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Article
Effect of Plastic Fibers on Properties of Foamed Concrete
تأثير الألياف البلاستيكية على خواص الخرسانة الرغوية و الخفيفة الوزن

Authors: Hisham K. Ahmed --- Waleed A. Abbas --- DohaM. Abdul-Razzaq
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 7 Part (A) Engineering Pages: 1313-1330
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The main objective of this work is to study the effect of adding plastic fibers on Lightweight Aggregate Foamed Concrete (LWAFC) using mix proportion of 1:2.6:0.4 by volume (cement: fine Porcelanite: coarse Porcelanite) with 2% foaming agent by weight of water, and using sand as a partial and total replacement of local Porcelanite aggregate in that mix. The properties of lightweight aggregate foamed concrete reinforced with different percentages of plastic fiber (0.5, 0.75, and 1% by volume) were studied. Compressive strength, splitting tensile strength, flexural strength, dry density, initial surface absorption, water absorption, ultrasonic pulse velocity, acoustic impedance, and impact resistance tests were conducted on mixes at ages of 7, 28, and 60 days. The results showed a significant increasing in impact resistance, splitting tensile strength, and water absorption 34.55%, 4.2%, 326%, and 27.3% respectively. While the results indicated that the compressive strength, ultrasonic pulse velocity, dry density and acoustic impedance of the composites were reduced when the crimped plastic fiber volume fraction increases. The percentage of reduction of these properties was 15%, 11.1%, 6.23%, and 12.55% respectively.

إن الهدف الرئيسي لهذا البحث هو دراسة تأثير إضافة الالياف البلاستيكية على الخرسانة الرغوية الخفيفة الوزن باستعمال نسب خلط حجمية 1 ، 2.6 ، 0.4 (سمنت : بورسيلانايت ناعم : بورسيلانايت خشن) وباضافة 2% من المادة الرغوية كنسبة وزنية من الماء وباحلال الرمل كبديل جزئي أو كلي من ركام البورسيلانايت المحلي في الخلطة. تمت دراسة استعمال الالياف البلاستيكية بنسب حجمية مختلفة ( 0.5 ، 0.75 ، 1.0% ) لتسليح الخرسانة الرغوية الخفيفة الوزن. تم إجراءفحوصات مقاومة الانضغاط و مقاومة الشد و فحص الانثناء و مقاومة الصدم والكثافة الجافة و الامتصاص السطحي الاولي و الامتصاص الكلي وسرعة الذبذبات الفوق الصوتية والمعاوقة الصوتية للخلطات بأعمار 60،28،7 يوماً. بينت النتائج زيادة ملحوظة في مقاومة الصدم و مقاومة شد الانفلاق و امتصاص الماء و التي بلغت 34.55% , 4.2%, 27.3% على التوالي مع زيادة محتوى الالياف على الرغم من تسجيل انخفاض في مقاومة الانضغاط و الذبذبات فوق الصوتية و الكثافة الجافة و المعاوقة الصوتية مع زيادة محتوى الالياف. وقد بلغ مقدار الأنخفاض في هذه الخصائص 15%, 11.1%, 6.23%, 12.55% على التوالي.


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


Article
Behavior of High Strength Concrete Containing Nano- Metakaolin Exposure to Fire Flame

Authors: Mohammed K. Al-Khafaji --- Waleed A. Abbas --- Shakir Al-Mishhadani
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 5 Part (A) Engineering Pages: 857-875
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The aim of this experimental study was to evaluate the effect of fire flame exposure with different intensities of firing on the mechanical properties of a high strength concrete (HSC). Many variables were encountered in this study. Two mixes of 80 MPa target compressive strength (1:1.22:2) with 3% Nano-Metakaolin and the other with 5% were used. Two types of coarse aggregate were used (natural crushed gravel and crushed dolomite rock with maximum size of 14mm). The specimens were moist cured for 28 days, air-dried in the laboratory to firing at ages 90 days at three temperature levels (400, 600, 800)oC and for three exposure periods (1, 1.5 and 2 hours). Different methods were used to cool specimens. The reduction values of compressive strength for all mixes ranged between (2-69.5)% at 400oC, (8-72)% at 600oC and (10-85)% at 800oC , the reduction values of splitting tensile strength were (9-43.2)%, (17-50)% and (39-76)%, and the reduction values of flexural strength were (51.7-84.8)%, (52.8-87) %, (53.6-87.8)%, respectively.

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Article
Fresh and Hardened Properties ofLightweight Self CompactingConcrete Containing Attapulgite

Authors: Waleed A. Abbas --- Qais J.Frayyeh --- Shubbar J. Al Obaidey
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 9 Part (A) Engineering Pages: 1767-1781
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The main objectives of this study were investigating the possibility of producing lightweight self -Compacting concrete (LWSCC) by using artificial coarse lightweight aggregate manufactured by burning locally available Attapulgite clay, estimating the optimum dosage of high reactivity Attapulgite (HRA) and studying its effects on fresh and hardened properties of LWSCC when using it as a partial replacement by weight of cement.Tests results showed that, It is possible to produce (LWSCC) by using Attapulgite as artificial coarse (LWA) and (HRA).The optimum content for (HRA) used in this study was 10 %, the percentages of increment in compressive strength and splitting tensile strength with 10% (HRA) relative to reference mix were (10.0%, 12.1%, 11.1% and 12.4%) and ( 12.0%, 18.2%, 16.6% and 16.2%) for 7, 28, 56 and 90 days respectively.The values of the calculated equilibrium density ranged between (1788 and 1829) kg/m3


Article
The Combined Effect of Attapulgite High Reactive Mineral Admixture and Superplastisizer on Compressive Strength of Attapulgite Lightweight Aggregate Concrete

Authors: Qais J. Frayyeh --- Waleed A. Abbas --- Ali K. Hassan
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 12 Part (A) Engineering Pages: 2181-2192
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The goal of this study , mainly is to investigate thecombined effects of using both Attapulgite high reactive mineral admixture and superplastisizer on the compressive strength of Attapulgite lightweight aggregate concrete ALWAC and some properties of sconcrete . The used coarse lightweight aggregate was made from Attapulgite clays with maximum size of 19 mm , and the optimum percentages of addition for both mineral and chemical admixture was 6% partial replacement from cement for Attapulgite mineral admixture and 0.5 L/100 kg cement for the superplastisizer used .The gained percentages of enhancement for compressive strength was (12.2%,12.6% and 16.3%) for curing ages of 7, 28 and 56 respectively as compared with the referenced plane mix when only the Attapulgite mineral admixture to be added , while the combined effect of both admixtures was clear by the percentages of ( 19.3% , 15.5% and 25% ) for curing ages 7,28 and 56 respectively as compared to the plane referenced mix . The obtained equilibrium density of ALWAC was 1818 kg/m3 ( ACI 213r-03 , less than 1840 kg/ m3 for structural purposes)for the concrete mix containing the two admixtures . The water absorption of ALWAC was reduced by the addition of the Attapulgite mineral admixture by (4% , 4.85% and 4.9% ) at 7,28 and 56 days of curing respectively but, using the superplastisizer cause an increase in water absorption and the percentages above get lowered to (2% , 3% and 2.6% ) at the ages of 7,28 and 56 days respectively .


Article
PUNCHING SHEAR BEHAVIOR OF THREE DIMENSION TEXTILES REINFORCED CEMENTITIOUS COMPOSITE PLATES

Authors: Nadia Moneem --- Waleed A. Abbas --- Ikbal N. Gorgis
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2018 Volume: 9 Issue: 4 Pages: 45-64
Publisher: University of Kufa جامعة الكوفة

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Abstract

Self compacting mortars (SCMs) plate specimens with dimension of (500×500×40) mm were cast with three-dimension (3D) textile glass fiber having three diverse thicknesses 6, 10, and 15mm to measure their punching strength. Plates with one and two layers of chicken wires, as well as micro steel fiber of 0.75 % volume fraction were tested under punching for comparison. Punching shear tests have been carried out by applying concentrated load with steel cylinder of 50mm diameter and 10 mm height. The mechanical behavior of SCMs plate was discussed in terms of observed behavior, ultimate load, load - deflection curves, and crack pattern. The results indicated an enhancement in the ultimate load at (28 and 90) day ages by about (7.82% and 24%), respectively. The maximum ultimate load was increased by about (58.4 and 54.1) % for plates reinforced by micro steel fiber at 28 and 90 days, respectively as compared with reference. The maximum deflection at the center of the Self-compact mortars plates for all tested plates was improved.


Article
Impact Strength for the 3D Textiles Fiber Reinforced Cementitious Composites Plates
تحمل الصدمة للصفائح السمنتية المركبة والمسلحة بنسيج زجاجي ثلاثي الابعاد

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Abstract

The use of textile reinforcement made from non-corrosive materials, such as carbon and glass can reduce the required concrete material; this is known as Textile Reinforced Concrete (TRC). This study deals with plate specimens having dimension of 500×500×40mm tested under impact load at 28 and 90 days age under two conditions of ends, simply supported and fixed. Cement mortar with about 60 MPa, 7cm cube compressive strength at 28 days was designed for casting the plates. Plate specimens were divided into four groups, they consist of reference plates (no reinforcement) and plates reinforced with 3D glass fabric having three different thicknesses 6, 10 and 15mm.The results indicate that using 3D textile glass fabric cause an increase in number of blows, reduce in final stage deflection, an improvement in toughness and energy absorption under impact loads. Using 3D textile glass fiber with 10mm thickness gave higher number of blows for 28 and 90 days as compared with 6 and 15 mm. Plates with slice 6mm 3D textile glass fiber in two way reinforced has significantly enhancement in number of blows, the improvement was about (80 - 125%) and (128.5- 114. 3%) for 28 and 90 days respectively. The specimens showed increase in the energy absorption, besides the number and width of cracks was reduced and only few cracks are propagated up to the edge of the plates.

ان استخدام الالياف اوالنسيج بابعاد ثلاثية مصنوعة من مواد زجاجية اوكاربونية ذات طبيعة كيميائية خاملة يؤدي الى تقليل بكمية المواد السمنتية الداخلة بالخلطة الخرسانية. حيث تضمنت هذه الدراسة قياس تحمل الصدمة لصفائح بابعاد 500*500*40 ملم وبعمر 28 و90 يوم بواقع نوعين من الشروط الحدودية (بسيطة وثابتة). وتم صب الصفائح باستخدام مونة اسمنتية ذات مقاومة انضغاط 60 ميكاباسكال بعمر 28 يوم. قسمت الصفائح الى اربع مجاميع مؤلفة من صفائح بدون استخدام اي الياف لغرض المقارنة وصفائح مسلحة بثلاث اسماك مختلفة (6و10و15ملم) من الياف زجاجية ثلاثية الابعاد. فحصت الصفائح تحت تاثير حمل الصدمة واظهرت النتائج ان استخدام نسيج زجاجي ثلاثي الابعاد ادى الى تحسن في خواص الصفائح وذلك بزيادة عدد الضربات وتقليل الانحرافات وزيادة في مقدار الطاقة الممتصة. ان استخدام الياف زجاجية بسمك 10 ملم تطلب زيادة في عدد الضربات المطلوبة للفشل بعمر فحص 28 و90 يوم مقارنة مع سمك 6 و15 ملم. كما ان استخدام نسيج ثلاثي الابعاد على شكل شراح بطبقتين وبسمك 6 ملم ابدى قوى ربط اكبر وتحسن بعدد الضربات ، حيث كان التحسن بمقدار 80-128 % و128.5-114.3% لاعمار 28 و90 يوم اضافة الى ان جميع الصفائح اظهرت زيادة في امتصاص الطاقة ونقصان في سمك وعدد الشقوق خلال الفحص .

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