توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Investigation of Nano–SiO2 Effects on High–Volume Fly Ash Concrete
اطلاعات انتشار: نخستین کنفرانس بین المللی تکنولوژی بتن، سال
تعداد صفحات: ۹
In this paper, laboratory studies have been done on the mechanical properties and microstructure of high–volume fly ash concrete incorporating nano–SiO2. The results were compared with those of ordinary Portland cement (OPC) and of high–volume fly ash concrete (HFC). In this study, in order to determine effects of nano–SiO2 additives on properties of y ash mortar, 1%, 2% and 4% of nano–SiO2 was added to the mixes as a replacement of cement to investigate their physical properties and micro–structures. In all mixtures, water–binding ratios of 0.5 and 0.6 have been used. Also in all mixtures except OPC samples, constant substitution amount of 40% of y ash was proposed. Assessments of these concrete mixes were based on short–term and long–term performance. Compressive strength tests on specimens cured at 3, 7, 28, 56, 90 and 120 days, tensile strength tests on specimens cured at 7 and 28 days and finally SEM test on selected specimens cured at 7 and 120 days were carried out. Results indicated that because of low pozzolanic reaction of fly ash, early strength of HFC decreased considerably. Besides, nano–SiO2 in addition to its effects as a ller, because of considerable increase of surface–to–volume, promoted pozzolanic reaction. So, it results in developing the strength of HFC especially in early ages. Also, by increase of curing age of concrete because of activation of fly ash and decrease of Ca(OH)2 due to hydration, strength was developed relative to OPC sample.<\div>

۲Synthesis of “Imogolite” Fibers
نویسنده(ها): ، ،
اطلاعات انتشار: چهاردهمین همایش بین المللی نفت، گاز و پتروشیمی، سال
تعداد صفحات: ۸
In the upgrading process of the crude oil a variety of catalysts are used to separate heavy metals and pollutants. The major shortcoming of these catalysts is their quick deactivation. The aluminosilicate nanotube (imogolite) has extensive application in the upgrading process due to the large surface area and fiber structure. imogolite is a naturally occurring hydrated aluminosilicate polymer with a net composition (HO)3AL2O3SiOH. it forms hollow tubes with an external diameter of 2nm and lengths ranging from about 100 nm to several micrometers. one of the major synthesis methods of imogolite is the sol –gel reaction. in this study alumimium –sec–butoxite ASB and tetraethoxysilane TES were mixed with a particular ratio under the nitrogen atmosphere, using a glow box. after a three days reflux at 100 C, the sample is separated through the adjustment of PH in an ammonia solution. inorder characterize the sample , infra–red IR spectroscopy, X–ray and TEM transmission electron micrograph techniques were used . the results indicated that the synthetic samples has the structure for imogolite.<\div>

۳a four–lumped kinetic model to study propene oligomerization over HZSM–5 Zeolite
نویسنده(ها): ، ،
اطلاعات انتشار: اميركبير، سال
تعداد صفحات: ۷

۴Implementation of ANFIS in ACO to optimize cost and strength of crumb rubber concrete
نویسنده(ها): ، ،
اطلاعات انتشار: دهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۱۲
The aim of this study is to find the lowest cost concrete mixture subject to a specified compressive strength and finding the highest strength mixture. Some mix designs of crumb rubber concrete containing silica fume were gathered from literature and less than half of them were trained an Adaptive Network–based Fuzzy Inference system. Ant Colony System algorithm was applied as optimizer using ANFIS as compressive strength evaluator. Other design data verifies the results of ANFIS and ACS and approves their great capability in modeling and optimizing of CRC concrete mixture, respectively.<\div>
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