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Article
Behavior of Plain and High Performance Polypropylene Fiber Concrete Subjected to Elevated Temperatures

Author: Luma Abdul Ghani Zghair
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 8 Pages: 1517-1535
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The aim of this work is to determine the residual compressive strength and splitting tensile strength after exposure to an elevated temperature (between100 to 500 C ◌ْ ) of plain and polypropylene fiber reinforced concrete (PPFRC) in comparison with specimens exposed to ordinary temperature 25C ◌ْ . High – performance concrete mixes were produced by using high rang reducing agent superplasticizer (SP) and 10% high reactivity metakaoline (HRM) as a partial replacement by weight of cement (350)Kg/m3 . A single concrete mix with HRM,SP and four PPF contents of (0.25, o.5, o.75 and 1%) by volume were adopted. The workability of the concrete was kept constant ( slump 100 ± 5mm ).Each group of specimens ( plain and PPFRC ) was heated to a specified temperature and kept at the temperature for one hour before being gradually cooled to room temperature and then they were tested .The results show at ordinary temperatures 25 C ◌ْ, the addition of fiber volume fraction (VF%) of (0.25%) increases the compressive ( 20.6% ) comparable to HPC without fiber . While the addition of ( 0.5 , 0.75 and 1% ) of polymer fibers , the compressive strength decreased (12.6 , 19 and 33%) respectively comparable to HPC without fiber . On the other hand the addition of (VF%) of (0.25) increased splitting tensile strength ( 15%) comparable to HPC without fiber . while theaddition of fiber volume fraction (VF%) of (0.5 ) increased splitting tensile strength by a percentage which is lower than that in specimens with VF% of 0.25 , the increase in splitting tensile strength was ( 6%) comparable to HPC without fiber at ordinary temperaturesThe results also shows that , when (1% ) fibers was used , the splitting tensile strength decreased ( 10.8%) in comparable to HPC without fiber At elevated temperature the results show an appreciable decrease in compressive strength and splitting tensile strength after exposure to temperature higher than 300 C ◌ْ of both plain and PPFRCSpecimens containing PPF ( 0.25 , 0.5 , and 0.75 %) the percentage ofreduction in splitting tensile strength is lower than that in HPC specimens ( without fibers ) after exposure to a temperature ( 500 ,300 and 100 C ◌ْ ) comparable to normal temperature 25C ◌ْ .While specimen containing PPF ( 1% ) the percentage of reduction in splitting tensile strength was higher than specimen without PPF after exposure to a similar temperature .On the other hand , specimens containing PPF ( 0.25 , 0.5 , 0.75 and 1 %) the percentage of reduction in compressive strength is higher than that in HPC specimens ( without fibers ) after exposure to a temperature (500 ,300 and 100 C ◌ْ). comparable to normal temperature 25C ◌ْ


Article
The Effect of Coarse Aggregate Ratio on the Properties of No Fine Light Weight Concrete
تاثير نسبة الركام الخشن على خواص الخرسانة الخالية من الركام الناعم

Authors: Luma Abdul. Ghani. Zghair --- Hind.H. HAMAD
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2009 Volume: 15 Issue: 4 Pages: 4447 -4462
Publisher: Baghdad University جامعة بغداد

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Abstract

The main object of this work is to study the effect of coarse aggregate/cement ratio (A/C) on the property of no fine concrete. In this work, three ratio of A/C were used (6, 9 and 12 by weight).The cement content is maintained constant (125kg/m3) while the w/c ratio ranges from (0.39 to 0.55 by weight). Tests are carried out on hardened concrete to investigate the effect of coarse aggregate/cement ratio on the compressive strength, absorption%, density, porosity%, ultrasonic pulse velocity, acoustic impedance of mixes.The results showed that increasing the percentage of A/C ratio by weight from 6 to 12 for the used mixes reduces the compressive strength, ultrasonic pulse velocity and acoustic impedance, on the other hand the porosity and the absorption percentage, increase with increasing ratio of A/C for all studied mixes.At 28 days the compressive strength , ultrasonic pulse velocity and acoustic impedance tests with A/C ratio of (12) are (2.8.MPa), (2km/sec) and (3×106 Kg/(sec.m2)) respectively while decreasing the ratio to (6) improves these properties to (9.3MPa), (3km/sec) and ( 5.7 ×106 Kg/(sec.m2)) respectively On the other hand the porosity and the absorption % decrease with decreasing the ratio of A/C for all studied mixes . At 28 days the porosity and the absorption % with A/C ratio of (12) are (40%) and (2.7%) respectively with decreasing the ratio to 6 decrease these properties to (19%) and (1%) respectively. The densities of the mixes were tested. At 28 days the density with A/C ratio of (12) are (1512 kg/m3 )with decreasing the ratio to 6 increase the density to(1907 kg/m3 ) Based on the analysis of experimental results, several graphs and tables have been prepared to study the properties of no fine concrete.

الهدف الأساسي لهذا العمل هو دراسة تاثيرنسبة الركام الخشن/ السمنت ( A/C ) على خواص الخرسانة الخالية من الركام الناعم . تم استخدام ثلاثة نسب وزنية من (6,9و12) ، (A/C) محتوى السمنت ثابتاً( 125 كغم/م3) بينما نسبة الماء / السمنت تتراوح بين ( 0.39 الى 0.55) اختير اجراءالفحوصات على الخرسانة المتصلبة لدراسة تاثيرنسبة الركام الخشن/ السمنت على مقاومة الانضغاط ، نسبة الامتصاص ، الكثافة ، المسامية ، فحص الموجات الصوتية و فحص المعاوقة الصوتية .النتائج اظهرت ان زيادة نسبة ( A/C ) من 6 الى 12وزنيا" ادى الى نقصان في مقاومة الانضغاط ، فحص الموجات الصوتية و فحص المعاوقة الصوتية من الناحية الاخرى المسامية و نسبة الامتصاص قد ازدادت عند زيادة نسبة ( A/C ) للخلطات الخرسانية.في عمر 28 يوم مقاومة الانضغاط ، فحص الموجات الصوتية و فحص المعاوقة الصوتية عند نسبة (A/C ) (12) كانت(2.8 ميكاباسكال)،(2كم/ثا) و 3 ×6^10 (كغم/(ثا . م2 ) ) على التوالي بينما نقصان النسبة الى( 6) ادى الى تحسين الخواص السابقة (9.3 ميكاباسكال)، ( 3كم/ثا) و( 5.7 ×6^10 )كغم/(ثا . م2 ) ) على التوالي و من الجانب الاخر المسامية و نسبة الامتصاص قلت مع تقليل نسبة ( A/C ) للخلطات الخرسانية.في عمر 28 يوم المسامية و نسبة الامتصاص عند نسبة ( A/C ) (12) كانت(40%) و 2.7%) (على التوالي بينما نقصان النسبة الى( 6) ادى الى تقليل تلك الخواص الى (19%) و(1%) .تم فحص الكثافة للخلطات الخرسانية في عمر 28 يوم عند نسبة (A/C ) (12) وكانت ( 1512 كغ/م3) بينما نقصان النسبة الى( 6) ادى الى زيادة في الكثافة الى (1907كغ/م3)، اعتمادا على تحليل النتائج مختبريا ، بضع رسومات و جداول اعدت لدراسة خواص الخرسانة الخالية من الركام الناعم.


Article
BEHAVIOR OF SELF COMPACTING CONCRETE SUBJECTED TO SULPHURIC ACID
سلوك الخرسانة الذاتية الرص المعرضة الى حامض الكبريتيك

Authors: Mohammed Mosleh Salman --- Luma Abdul Ghani Zghair
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 5 Pages: 1-9
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Self-Compacting Concrete mixes (SCC) is increasingly being used in many application some of which are susceptible to an Aggressive Environment such as sulfuric acid solution. In this study SCC incorporating silica fume, chalk powder and hybrid fibers were used in casting twelve specimens with a dimensions of (1000× 200× 100) mm , in three groups. The specimens in the first group were cured in normal environment for 28 days, while those in the second and third groups were subjected to sulfuric acid solution of 0.5% for six and ten months, respectively. The flexural tests of the specimens were evaluated by testing the specimens under two-concentrated point loading until failure. The experimental results show that after chemical exposure for ten months, using of chalk powder or hybrid fibers enhances the resistance to sulfuric solution


Article
Influence of Fine Aggregate Grading on Some Properties of Self – Compacting Concrete
تاثير تدرج الركام الناعم على بعض خواص الخرسانة ذاتية الرص

Author: Luma Abdul Ghani Zghair لمى عبد الغني زغير
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2010 Volume: 14 Issue: 3 Pages: 18-37
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Self compacting concrete ( SCC ) can be classified as high – performance concrete .It does not require to be vibrated to achieve full compaction. This offers many benefits and advantages over conventional concrete. The main object of this work was to investigate the properties of SCC produced by locally available materials and to evaluate the effect of grading of fine aggregate ( Coarse Grading CG , Medium Grading MG and Fine Grading FG ) with fineness modulus ranging from (1.9 to 2.7) on some properties of SCC .To achieve this aim, three different mixes of SCC were designed and tested . The used cement content was ( 350 kg/m3) , the powder content material ( cement + limestone dust) maintained constant (500 kg/m3 ) and the water/powder content ratio was ( 0.34). To determine the workability , different test methods were adopted as slump flow , J-ring and L –box tests . It is found the workability of all studied mixes is good, with slump flow diameter greater than or equal to (600 mm), flow times range between (3 and 7.5)sec. while the step of blocking ranges between (0 and 1)mm. The mechanical properties of hardened SCC mixes are also assessed. (compressive strength, splitting tensile strength , modulus of rupture , static modulus of elasticity, and density ) . The results of this study show the possibility of using different grading of fine aggregate with fineness modulus ranging from ( 1.9 to 2.7 ) to produce SCC . The grading pf fine aggregate has a significant effect on fresh properties of SCC while it has insignificant effect on mechanical properties of SCC.

يمكن تصنيف خرسانة الرص الذاتي على انها خرسنة عالية الاداء . ان هذا النوع من الخرسانة لا يحتاج الى الرج للوصول الى حالة الرص التام ، مما يوفر عد فوائد و مزايا تتفوق على الخرسانة الاعتيادية الهدف الرئيسي من هذا البحث هو لدراسة خواص الخرسانة الذاتية الرص المنتجة من مواد متوفرة محليا " و تقييم تاثير تدرج الركام الناعم ( تدرج خشن ، تدرج متوسط ، تدرج ناعم) مع معامل نعومة تتراوح بين ( 1.9 – 2.7 ) على خصائص الخرسانة الذاتية الرص . و لتحقيق هذا الهدف ، تم تصميم و فحص ثلاثة خلطات مختلفة من الخرسانة الذاتية الرص ، نسب محتوى السمنت التي استعملت هي ( 350 كغمم3 ) ، محتوى مادة المسحوق ( سمنت + الغبرة ) كانت (500 كغمم3 ) و نسبة محتوى المسحوق الى الماء كان (0.34 ) . الفحوصات المختبرية التي استخدمت لايجاد قابلية التشغيل هي فحص جريان الهطول باستخدام االقمع و الشكل ( J) و فحص الصندوق على شكل ( (L . قابلية تشغيل الخلطات الخرسانية كانت جيدة حيث كانت انتشار الخرسانة كانت اكثراو يساوي 650 ملم ، زمن الجريان يتراوح بين ( 2.8 و7.5 ثانية) بينما درجة حجز الخرسانة بين( 0 الى 15 ملم ) . ان الخصائص الميكانيكية التي تم درساتها في هذا البحث هي ( مقاومة الانضغاط ، مقاومة الانشطار ، مقاومة الشد بالكسر ، معامل المرونة و الكثافة ) . النتائج اضهرت امكانية استعمال تدرج مختلف من الركام الناعم مع معامل نعومة تتراوح بين ( 1.9 – 2.7 ) في انتاج خرسانة ذاتية الرص و تاثير التغير في تدرج الركام الناعم ليس واضحا" على الخرسانة المتصلبة ، بينما كانت اكثر وضوحا" على الخرسانة الطرية .

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