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Article
Some Properties of Concrete Containing High Fraction Volume of Metakaolin
بعض خواص الخرسانة المحتویة على نسبة عالیة من المیتاكاؤولین

Authors: Kais J. Frieh --- Waleed A.Abbas --- Marawan Mohammed Hamid
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 1 Part (A) Engineering Pages: 230-248
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In this research, a study has been made on the effect of high fractional volume of replacement Metakaolin that results from grinding and burning the local kaolin from (Doeakhla zone / west of Baghdad / Iraq) with fineness of 18000 cm2/gm., and with temperature 700°C for one hour, on some properties of concrete (compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, density,absorption and drying shrinkage). Also, non-destructive tests have been made (Schmidt rebound hummer and Ultrasonic pulse velocity). In this study, ten concrete mixes have been used in two Groups to get a compressive strength 40 N/mm2 at 28 days. In Group A, the percentage replace of Metakaolin have been changed from (0-70) % by weight of cement with percent increment equal to 10% for each mix, andchange the maximum size of aggregates to determine the effect of changing the surface area of aggregate as variable on the properties of concrete-containing Metakaolin, The tests for all mixes were made at ages ranged from 1 day to 90 days after mixing and replacement a dosage of superplasticizer by water content of the mix to make a constant workability with slump 50±5mm. The aim of this research is tofind a type of concrete that can be used in dams as one of the types of mass concrete, concluded from this research that replacing 70% Metakaolin instead of cement mixing the compressive strength aged 90 days less than the 63%, splitting strength at 28 days less than 27%, flexural strength at 28 days less than about 27%, the modulusof elasticity at 28 days less than 54%, density of less than about 8% at 28 days, the absorption rate increases about 27% and drying shrinkage 1.65 * 10-4 at 60 days when compared all these tests with the reference concrete.


Article
Investigate About the Iraqi Attapulgite Clay as a Mineral Admixture for Concrete
التحري عن أطيان الأتابلكايت العراقية كمضاف معدني للخرسانة

Authors: Kais J. Frieh --- Waleed A. Abbas --- Samer H. Malik
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 10 Part (A) Engineering Pages: 2364-2375
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Tremendous research efforts have been directed to investigate the possibility of using the Iraqi Attapulgite clay as a mineral admixture to improve some properties of concrete. To investigate about this clay as a pozzolan, many experimental work need to be done to find the suitable conditions of temperature and time of calcinations. To study the influence of calcinations temperature, different samples of Attapulgite were prepared. The samples were grinded to fineness 2109 m2/ kg , then burned to ( 550 , 600 , 650 , 700 , 750 , 775 and 800)˚C at 1/2 hour , respectively . According to the American Standard Specifications, the strength activity index was conducted on the cubic specimens with dimensions (50 * 50 * 50) mm. The results showed that the optimum calcinations temperature was 750 ˚C. The Attapulgite samples were prepared at ( 1/2 , 1 , 1 1/2 , 2 ) hours , respectively and the temperature was 750 ˚C , then strength activity index was conducted . The results showed that the optimum calcinations time was 1/2 hour.

بذلت جهود بحثية كبيرة للتحري عن إمكانية استخدام أطيان الاتابلكايت العراقية كمضاف معدني لتحسين بعض خصائص الخرسانة . وللتحري عن مدى صلاحية هذه الأطيان وملاءمتها كبوزولانا ، لابد من القيام بتجارب مختبرية لإيجاد الظروف المناسبة من درجة حرارة وزمن حرق لإنتاج اتابلكايت عالي الفعالية . لدراسة تأثير درجة حرارة الحرق تم تحضير نماذج مختلفة من الاتابلكايت وحرقها بدرجات حرارة ( 550 ، 600 ، 650 ،700 ، 750 ،775 و 800 ) ˚سيلسيوس على التوالي ولمدة 2/1 ساعة وبعدها تم إجراء فحص مؤشر الفعالية لمكعبات من مونة الاسمنت بإبعاد ( 50 * 50* 50) ملم طبقا للمواصفات الامريكية القياسية . وقد أظهرت النتائج بان درجة حرارة الحرق المثلى هي 750 ˚سيلسيوس . بعدها تم تحضير نماذج من الاتابلكايت المحروق بدرجة 750 ˚سيلسيوس وبأوقات مختلفة من أزمنة الحرق ( 2/1 ،1 ، 2/1 1 ، 2 ) ساعة على التوالي ومن ثم إجراء فحص مؤشر الفعالية لهذه الخلطات . أظهرت النتائج بان افضل زمن للحرق هو 2/1 ساعة

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