توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱EFFECT OF SILICA FUME ON HYDRATION HEAT AND STRENGTH DEVELOPMENT OF HIGH STRENGTH CONCRETE
نویسنده(ها): ،
اطلاعات انتشار: سومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۵
Recently, silica fume became a vital ingredient for producing concrete in aggressive hot climate of Iran. In mass structures heat generation due to hydration of cement and strength properties are two important parameters which affect service life of structures. In the early age the temperature in the body of mass concrete is high and tensile strength is low. This special condition may lead to occurrence of thermal cracks. In the present study, concrete specimens with water cement ratio 0.3, were made and 0, 10 and 15 percent Portland cement replaced with silica fume. Temperature rise of the specimens was monitored just after casting in a semi adiabatic box. Temperature rise was recorded for 7 days. Furthermore, compressive strength of the cubic specimens from 1 day after casting to 91 days was measured. The results declared that hydration heat regime is affected by silica fume percent. The mixes with both 10 and 15% silica fume, had peak temperature about 6ºC lower than the specimens without silica fume. Furthermore, peak temperature of the specimens without silica fume occurred 23 hours after casting, while it became about 31 hours for silica fume specimens. The slope of cooling zone of hydration regime in the specimens with 10% silica fume is very mild compare with the others. On the other hand, 10% silica fume enhanced
compressive strength more effectively. These results demonstrated that hydration heat and strength development of mass concrete are affected by silica fume content and higher replacement of this pozzolan material may adversely affect service life of structures. s<\div>

۲Preparation and characterization of concrete containing TiO2 nanoparticles for photocatalytic degradation of pollutants
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی تصفیه فاضلاب و بازیافت آب، فناوری ها و یافته های نو، سال
تعداد صفحات: ۶
Innovation of novel technologies such as biotechnology and nanotechnology in recent years has provided interesting trends in advanced materials and processes which are introduced for air and water purification, as well as agricultural and urban waste water refinery. A useful method for researchers is to use nano photocatalysts, especially titanium dioxide nanoparticles, to reduce environmental pollution of the micro organisms via oxidation and chemical reduction process. In this study, the photocatalytic and purifying capability of concrete samples containing TiO2 nanoparticles are investigated experimentally. Two concrete mix designs with water–binder (w\b) ratio equal to 0.45, including reference mixture (free of nano–TiO2) and a mixture contained 1% Nano–TiO2 by weight of binder were prepared. Concrete Samples were cured for 7 days in standard conditions. In the next step, photocatalytic degradation of standard Rhodamine–B solution (with chemical formulation of C28H31ClN2O3produced by Fluka Inc.) exposed to UV light in touch with concrete samples was studied by monitoring the gradient of solution’s concentration versus time. This process performed by spectrophotometric analysis of both provided solutions (reference and 1% wt. containing nanoparticles) in 553nm wavelength. Obtained results illustrate that concrete sample containing nanoparticles would significantly reduce the solution’s concentration via degradation of Rhodamine–B. Thus, while the cement consumption is reduced, concrete samples containing nanoparticles exhibit the photocatalytic and purifying capability. In the other hand, some improvements in mechanical properties (tensile and compression strength) have been observed in these samples<\div>
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