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Article
Effect of Waiting Time before Re-vibration on Mechanical Properties of Fiber Reinforced Concrete

Author: Aseel A. Abdulridha
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 7 Part (A) Engineering Pages: 748-758
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

A knowledge of the concrete vibration after casting have led to improve the mechanical properties of concrete, reduce the deformations due to creep and shrinkage and reduce the concrete permeability. At the Structural and Material Laboratories- Building and Construction Engineering Department, University of Technology, series experimental tests on prisms, cubes and cylinders were carried out to investigate the effect of waiting time after initial vibration on the flexural-tensile strength, compressive strength and splitting tensile strength of fiber reinforced concrete. The variables considered in this study were; the amount of steel fiber and waiting time after initial vibration. The test results showed that the concrete prisms without steel fiber show approximately linear behavior till the maximum flexural-tensile load due to brittle behavior of concrete. The maximum improvement in flexural-tensile strength of concrete prism occurs after the initial setting of concrete i.e after 90 minutes of waiting time. The re-vibration after time period increase the stiffness of concrete prism in case of presence of steel fiber compared with the prisms initially vibrated only. The modulus of rupture of concrete prism increased with the increasing of steel fiber content for all waiting time before re-vibration.


Article
Improving the Mechanical Properties of Lightweight Foamed Concrete Using Silica Fume and Steel Fibers

Authors: Suhad M. Abd --- Dhamyaa Ghalib
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2018 Volume: 21 Issue: 2 Pages: 300-307
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

Lightweight foamed concrete (LWFC) is characterized as a light in self-weight, self- compacting, self-levelling, and thermal and sound isolation. But it has low strength and low ductility which leads that the application of (LWFC) in the building construction is limited. The flowability of the fresh mix of (LWFC) was evaluated by flow test. While the hardened properties of (LWFC) include, compressive 6 strength, tensile6 splitting6 strength, flexural 6 strength, and 6modulus of 6 elasticity. This 6 study6 focuses6 on the effect of the adding of silica fume and steel fibre on the mechanical properties of (LWFC). Silica fume was added as (5%) and (10%) by the weight of cement and steel fiber (0.2%) and (0.4%) of the total volume of the mix. The density of lightweight foamed concrete was 1800±50kg/�3, and cement to sand ratio was (1:1) with water cement ratio (0.28). The results indicated that adding of silica fume6 and steel 6 fiber 6 have great effect on the mechanical properties and improve them. The addition (10%) of silica fume and (0.4%) by volume of steel fiber was the best ratio that improves the mechanical properties of the lightweight foamed concrete (LWFC). The pozzolanic index of the (5%) and (10%) silica fume was (21.9%) and (74.76%), respectively.


Article
EFFECT OF STEEL FIBERS RATIO ON THE STRUCTURAL BEHAVIOR OF DOMES
تأثير نسبة الألياف الفولاذية على السلوك الهيكلي للقباب

Authors: Mohammed Mohammed Rasheed --- Layth Abdulbari Al-Jaberi --- Nadiyah Kherallah Abd
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 5 Pages: 118-129
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The main objective of the current paper is to investigate the effects of the ratio of steel fibers on structural behavior of reinforced concrete hemispherical domes. Three reinforced concrete domes were experimentally implemented, two of them made fully of reactive powder concrete and the last one made of ferrocement concrete. All specimens have 800 mm diameter, 400 mm height and 20 mm thickness, and they reinforced with welded wire meshes. The experimental program included casting and testing the domes, by applied a single point load at the center of dome, until the failure is happened. The first cracking load, ultimate load, load deflection curves, and crack pattern for all tested domes were included in this study. In general, the effects of concrete type and the ratio of steel fiber are obviously important on the behavior and ultimate strength of the domes.


Article
FLEXURAL BEHAVIOR OF SLURRY INFILTRATED FIBER CONCRETE (SIFCON) CONTAINING SUPPLEMENTARY CEMENTITIOUSE MATERIALS

Authors: Shakir Ahmed Salih --- Qais Jwad Frayyeh --- Manolia Abed Al-wahab Ali
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 2 (Part-3) Pages: 35-48
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Slurry Infiltrated fiber Concrete (SIFCON) is a relatively new high performance material and can be considered as a special type of Fiber Reinforced Concrete (FRC) with high fiber content. The matrix consists of flowing mortar or cement slurry which must infiltrate properly through the fiber network placed in molds. SIFCON possessing excellent mechanical properties coupled with large ductility and toughness values. SIFCON has found application in area where high ductility and energy absorption are needed especially in seismic-resistant reinforced concrete frames and in structure under abnormal or explosive loads. Other successful applications include pavement overlays, repair of prestressed beams and repair of structural reinforced concrete element.The main aim of this study is to determine the effect of hooked ended steel fiber content and mineral admixture replacement silica fume (SF) on strength and deformation characteristics of SIFCON specimens under flexural loading. Three volume fraction of steel fiber (6, 8.5, and 11) % were used in this investigation .The percentage of SF replacement was (10%), by weight of cement in SIFCON slurry. Both the flexural strength and toughness characteristic were carried out by testing specimens of 100*100*400 mm at the age of 7and 28 days. The results obtained from these tests were compared with those carried out on conventional fiber reinforced mortar (FRM) with 2% fiber content, as control specimens. The test results show superior characteristics of SIFCON ,as compared with normal FRM ,which were affected in positive manner by using cementitiouse materials (SF) as a partial replacement by weight of cement, and with increasing the volume fraction of steel fiber. The flexural strength and toughness value up to (28.08 MPa ) and (159 N.mm),respectively were obtained at age of 28 days.


Article
Steel Fiber Reinforced Self-Compact Concrete Beam under Static Loading Using Finite Elements Method
العتبات الخرسانية ذاتية الرص والمعززة بالياف حديدية تحت تاثير الاحمال الساكنة باستخدام طريقة العناصر المحددة

Author: Sura Amoori Abbas
Journal: journal of kerbala university مجلة جامعة كربلاء ISSN: 18130410 Year: 2018 Volume: 16 Issue: 1 Pages: 372-387
Publisher: Kerbala University جامعة كربلاء

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Abstract

Static resistance loading of reinforced concrete beams using normal and steel fiber self-compact concrete, with loading applied at the one – third of the beam (four points) was studied. The reinforced concrete beams have been designed under static load according to ACI-318R-2014 [1]. The static loading consists of dead load and residential live load based on ASCE-07-2010 [2].as the beam a part from residential building that scaled down and modeled to not at full scale but as like the traditional experimental test. A three-dimensional finite element models by ANSYS15.0 software [3], have been established to provide a numerical solution as an alternative approach to the experimental models, with some acceptable accuracy. Experimental tests for normal, self – compact and with and without steel fiber concrete to specify compressive strength, tensile strength, and modulus of elasticity presented. Modeling analysis as simply supported beams as approximate situation of beam that was performed to evaluate the performance of ordinary, self-compact and steel fiber self-compact concrete beams under static loading.

تمت دراسة تحميل المقاومة الساكنة للعتبات الخرسانية المسلحة مستخدماً الخرسانة الاعتيادية وذات الالياف الحديدية ذاتية الرص , مع وبدون الالياف الحديدية تحت تأثير التحميل الساكن (أربع نقاط). صممت العتبات الخرسانية المسلحة تحت تأثير الحمل الساكن وفقا للمدونة الآمريكية ACI-318R-2014 . الحمل الساكن يتضمن الحمل الميت والحمل الحي معتمداً المواصفة ASCE-07-2010 بأفتراض ان العتبة هي جزء من مبنى سكني تم تصغيره وليس أخذه بالقياسات الحقيقية بما يتلائم مع الفحوصات العملية التقليدية المماثلة.تم إنشاء نماذج العناصر المحدودة ثلاثية الأبعاد باستخدام برنامج ِANSYS اصدار (15) كحل لتوفير حل عددي كنهج بديل للطرق التجريبية، مع بعض الدقة المقبولة. تم اجراء الاختبارات التجريبية للخرسانة الاعتيادية والخرسانة الذاتية الرص المعززة وغير المعززة بألياف الحديد لتحديد قوة الانضغاط، قوة الشد، ومعامل المرونة. تم إجراء تحليل النمذجة على شكل عتبات مدعمة باسناد بسيط وهذا تقريب للحالة الحقيقية لتقييم أداء العتبات الخرسانية الانفة الذكر.


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
Behavior of Cantilever Beams in R.C. Frames with Effect of Steel Fibers in Beam – Column Joint

Author: Mohanad Salih Farhan مهند صالح فرحان
Journal: DIYALA JOURNAL OF ENGINEERING SCIENCES مجلة ديالى للعلوم الهندسية ISSN: 19998716/26166909 Year: 2018 Volume: 11 Issue: 4 Pages: 14-19
Publisher: Diyala University جامعة ديالى

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Abstract

This paper aims at investigating the behavior of cantilever beam in reinforced concrete frame modified by steel fibers. The study depends on adding steel fibers at the joint of beam column section to improves the ductility of the beam – column joint. Steel fibers of ratio (0.5%) and (1%) steel fibers by volume added for two specimens comparing with two others cast without steel fibers joint in R.C. frame. The cantilever frame behavior at applied load will be discussed in this study. The load applied to the frame at the edge of cantilever arms. The test results showed that the difference between the monolithic frame is larger in ultimate loads compared with non-monolithic, and the frame with 1% steel fibers have large load capacity compared with 0.5% steel fibers frame. The frame which cast monolithically shows highest resistance among the three other frames in ultimate load and flexural deformation, after load was applied to the four specimens the behavior of the frame up to the failure occurred in the beam-column joint at exterior face of the cantilever. beside studying the effect of steel fibers percentage and behavior of beam column joint, this study focuses also on investigating the difference between monolithic and non-monolithic concrete elements.


Article
BOND STRENGTH OF LIGHT-WEIGHT CONCRETE PULL-OUT SPECIMENS CONTAIN STEEL FIBERS

Authors: Aamer Najim Abbas --- Lina Abdulsalam Shihab --- Yaqoob Talib Yaqoob
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 2 (Part-2) Pages: 123-133
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Bond between reinforcing steel bar and concrete has a critical influence on the structural behavior of reinforced concrete members. The nature of the concrete makes the bond characteristics inherently variable. The variability of the bond affects some of the more practical parameters such as the embedded length, bar diameter and cover thickness, which, in turn, considerably influence the length of the reinforcing elements used in the fabrication of the composite. In this investigation, the bond strength of normal weight, lightweight and fibrous lightweight concretes are investigated by use pull-out test results. The embedded lengths, bar diameter and cover thickness are taken as variables. The experimental work indicated that steel fibers specimens exhibited increase in bond strength about (75.45%), (126.36%) and (174.54%) when using (0.5%), (1%) and (1.5%) of total volume steel fibers respectively. Also, the specimens that are poured with (16mm) bar diameter have bond strength lower than that of small bar diameter for two types of concrete. In all concrete specimens, the specimens with large embedded length and concrete cover tend to fail by bond strength higher than that of small embedded length and concrete cover.


Article
Flexural Performance of Hybrid Fiber Reinforced Cement Composites Under Elevated Temperatures
أداء االنثناء لل لواح اإلسمنتية المسلحة باأللياف الهجينة تحت تأثير درجات الحرارة العالية

Authors: Isam Mohamad Ali عصام محمد علي --- Ali Hadi Adheem علي هادي عظيم
Journal: Muthanna Journal of Engineering and Technology(MJET) مجلة المثنى للهندسة والتكنولوجيا ISSN: 25720317 25720325 Year: 2018 Volume: 6 Issue: 2 Pages: 113-119
Publisher: Al-Muthanna University جامعة المثنى

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Abstract

Historically, the flexural behavior of hybrid fiber cement composites is not completely understood using the traditional test methods. This research presents the results of an experimental investigations on a high performance cement composites (HPCC) containing both micro steel fibers (SF) and micro polypropylene fibers (PP) before and after elevated temperature exposure. The experimental program was developed to study the flexural performance (flexural strength, toughness and stiffness) under high temperature using mono and hybrid (SF) and (SF + PP) fibers. Mixtures were divided into eight different groups, with constant w/c of 0.28 and different fibers content.Based on the results of this research, the replacing of micro (SF) in high performance cement composites by 15 % of micro (PP) fibers is recommended at high temperature exposure due to the fact that all hybrid fiber HPCC specimens show slight decreasing in flexural behavior compared to samples reinforced with 1% volume fraction of mono steel fibers after high temperature exposure.

تاريخيا يعد سلوك االنثناء للمركبات السمنتية المسلحة باأللياف الهجينة غير مفهوم بصورة متكاملة باستخدام ًالفحوصات التقليدية. بينت هذه الدراسة نتائج مختبرية اجريت على مركبات سمنتية عالية االداء احتوت على الياف حديدية مع الياف البولي بروبيلين قبل وبعد التعرض لدرجات الحرارة العالية. طور البرنامج العملي من اجل دراسة اداء االنثناء )مقاومة االنثناء والصالبة والصالدة( تحت تاثير درجات الحرارة العالية باستخدام الياف الحديد االحادية والياف الحديد-البولي بروبيلين الهجينة. قسمت الخلطات الى ثمان مجاميع مختلفة بنسبة ماء الى سمنت 0.28 على نتائج هذه الد ارسة فان من الضروري استبدالًومحتوى الياف متغير بناءاجزء من الياف الحديد المستخدمة في االلواح السمنتية المركبة بـ 15% من الياف البولي بروبيلين عند التعرض لدرجات الحرارة العالية. بصورة عامة، بالمقارنة مع نماذج احادية التسليح بـ 1% من الياف الحديد في خواص االنثناء بعد التعرض الى درجاتًاظهرت جميع االلواح السمنتية المسلحة بااللياف الهجينة تحسناالحرارة العالية.

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