents the development of self-compacting lightweight concrete (SCLC) incorporating pumice. Seven concrete series with water–binder ratios of 0.4 and a constant total binder content of 550 kg/m3 were designed. The pumice was added at proportions corresponding to 5%, 10%, 15%, 20%, 25% and 30% by weight of cement. The performance of mixtures was evaluated by conducting comprehensive series of tests on fresh and hardened properties. Fresh properties of mixtures were assessed by slump flow diameter, T50, V-funnel flow time and L-Box. Also hardened properties were investigated via compressive strength, flexural strength, density and water absorption. The fresh concrete test results revealed that by substituting optimum levels of pumice in SCLC, satisfactory workability and rheological properties can be achieved. 10% pumice significantly enhanced the compressive and flexural strength of SCLC at later ages. The density of the SCLC containing pumice was lower than those of the control SCLC. A lower absorption and permeability can be achieved for mixes especially mixtures incorporating 10% pumice. In general, it seems that 10% pumice can be considered as a suitable replacement regarding to the economic efficiency, fresh and hardened properties. Petrographic examination of concrete samples shows that pumice aggregates are in the range of basalt to basalt andesite and have about 30% porosity. The minerals inside the pumice aggregates include feldspar and hornblende and some quartz, as well as some fine iron oxide minerals. پرونده مقاله