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Effect of Calcined and Non Calcined Fly Ash Addition on The Strength of Concrete
اثراضافة الرماد المتطاير المحروق وغير المحروق على متانة الخرسانة

Authors: Huda N. Kalifa --- Omar Jalaa Yahya --- Younes Mohsen
Journal: journal of kerbala university مجلة جامعة كربلاء ISSN: 18130410 Year: 2015 Volume: 13 Issue: 1 Pages: 141-148
Publisher: Kerbala University جامعة كربلاء

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Abstract

The present work studies the effect of calcination of the fly ash that added to the concrete to enhance its strength. The fly ash added to the concrete batch in different weight ratios 20, 25, and 30 %. The fly ash added in two groups, group1: Fly ash without firing (Calcination) with particle size ranging from 0.425-1.18 mm. while group 2: Fired (calcined) fly ash at 700 ºC for 4 hours. The X-ray diffraction for calcined fly ash shows that the organic compound shown in the non calcined fly ash was disappeared and the main compounds was silica and millite. Slump test was achieved for the fresh concrete with the addition of calcined fly ash, which shows a clear reduction. The absorption of water during curing was reduced by calination the added fly ash. Also the strength of concrete was enhanced in the case of calcination the added fly ash more than in the case of adding non calcined fly ash.

البحث الحالي يدرس تأثير حرق الرماد المتطاير المضاف الى الخرسانه لتحسين مقاومتها.الرماد المتطاير المضاف الى خلطات الخرسانه يكون بنسب مختلفة 20,25,و30%. ويكون الرماد المضاف بنوعين الاول بدون حرق ويكون الحجم الحبيبي يتراوح بين 0.425-1.18ملم بينما النوع الثاني يكون الرماد المحروق بدرجة حرارية 700درجة مئوية ولمدة 4 ساعات.فحص حيود الاشعه السينية للرماد بعد الحرق اوضح بزوال المركبات العضوية التي كانت موجودة بالرماد غير المحروق المركبات الاساسية الموجودة هي سليكا والملايت. اختبار الهطول اجري للخرسانه الطرية بأضافة الرماد المحروق تحسنت بشكل ملحوظ وقلت وكذلك الامتصاصيه خلال التخمير قلت بأستخدام الرماد المحروق. المقاومة ازدادت للخرسانة المضاف له رماد محروق اكثر من اضافة رماد غير محروق .


Article
Reinforcement Steel Corrosion Reduction by Using Fly Ash from South Baghdad Power Plant

Authors: Amel S. Merzah --- Huda N. Kalifa --- Taha H. Abood --- Ishraq Abdulkarim
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2013 Volume: 14 Issue: 1 Pages: 15-24
Publisher: Baghdad University جامعة بغداد

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Abstract

Corrosion- induced damage in reinforced concrete structure such as bridges, parking garages, and buildings, and the related cost for maintaining them in a serviceable condition, is a source of major concern for the owners of these structures. Fly ash produced from south Baghdad power plant with different concentrations (20, 25 and 30) % by weight from the cement ratio were used as a corrosion inhibitor as a weight ratio from the cement content. The concrete batch ratio under study was (1:1.5:3) cement, sand and gravel respectively which is used in Iraq. All the raw materials used were locally manufactured. Concrete slabs (250x250x70) mm dimensions were casted, using Poly-wood molds. Two steel bars were embedded in the central position of each slab at the mid- height (about 35 mm), with a space of 100 mm between each other. A 16 concrete slabs were prepared (0, 20, 25 and 30) wt. % of fly ash. The specimens were partially immersed in 3.5 wt. % NaCl solution in order to predict the corrosion. Half-cell potential test technique was used to estimate the corrosion rate which is occurred in the steel bar due to the migration of chloride ions through the concrete, depending on the ASTM C876-08. The result shows that the potential values of steel in concrete were shifts to the positive direction with increasing the percentage of fly ash, because the reduction of porosity by the addition of fly ash which fill the pores and inhibit the chloride ions to reach to steel. The results also show that the further increase of fly ash (30%) the possibility of carbonation is increased which result in reduction its alkalinity, thereby permitting corrosion of embedded steel.

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