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Article
Residual Mechanical Properties of Self-Compacting Concrete Exposed to Elevated Temperatures

Author: Manolia Abed Al-wahab Ali
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 7 Pages: 1386-1390
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This study aims to investigate the residual mechanical properties (compressivestrength, modulus of rupture and dynamic modulus of elasticity) of selfcompactingconcrete (SCC) exposed to elevated temperatures ranging from (100-800 oC) as well as studying its fresh and hardened properties at normaltemperature. Also it aims to study the influence of high reactivity metakaoline(HRM), as a partial replacement by weight of cement, for improving its mechanicalproperties after and before exposure to elevated temperatures.The concrete specimens were subjected to a temperature range of (100,200, 400, 600 and 800oC) with an exposure duration of 2-houres. The test resultsshowed that the performance of SCC containing HRM is higher than that of SCCwithout HRM , where the residual compressive strength of HRM SCC after anexposure to a temperature level of (800oC) was 73.2% while for the normal SCCwas 65% from their original strength .At the same exposure temperature (800oC) ,the loss in modulus of rupture is higher than that of compressive strength , thedifference was between (2% - 12.4%). Also the reduction in dynamic modulus ofelasticity (Ed) is higher than that of compressive strength and modulus of rupture,where the residual (Ed) was between (47.3% - 63.5%) after 800oC exposure.

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Article
The Possibility of Produce Self Compacted Polystyrene Concrete
إمكانية إنتاج خرسانة البوليستايرين الذاتية الرص

Author: Manolia Abed Al-wahab Ali منوليا عبد الوهاب علي
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2012 Volume: 16 Issue: 4 Pages: 127-141
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The aim of this study is to produce one types of self-compacted lightweight concrete which is known as self-compacted polystyrene concrete (SC-PC) . The SC-PC was produced by using expanded polystyrene beads as a partial replacement by volume of sand,(Glenium 51) as a superplastisizer and styrene butadiene rubber (SBR) as a viscosity modifying agent to prevent the segregation of beads .Also studying the fresh and hardened properties of (SC-PC) (density, compressive, strength, flexural strength and tensile strength). The results indicated that it is possible to use polystyrene beads for producing (SC-PC) with density ranging from (1660-1895)kg/m3 and a 28-days compressive strength ranging from (10.23 – 14.65) MPa .The results also showed that the properties of (SC-PC) are mainly influenced by the content of polystyrene beads and decrease with the increase of polystyrene content . The density of (SC-PC) decreases to (12.4%) when the percentage of sand replacement with polystyrene beads increased from (16.7% to 50%) .While the compressive , tensile and flexural strength decrease to (30.17, 37.93 and 43.3%) respectively when the polystyrene content increased from (16.7% to 50%) by volume of sand .

تهدف هذه الدراسة إلى إنتاج احد أنواع الخرسانة الخفيفة الذاتية الرص والتي هي خرسانة البوليستايرين الذاتية الرص ، تم إنتاج هذه الخرسانة باستخدام حبيبات البوليستايرين المتمددة كاستبدال جزئي من حجم الرمل مع (Glenium 51) كملدن متفوق و(styrene butadiene rubber) (ٍSBR) كعامل مساعد للزوجة لمنع انعزال حبيبات البوليستايرين . كما تم دراسة الخواص الطرية والصلبة لخرسانة البوليستايرين الذاتية الرص و هي (الكثافة ومقاومة الانضغاط والشد والانثناء) .لقد دلت النتائج على إمكانية استخدام حبيبات البوليستايرين في إنتاج خرسانة البوليستايرين ذاتية الرص بكثافة تتراوح بين (1660 – 1895)كغم/م3 ومقاومة انضغاط بعمر 28 يوم بين (10,32 – 14,65) ميكا باسكال . كما أشارت النتائج إلى أن خواص (SC-PC) تتأثر بشكل كبير بمحتوى البوليستايرين حيث تقل بزيادة محتوى البولستايرن. كثافة (SC-PC) تقل بمقدار (12,4%) عندما تزداد نسبة استبدال الرمل بالبولستايرين من (16.7% - 50%) . بينما مقاومة الانضغاط والشد والانثناء تقل لحد (30,17% و 37,93% و 43,3%) على التوالي عندما محتوى البوليستايرين يزداد من (16,7% - 50%) من حجم الرمل .

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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
Empirical Formulas For Estimation Of Some Physical Properties Of Gas Concrete Produced By Adding Aluminum Powder
معادلات تجريبية لتخمين خواص الخرسانة الغازية المنتجة باضافة مسحوق الالمنيوم

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Abstract

The aim of this study is to produce one types of lightweight concrete which is known as ( gas concrete ) , four additions of aluminum powder ( 0.1, 0.2, 0.3, 0.4) % by weight of cement were used to produce gas concrete. Two different ways for curing, air and steam curing, were carried out using (5) cm cubes specimens.The test results showed that the density and compressive strength of gas concrete decreases with the increase of percentage of aluminum powder (AL).The density of gas concrete was between (1177.1-1524.38) kg/m3and (1246.24-1593.94) kg/m3 for air and steam curing, respectively when the percentage of aluminum powder was between (0.1—0.4) % by weight of concrete. The addition of (AL) also increases the volume of gas concrete. It was between (13.3- 50.8) % and (18.7 – 61.3) % for air and steam curing respectively when (Al) was between (0.1-0.4) %The test results showed that the best percentage of (Al) was 0.2% by weight of cement which gives density (1389.98) kg/m3 and compressive strength (0.26) MPa for air curing and (1431.95) kg/m3and (0.55)MPa for steam curing. Statistical analysis is done to find mathematical relationships to predict some variables of gas concrete {density, compressive strength, the percentage of expansion and percentage of (Al)} for both air and steam curing concrete .

تهدف هذه الدراسة إلى إنتاج احد أنواع الخرسانة الخفيفة الوزن والتي تعرف بالخرسانة الغازية ( المهواة ) . تم استخدام أربع نسب إضافة من مسحوق الألمنيوم ( 0.1 ،0.2 ،0.3 ،0.4) كنسبة مئوية من وزن السمنت لإنتاج الخرسانة الغازية. تم استخدام طريقتين لمعالجة النماذج الخرسانية وهي طريقة المعالجة العادية بالهواء والمعالجة بالبخار مع استخدام نماذج مكعبة بأبعاد (5) سم . أظهرت نتائج الفحوصات إن الكثافة ومقاومة الانضغاط للخرسانة الغازية تقل مع زيادة نسبة مسحوق الألمنيوم (Al) .حيث كانت كثافة الخرسانة الغازية بين(1177.1-1524.38) كغم/ م 3وبين(1246.24-1593.94)كغم /م 3 لطريقتي المعالجة العادية والمعالجة بالبخار على التوالي . عندما كانت نسبة مسحوق الألمنيوم بين(0.1 -0.4)% من وزن السمنت . إن إضافة مسحوق الألمنيوم أيضا تزيد من حجم الخرسانة الغازية حيث كانت الزيادة بالحجم بين ( 50.8 – 13.3 )% و(61.3 – 18.7 )%للخرسانة المهواة المعالجة العادية بالهواء والمعالجة بالبخار على التوالي عندما كانت نسبة مسحوق الألمنيوم بين ( 0.1-0.4)% من وزن السمنت.أظهرت نتائج الفحوصات إن أفضل نسبة لمسحوق الألمنيوم كان0.2 % من وزن السمنت والذي أعطانا كثافة(1389.98 ) كغم/م ومقاومة انضغاط(0.26)ميكاباسكال بالنسبة للمعالجة العادية بالهواء و(1431.95 )كغم/م و(0.55 )ميكاباسكال للمعالجة بالبخار.

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