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Some properties of accelerated cured no fine Lightweight concrete
بعضخصائصالخرسانة خفیفة الوزن الخالیھ من الركام الناعم المعجلة الانضاج

Author: Zena K.A.Al Anbori زینة خضیر عباس
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 13 Part (A) Engineering Pages: 213-224
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Thermal insulation is one of the main problems facing the engineers working inbuilding and housing sector spatially for the high summer temperature in the mostArab Gulf and spatially in Iraq, so the study of lightweight aggregate thermalinsulation (No fine concrete) is important. The experimental work consist of concretemixes (cement: porcelinite aggregate) ratios (1:4), (1:5) and (1:6) and for each mixescement content changes (200, 300 and 400) Kg/m3. Dependence on mixing (1:5) andcement content (300Kg/m3) change the water to cement ratio (0.4, 0.45 and 0.5) byweight. The research presents the tests of density, absorption, porosity, ultrasonicpulse velocity, accelerated compressive strength according to British standard (BS1881: Part 112: 1983), normal compressive strength at 7, 28 and 90-day. Light weightconcrete was obtained of density ranging from (721-770) kg/m3 and thermalconductivity ranging from (0.17- 0.24) W/ (m.K). The good correlation betweenaccelerated compressive strength at one day with normal compressive strength at 28-day is approximately (0.245 ±0.005) for water bath at 55°C and (0.335±0.05) forwater bath at 82°C.


Article
Strength Evaluation of CO2-Cured Cellulose Date Palm Fiber Reinforced Cementitious Boards

Authors: Maan Salman Hassan --- Shakir Ahmed Salih --- Isam Mohamad Ali
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 6 Part (A) Engineering Pages: 1029-1046
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In recent years there has been an increasing demand to recycle wastes produced by the agricultural and industrial processing. The aim of this paper is to investigate the suitability of date palm (Phoenix dactylifera) as lignocellulosic materials for the production of wood-cement composite boards, in addition to enhance their compatibility with cement using physical pretreatment processes and accelerated carbonation curing. Experiments were performed to assess the physical properties (as density, flexural strength, toughness and E-modulus), and micro structural properties (as determined by scanning electron microscopy) of the produced cement boards. The results show an improvement in the physical and microstructural properties of cellulosic fiber-cement composites by using accelerated CO2 curing method. In addition, excessive carbonation rate associated with pure gas carbonation does not necessarily lead to high strength and even detrimental strength development was found, which was shown by cement paste.


Article
Some Properties of Superplasticized and Retarding Concrete Under Effect of Accelerated Curing Methods

Author: Dalia Shakir Atwan
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2012 Volume: 18 Issue: 5 Pages: 539-551
Publisher: Baghdad University جامعة بغداد

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Abstract

In recent decades, tremendous success has been achieved in the advancement of chemical admixtures for Portland cement concrete. Most efforts have concentrated on improving the properties of concrete and studying the factors that influence on these properties. Since the compressive strength is considered a valuable property and is invariably a vital element of the structural design, especially high early strength development which can be provide more benefits in concrete production, such as reducing construction time and labor and saving the formwork and energy. As a matter of fact, it is influenced as a most properties of concrete by several factors including water-cement ratio, cement type and curing methods employed. Because of accelerated curing is deemed one of methods that achieved high early age strength of concrete and has been grown only gradually. So, the prime aim of this research work is to provide information about the some desired properties of superplasticized and retarding concrete succumbed to accelerated curing methods, such as compressive strength and water absorption and compared it with their corresponding normally curing concrete. Besides, the research discusses the influence of surface texture of aggregate and over-dosing for admixture on performance concrete in such as that conditions. The test results revealed that effect of admixture on properties of concrete are dependent upon it dosage, surface texture for aggregate and temperature used for curing.

في العقود الاخيرة تحققت الكثير من النجاحات فيما يخص تطوير المضافات الكيميائية لخرسانة السمنت البورتلاندي. واغلب الجهود تركزت على تحسين خصائص الخرسانة وايضا دراسة العوامل المؤثرة عليها. وبما ان مقاومة الانضغاط تعتبر الخاصية القيمّة والعامل الاساس والثابت في التصميم الانشائي خصوصا تطورها في الاعمار المبكرة حيث يمكن ان توفر العديد من الفوائد في انتاج الخرسانة مثل تقليل مدة وعمل البناء و توفير القوالب. الا انها في واقع الامر كمعظم خصائص الخرسانة تتأثر بعدة عوامل بضمنها نسبة الماء الى السمنت,نوع السمنت وطرق الانضاج المتبعة. ولكون الانضاج المعجل يعتبر احد الطرق التي تحقق مقاومة عالية ومبكرة للخرسانة واصبحت تنمو بشكل تدريجي. لذا كان الهدف الرئيسي للبحث هو توفير معلومات عن بعض الخصائص المرغوبة لخرسانة الملدن المتفوق والمبطيئ والخاضعة لتاثير الانضاج المعجل مثل مقاومة الانضغاط وامتصاص الماء ومقارنتها مع خصائص الخرسانة في حالة الانضاج الاعتيادي. بجانب ذلك, يناقش البحث تاثير الملمس السطحي للركام الخشن والوزمات العالية للمضاف على اداء الخرسانة في مثل تلك الظروف. وأظهرت نتائج البحث بأن تأثير المضاف على خصائص الخرسانة يعتمد على وزمة المضاف,الملمس السطحي للركام ودرجة الحرارة المستخدمة للانضاج.

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