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Register a new userThe Effect of EDTA on the Setting Time of Portland Cement, and Clinker
تأثير مادة EDTA في زمن الأخذ لكل من الاسمنت البورتلاندي و الكلنكر
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هاني طالب( باحث )
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تؤثر المادة Na٢ - EDTA (ملح ثنائي الصوديوم ل: ايتلين ثنائي أمين رباعي حمض الخل) تأثيرًا كبيرًا في زمن أخذ كل من الكلنكر و الاسمنت البورتلاندي، حيث يتغير زمن كل من بداية الأخذ و نهايته تغيرًا كبيرًا عندما تضاف نسبة صغيرة من Na٢- EDTA إلى الخلطة لاتتجاوز ٪ ١ من وزن الاسمنت. يستدل من التحليل الكيميائي أن تركيز شوارد الكالسيوم الكلي في الطور المائي لعجينة الاسمنت يزداد بوجود مادة Na٢-EDAT, أما تركيز شوارد الكالسيوم الحرة في الطور المائي فإنه يقل بازدياد نسبة ، Na٢-EDTA المضافة، إذ إن هذه المادة تشكل معقدات مخلبية مع الكالسيوم وبعض المعادن الأخرى مثل الحديد و المغنزيوم في درجات PH مرتفعة، كما هو الحال في خليط الاسمنت مع الماء.
The substance, Na٢-EDTA, disodium salt of Ethylene Diamine Tetra Acetic acid, has big influence on the setting time of both Portland cement, and clinker. The time of initial, and final setting is remarkably changed in the presence of a small percentage of Na٢-EDTA (less than ١٪ of the cement weight). The chemical analysis indicates that the total concentration of calcium in the aqueous phase of cement increases in the presence of Na٢-EDTA. While, the concentration of free calcium ions in the aqueous phase decreases as the percentage of Na٢-EDTA increases. Na٢-EDTA forms chelating complexes with calcium, and some other metals such as iron and magnesium at high PH values, as in the case of a mixture of cement and water.
References used
S. Mindess, and J.F. Young, “Concrete”, Prentice- Hall , Inc1981
H. Taleb,”Anlytical and Mechanistic Aspects of the action of selected retarderds on the hydration recaction of tricalcium silicate, the major component of Portland Cement” Ph.D Dissertation, Georgetown University. U.S.A1985
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