Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822 Structural Behavior Of Self-Compacting Concrete Reinforced T-Beams Prof. Dr. Mohammed M. Salman Asst. Prof. Dr. Mohammed M. Rasheed Yahya S. Khudhair AL-Mustansiriya University AL-Mustansiriya University AL-Mustansiriya University College of engineering College of engineering College of engineering Civil Engineering Dept. Civil Engineering Dept. Civil Engineering Dept. [email protected][email protected][email protected]Abstract The study is concerned with the structural behavior of (12) reinforced T-shaped cross- section beams made of self-compacting concrete under flexural with two types of fibers (polypropylene and steel fibers). Compression and tensile strengths, deflection, ductility and cracking behavior are considered. Experimental results are compared with these evaluated based on the (ACI 318 – 08). The variables studied are reinforcing ratio (%ρ) (between %4.4907 - %6.0434) using different sizes of reinforcing steel bars (Ф25mm, Ф20mm, Ф16mm, Ф12mm, Ф6mm, Ф4mm, and Ф6mm wire mesh), in addition to two fibers, [polypropylene (RHEO- FIBERS ® ) and steel fibers (FIBERFORCE ® ) at a rate of [(1kg/m 3 ) & (0.5%)], respectively. The tested T-Beams were categorized into three groups, each group includes (4) T-Beams of different steel ratios (ρ %). In Group (G1), polypropylene fibers were used. In Group (G2), steel fibers were used. The reference group (G3) is with the same reinforcement ratios as in the previous two groups. It was concluded that using polypropylene fibers (RHEO-FIBERS ® )in addition to (1kg/m 3 ) in self-compacting concrete (SCC) improves the cracking control, ductility by (Δμ d = 0.5846 – 4.0514). However, fibers have minor effect on the deflection behavior of T-Beams. On the other hand, when steel fibers type (FIBERFORCE ® steel fibers) of a volume rate of (V f = 0.5% of concrete volume V c ) are used in combination with self-compacting concrete, affects the flexural behavior of T-Beams (reducing deflection, increasing ultimate loads' by (11.02% - 16.80%) and improving the ductility by (Δμ d = 4.9232 – 12.1238), but it has a minor effect on reducing the crack width. Keywords: Self-Compacting Concrete; T-Beam; Steel Fibers; Polypropylene Fibers; Superplasticizer; Silica fume; Limestone Powder; Flexural Behavior; Cracking Behavior; Deflection; Ductility Factor. 284
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
Structural Behavior Of Self-Compacting Concrete Reinforced
T-Beams
Prof. Dr. Mohammed M. Salman Asst. Prof. Dr. Mohammed M. Rasheed Yahya S. Khudhair
AL-Mustansiriya University AL-Mustansiriya University AL-Mustansiriya University
College of engineering College of engineering College of engineering
Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
(T)السلوك اإلنشائي للعتبات الخرسانية الذاتية الرص ذات المقاطع بشكل حرف
يحيى صابر خضير محمد محمد رشيد .محمد مصلح سلمان االستاذ المساعد د.االستاذ د ة المستنصريةعالجام ة المستنصرية ع الجام ة المستنصرية عالجام
لية الھندسة كلية الھندسة ك كلية الھندسة قسم الھندسة المدنية نية قسم الھندسة المد قسم الھندسة المدنية
:الخالصة ) عتب١٢( بعدد (T)أن ھذا البحث يھدف ألى دراسة السلوك األنشائي للعتبات الخرسانية ذات المقاطع بشكل حرف
مج عملي شامل ، مع األخذ وأن دراسة ھذا البحث تتضمن برنا, ) ألياف البوليمر وألياف الحديد(والمسلحة بنوعين من األلياف على سلوك الخرسانة الذاتية الرص ) ألياف البوليبروبيلين وألياف الحديد(بنظر األعتبار تأثير أضافة ھذين النوعين من األلياف
وتحسين المطيلية ، باألضافة ألى نمط وعرض , ومقدار الھطول , ومقاومة الشد , مقاومة األنضغاط (كتأثيرھا مثال على ومقارنة النتائج المستحصلة عمليا مع النتائج المحسوبة تخمينيا ) الذي ممكن أن يظھر في الخرسانة الذاتية الرصالتشقق
المتغيرات التي تم . وكل ھذا تم دراسته خالل ھذا البحث العملي , )٢٠٠٨( لسنة (ACI 318طبقا للمدونة األمريكية المرقمة وذلك %) ٦.٠٤٣٤ - % ٤.٤٩٠٧( حيث تم أخذھا بنسب تتراوح مابين (%ρ)دراستھا خالل البحث ھي نسبة التسليح
٦شبكة بقطر , ملم ٤, ملم ٦, ملم ١٢, ملم ١٦, ملم ٢٠, ملم ٢٥(بأستخدام أقطار مختلفة من قضبان حديد التسليح ھي / كغم ١(ضافة مقداره بمعدل أ) ®RHEO-FIBER(باألضافة ألى ذلك أنه تم أستخدام ألياف البوليبروبيلين من نوع , ) ملمكنسبة حجمية من الحجم الكلي للخرسانة ) ٠.٥%( بنسبة أضافة مقدارھا (®FIBERFORCE)وألياف الحديد من نوع , ) ٣م
كل مجموعة أستخدم فيھا أربع نسب , تم توزيعھا على ثالث مجاميع (T)كل العتبات ذات المقاطع بشكل حرف . الذاتية الرص وھذه النسب تم تكرارھا على المجاميع الثالثة مع أستخدام ألياف البوليبروبيلين , لفة من حديد التسليح من التسليح بأقطار مخت
بينما تم أستخدام ألياف الحديد , في خلطة الخرسانة الذاتية الرص لعتبات المجموعة األولى (®RHEO-FIBERS)من نوعأما المجموعة الثالثة فقد تم , لعتبات المجموعة الثانية في خلطة الخرسانة الذاتية الرص (®FIBERFORCE)من النوع
. صبھا بدون أستخدام أي نوع من األلياف لكونھا المجموعة التي سوف يتم المقارنة معھا / كغم ١(وقد أظھرت النتائج العملية لھذا البحث أنه بأضافة ألياف البوليبروبيلين من النوع أعاله وبنسبة أضافة مقدارھا
مع الخرسانة الذاتية الرص تؤثر بدرجة كبيرة على تحسين السيطرة على التشققات التي يمكن أن تحصل للخرسانة وتعمل ) ٣م، بينما ]٤.٣٥١٥ ألى ٢.٠٣٥٦) = Δμd(التغير بالمطيلية [وكذلك تحسين عامل المطيلية بمقدار يتراوح مابين , على تقليلھا
لكن عندما يتم أستخدام ألياف الحديد من النوع . ول للعتبات الخرسنية الذاتية الرص قليال يكون تأثيرھا على تقليل مقادير الھط(FIBERFORCE®) تظھر تأثيرا كبيرا ) من الحجم الكلي للخرسانة الذاتية الرص%0.5( وبنسبة أضافة حجمية مقدارھا
ألى % ١١.٧٨(ي بمقادير عالية تتراوح مابين على تقليل مقادير الھطول وزيادة مقدار الحمل األقصى لفشل العتب الخرسانولكنھا , ]١٢.١٢٣٨ ألى ٤.٩٢٣٢) = Δμd(التغر بالمطيلية [مع تحسين عامل المطيلية بمقدار يتراوح مابين %) ١٨.٤٢
تكون ذات تأثير قليل على تقليل عرض التشققات التي تظھر على العتبات الخرسانية الذاتية الرص ذات المقاطع بشكل حرف (T).
؛ الملدنات المتفوقة؛ )البوليبروبيلين(؛ ألياف البوليمر د؛ ألياف الحدي(T)الخرسانة الذاتية الرص؛ العتب ذو المقطع بشكل :دالةالكلمات ال؛ مسحوق حجر النورة الكلسي؛ السلوك المرن؛ سلوك التشقق؛ الھطول؛ )مادة بوزوالنية ذات خواص أسمنتية(مسحوق السيليكا الفعال
. مل المطيليةعا
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
1. General Self-compacting concrete (SCC) represents one of the most significant advances in concrete
technology. Inadequate homogeneity of the cast concrete due to poor compaction or segregation
may drastically lower the performance of nature concrete at site. (SCC) has been developed to
ensure adequate compaction and to facilitate placement of concrete in structures with congested
reinforcement and in restricted areas(1).
2. Scope & Objectives Experimental work includes a comparison between three groups of twelve T-Beams, each
group contains four T-Beams having the same Self-Compacting Concrete mix of the same strength
in the same group, but with different reinforcement ratios for the four beams in each group.
Polymeric or polypropylene fibers of (1kg/m3) ratio and steel fiber of (Vf= %0.5) were used in the
first and second groups respectively, while the third group was without reinforcing fibers.
Comparison is made between flexural behavior and cracking behavior of the elements in each
group.
3. Details of Test Beams The used dimensions of test beams are (1500mm) in overall length and (250mm) in total depth,
the effective width of flange is (330mm), the thickness of flange is (40mm), the clear width of web
is (180mm) and the web depth is (210mm) as illustrated in Figure (1).
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
Stirrup Ф12mm@40mm (c/c).
The whole beams are made of the same type of concrete, with no cold joints between its web and
flange, the type of loading during the test of T-beam samples is of two-point loading as illustrated
in Figure (2). So, the third clear span of loading is (430mm) and the distance from the face of beam
edge to the center of supports is (105mm), there is the same distance to the two beam sides. The
type of beam supporting is simply supported. Plate (1) shows the T-Beam setup for testing stage
with three dial gauges under its web.
210
430m430m
(c) Details of Shear Reinforcement (Stirrup)
Figure (1): Details of Flexural T-Beam.
.T-Beam Cross-section) b(
(a) Details of distributed Stirrup Bars along T-Beam shear span length with
concrete covers.
250mm
105 105
1500 mm
Cc = 20mm Cc =
20mm
20
10mm
)mm20 = (Cc Cc= (20mm)
Bent up
70 140mm
220m
m
330mm
180 mm
20mm (Cc)
4٠m
m
250m
m
20 20
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288
Plate (1): The T-Beam set up with Three Dial Gauges.
Point Load Point Load
330 mm
Flange
40m
m 40m
m
250 mm
250m
m
Web
180 mm
430mm 430 mm 430 mm 105mm 105 mm
1500 mm
Fig e. ure (2): Application of Two-point Loading upon T-Beam flang
Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
4. Materials Materials were selected according to a mix design method taking into account material grading
& properties. Satisfactory SCC is achieved by more strength requirements of the ingredients in
selecting suitable materials, and good quality control and proportioning.
4.1. Cement MASS BAZIAN SULAIMANIA Portland cement type (1) was used. It was tested according to
the Iraqi Standard Specifications (IQS) No. 5/1984(2) for the physical and chemical properties, as
shown in Tables (1) and (2), respectively.
Table (1): Physical Properties (Composition) of Cement
Physical Properties Test
Results
Iraqi Specifications
No.5/1984
Fineness using Blain air permeability apparatus(m2/kg) 381 > 230
Initial setting time using Vicat's instruments (hr:min.) 1:55 > 00:45
Final setting time using Vicat's instruments (hr:min.) 4:25 < 10:00
Safety (soundness) using autoclave method (%) 0.01 < 0.8
Compressive strength for cement paste cube (70.7mm) at :
(3days) in (N/mm2) or (MPa) 25.85 > 15
Compressive strength for cement paste cube (70.7mm) at :
(7days) in (N/mm2) or (MPa) 28.0 > 23
4.2. Fine Aggregate Al-Ukhaidher natural sand with fineness modulus of (2.69) was used it is of rounded particle
shape and smooth textures and of a maximum size of (4.75mm),therefore, requires less mixing
water in concrete and for this reason it is preferable in SCC. Grading and sulfate content are shown
in Table (3).Which satisfy the Iraqi Standard Specifications No.45 / 1984(3)– Zone No. (2).
4.3. Coarse Aggregate Crushed gravel of maximum size of (19mm) was used from Al-Niba'ee quarry region. Table
(4) shows the grading and percentage of sulfate content of the aggregate, which confirms to the
Iraqi Standard Specification No.45 / 1984(3) – size of grading (5-20) mm.
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
Table (2): Chemical Composition of Cement
Numbering Compound
Name
Compound
Chemical
Composition
% (weight)
Iraqi Standard
Specifications
No.5/1984
1 Silica SiO2 19.80 -------
2 Alumina Al2O3 5.11 -------
3 Iron Oxide Fe2O3 3.28 -------
4 Lime CaO 64.53 -------
5 Magnesia MgO 1.78 < 5
6 Sulfate SO3 2.55 < 2.8
7 Insoluble
Residue I.R. 1.06 < 1.5
8 Loss on ignition L.O.I 3.11 < 4
8.29 (From X.Ray
diffraction) 9
Tricalcium
aluminates C3A
7.9983 (From Bogue
equations)
-------
10 Lime saturation
factor L.S.F 0.98 0.66-1.02
11 C4AF 9.9712 ----------
12 Tricalcium
silicate C3S 65.86 ----------
Dicalcium
silicate C2S 7.16756 ---------- 13
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Table (3): The Grading and Sulfate Content of Fine Aggregate (Sand)
Sieve Size Iraqi specification No. 45/1984 for
grading Zone(2) of % passing of
fine aggregate
Deviation
% Cumulative of
passing fine
aggregate In
(μm)
In
(mm)
No.
100 0 100 10000 10 1
90-100 0 94 4750 4.75 2
75-100 0 82 2360 2.36 3
55-90 0 69 1180 1.18 4
35-59 0 55 600 0.6 5
8-30 0 24 300 0.3 6
0-10 0 7 150 0.15 7
<5 ----- 4.1 75 0.075 8
------ ----- 0 Pan 9
< 5 0 Summation of deviations 10
< 0.5 % Sulfates Content = 0.069 11
Table (4): The Grading and Sulfate Content of Coarse Aggregate (Gravel).
Sieve Size Limit of Iraqi specification No.
45/1984 for grading size (5-20)mm of
% passing of coarse aggregate
Deviation
% Cumulative of
passing fine
aggregate In
(μm)
In
(mm)
No.
75000 75 1
100 0 100 37500 37.5 2
95-100 0 99 20000 20 3
14000 14 4
30-60 0 30 10000 10 5
0-10 0 3 5000 5 6
2360 2.36 7
< 3.0 ----- 0.0 75 0.075 8
------- ----- 0 Pan 9
0 0.00 Summation of deviations 10
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< 0.1 % Sulfates Content = 0.05 11
4.4. Limestone Powder Limestone powder has been used as filler for concrete production for many years. It has been
found to increase workability and early strength, as well as to reduce the required compaction
energy. The increased strength is found particularly when the powder is finer than the Portland
cement particles. The fine limestone powder (locally named as Al-Gubra) of Iraqi northern zone
with fineness (411 m2/kg) is used to avoid excessive heat generation, enhance fluidity and
cohesiveness, improve segregation resistance and increase the amount of fine powder in the mix
(cement and filler). According to EFNARC(٤), the fraction less than 0.125 mm was of most
benefit. Typical properties of lime stone powder (L.S.P) are listed in Table (5).
Table (5): The Typical Properties of Limestone Powder (L.S.P)
Physical property Range
Fineness by using Blain apparatus (m2/kg) 411
Chemical Composition % Content
So3 1.63
CaCo3 94.90
4.5. Mixing Water Ordinary tap water was used for both mixing and curing.
4.6. Superplasticizer The superplasticizer or High Range Water Reducing Admixture (HRWRA), used in this type of
concrete, is one of the high performance concrete superplasticizer based on modified
polycarboxylic ether. GLENIUM 51(5)is the superplasticizer which was used, it is free from
chlorides and complies with ASTM C494 Type A and F.
GLENIUM 51 is compatible with all Portland cements that meet recognized international
standards. It is differentiated from conventional superplasticizers in that it is based on a unique
carboxylic ether polymer with long lateral chains. This greatly improves cement dispersion.
GLENIUM 51 is available in 208 liter drums and in bulk tanks upon request. Table (6) illustrates
some important typical properties of GLENIUM 51 according to the requirements of BASF Middle
East Technical Products Guide. The normal dosage of GLENIUM 51 is between 0.5 and 1.6 liters
per 100 kg of cement (cementitious material). Dosages outside this range are permissible subject to
trial mixes. The maximum effect is achieved when the GLENIUM 51 is added after the addition of
50 to 70 % of the water. GLENIUM 51 must not be added to the dry materials, through mixing is
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
essential, and a minimum mixing cycle after the addition of the GLENIUM 51, of 60 seconds for
forced action mixers is recommended.
Table (6): Typical Properties of GLENIUM 51(5).
Form Viscous Liquid
Colour Light Brown
Relative Density 1.08 – 1.15 @ 25°C
pH 6.6
Viscosity 128 +/- 30 cps @ 20°C
Transport Not classified as dangerous
Labeling No hazard label required
4.7. Reinforcing Steel All the reinforcing steel bars, used in this study, are deformed and of Ukrainian origin with a
nominal diameter (Ф) of (4,6,12,16,20, 25 and B.R.C Ф 6) mm.
Table (7): Test Results of Reinforcement Steel Bars
Bars Diameters
(mm)
Yield stress
(ƒy),(MPa)
Ultimate stress
(ƒt),(MPa)
Estimated Modulus
of Elasticity
(Es),(MPa)×103
4 445 670 200
6 460 662 200
B.R.C Φ6 529.25 960.95 200
12 476.13 680.86 200
16 489.57 734.36 200
20 505.17 727.44 200
25 486.36 719.81 200
4.8. Steel Fibers (SF) FIBERFORCE® is cold drawn wire steel fiber meeting the ASTM A820-96 Type 1
requirements as well as C1116 section 4.1.1 requirements.
4.9. Polymer or Polypropylene Fibers (P.F.)(5)
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Journal of Engineering and Development, Vol. 17, No.1, Mar. 2013, ISSN 1813‐ 7822
Table (8) illustrate the typical properties of polypropylene fibers (RHEOFIBER®) which are used
in this experimental study.
Table (8): Typical Properties of RHEOFIBER®(5)
Specific gravity 0.91 g/cm3
Alkali content Nil
Sulphate content Nil
Area entrainment Area content of concrete will not be significantly increased
Chloride content Nil
Constituents Polymerized polypropylene
Fiber diameter 18 micron
Fiber length 12 mm
Surface area 230 m2/kg min.
Young’s modulus 3500-3900 MPa
Tensile strength Min 350 MPa
Melting point 160°C
4.10. Pozzolanic Additives (micro-silica)(5)
Table (9): Typical Properties of MEYCO® MS610 (5)
Form Powder
Colour Grey
Bulk density 550-700 kg/m3
Chloride content < 0.1%
5. Results of Fresh SCC Tests According to the fresh tests of the four self-compacting concrete mixes, the results are shown
in Table (10).
6. General Behavior of Tested T-Beams Test results that describe behavior of tested T-Beams are shown in Tables (11-13) as hereafter.
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