research centers


Search results: Found 3

Listing 1 - 3 of 3
Sort by

Article
IMPROVING MECHANICAL PROPERTIES OF LIGHTWEIGHT FOAMED CONCRETE USING SILICA FUME AND FIBERS

Authors: Suhad Mohammed Abd --- Dhamyaa Ghalib Jassam
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 2 Pages: 184-199
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

Lightweight foamed concrete (LWFC) is characterized as a light in self-weight, self-compacting (no need vibration), self-leveling, and thermal and sound isolation. The application of (LWFC) in the building construction is limited because of its the low strength and the low ductility. In this study the workability of the fresh mix of (LWFC), the hardened properties include, compressive strength, tensile splitting strength, flexural strength, and modulus of elasticity were evaluated. This study focuses mainly on the effect of the adding of silica fume and fibers on the mechanical properties of (LWFC). Silica fume was added as 5% and 10% by the weight of cement. Steel fiber and polypropylene fiber volume fraction were of (0.2%, 0.4%), While the hybrid fibers (steel+ polypropylene) volume fraction was (0.2% steel+0.2%PP), and (0.4%steel+0.2%PP) of the total mix volume. The results of the program test show that the increase of silica fume improves the mechanical properties of (LWFC) significantly. The adding of fibers to the (LWFC) reduces the flowability and improves the mechanical properties. The hybrid fibers mix (0.4% steel+0.2% PP) presented the best test result of the mechanical properties as (10%,21%,53%, 24.4%) for the compressive strength, flexural strength, tensile splitting strength, and modulus of elasticity, respectively.


Article
EFFECT OF DIFFERENT TYPES OF LIGHTWEIGHT AGGREGATE ON STRENGTH AND MODULUS OF ELASTICITY OF CELLULAR CONCRETE

Authors: Suhad Mohammed Abd --- Dunay Khalil Ismail
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 5 Pages: 193-206
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

The objective of this study is to improve properties of structural foamed concretes by adding fine and coarse lightweight aggregate. The materials that used in this study were fly ash as fine material and various type of lightweight aggregate (Leca, porcelanite). The mechanical properties included fresh and hardened density, compressive strength and elasticity modulus were tested in this study. The results show increases in compressive strength and modulus of elasticity by increasing the percentage of fine aggregate (fly ash).The optimum percent is 50% for fine aggregate (fly ash).The compressive strength decreases with increasing the percentage of lightweight coarse aggregate .The modules of elasticity increases by increasing the replacement percentage of fly ash . The addition of lightweight coarse and fine aggregate affect on the percentage of foam need be added to the mix for the desired density. Type of aggregate have significant effect on compressive strength and modulus of elasticity for foamed concrete. Flyash increase in compressive strength about (39%). Light weight aggregate decrease in compressive strength about (2-50) %. Flyash increase in modulus of elasticity about (10-56)% and light weight aggregate increase in modulus of elasticity about (1-20)%. Fly ash and lightweight aggregate (Leca and Porcelanite) improved the properties of foamed concrete.


Article
BEHAVIOUR AND STRENGTH OF SUSTAINABLE RUBBERIZED REINFORCED CONCRETE BEAMS STRENGTHENED BY CFRP
تصرف ومقاومة العتبات الخرسانية المسلحة والمستدامة المصنوعة باستخدام مخلفات المطاط والمقواة بألياف الكاربون البولمرية

Authors: Suhad Mohammed Abd --- Ahmed Abdullah Mansor --- Amer Mohamed Ibrahim
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2016 Volume: 20 Issue: 6 Pages: 156-170
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

The current study is interested for investigating the effect of replacing 50% of sand by textured rubber (Crumb Rubber) that reduced 10% from specimen's weight, then using the CFRP to strengthening the flexural efficiency of beams. Five specimens with 200x300x2000mm dimensions are investigated. The variables are studied in instillation of CFRP. Three situation of fixing the CFRP, the first is in area exposed to flatten, the second in both regions of tension and compression and the last one covered all faces by CFRP. Laboratory results showed that when replacing 50% of sand by crumb rubber the weight of beams decreased by 9% and increased the ductility by 74% also the crack width is reduced by 9% and 38% at yield and ultimate loads respectively. Strengthening by CFRP strips is increase the yield and ultimate load by 40% and 35% on average respectively, but by covering all faces the ratios was increased by 60% and 63%. Using the crumb rubber decreased the deflection by 27% on average and by using CFRP the defection was decreased by 36%, 19% on average at yield and ultimate load respectively. CFRP is increase the strain in compression face of concrete and the value was greater than maximum strain of concrete (0.003). Also the crack width was decreased by 45% , 23% on average at yield and ultimate loads respectively.

اهتمت الدراسة الحالية في تحري تأثير استبدال 50% من الرمل بمادة مخلفات المطاط الذي ساهم بتقليل 10% من وزن النماذج وكذلك استعمال الياف الكاربون لتقوية كفاءة الانثناء في العتبات. اشتملت الدراسة على صب خمسة نماذج بابعاد 200x300x2000 ملم. تم دراسة تاثير تثبيت صفائح الكاربون. هناك ثلاث حالات لتثبيت صفائح الكاربون، الاولى في المنطقة المعرضة للشد والثانية في المناطق المعرضة للشد والانضغاط والثالثة بتغليف النموذج بالكامل. النتائج المختبرية أظهرت ان استبدال 50% من الرمل بمادة مخلفات المطاط قلل وزن العتبات بنسبة 9% وزاد من المطيلية بنسبة 74% اضافة الى تقليل عرض التشقق بمقدار 9% و38% من حملي الخضوع والفشل على التوالي. وعند تعزيز النماذج باشرطة الياف الكاربون يزداد حمل الخضوع والفشل بمعدل 40%و 35% على التوالي، اما في حالة بتغطية كامل النموذج فتكون الزيادة بنسبة 60% و63% على التوالي. ان استخدام مخلفات المطاط ، يقلل الهطول بمعدل 27% في مرحلة الخضوع ، وباستخدام الياف الكاربون يقل الهطول بنسبة 36% و19% عند حملي الخضوع والفشل على التوالي. ان استخام الياف الكاربون يزيد من انفعال الخرسانة الى قيم تتجاوز اعلى قيمة لانفعال الخرسانة (0.003). بالاضافة الى تقليل عرض التشققات بمعدل 45% و23% عند حملى الخضوع والفشل على التوالي.

Listing 1 - 3 of 3
Sort by
Narrow your search

Resource type

article (3)


Language

English (3)


Year
From To Submit

2019 (2)

2016 (1)