Evaluation some properties of high performance concrete reinforced with steel fiber

مقدم أطروحة جامعية

Tahir, Muntazar Jabbar

مشرف أطروحة جامعية

Hasan, Man Salman
al-Azzawi, Ziyad M.

الجامعة

الجامعة التكنولوجية

الكلية

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القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

Concrete may be regarded as high performance concrete (HPC) for several different reasons: high strength, high workability, high durability, and perhaps improved visual appearance.

According to American Concrete Institute ACI, HPC is defined as a concrete meeting special combination of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practices.

The aim of this research is to evaluate the performance of high performance concretes (HPC) containing steel fiber, silica fume, and superplasticizer under the effect of standard and heat curing.

This study presents an experimental and analytical evaluation of mechanical properties, durability, and microstructure properties.

The variables studied were: mixture proportions, age, and curing treatment methods.

Four volume fractions of steel fiber with aspect ratio (fiber length/ fiber diameter) of 60 were used, 0, 0.5, 1.0, and 2.0 %.

Incorporations of silica fume into the concrete were 0% and 15% as a cement replacement by weight.

Two methods of curing were applied: 1) normal curing conditions, following the standard curing procedure, and 2) heat curing conditions, heat curing at 80 ˚C for five days in temperature controlled box, then at 100 ˚C in drying-oven for one day.

Concrete were prepared to have a slump around 170 mm at different water/binder ratios.

An experimental investigation was carried out to specify and investigate some mechanical, durability and microstructure properties of High Performance Concrete.

These properties include compressive strength, splitting tensile strength, flexural strength, direct tensile strength, static modulus of elasticity, rapid chloride penetration, electrical resistivity, X-ray diffraction, and fracture surface observations using scanning electron microscope.

Total number of (526) specimens were cast, cured either under normal or heat curing methods, and tested at different ages, following standard testing procedures.

Mechanical properties results of this study showed that the use of silica fume increase both all strengths and the modulus of elasticity of concrete.

The enhancement rate however is more pronounced in later age for normal curing conditions and in early age in accelerated curing conditions.

On the other hand, the addition of steel fiber into the high performance concrete improves tensile strengths significantly reached up to 115%.

The degree of improvement is related to the percentages of steel fiber used.

Volume fraction 2% seems to be the optimum value based on the flexural and tensile behavior.

Similar behavior is observed from the modulus of elasticity test results.

Rapid chloride penetration test and electrical resistivity results revel that specimens incorporating silica fume have higher resistance to chloride penetration and electrical conductivity.

In contrast, steel fibers content have adverse effect on the concrete electrical and chloride penetrations resistivity, regardless the curing method used.

X-ray diffraction analyses indicated that the application of heat curing combined with using silica fume caused a significant decrease (consume) in Ca(OH)2 content and increase in content of quartz, leading to enhance the fiber matrix interface and density the structure of the matrix.

Fracture surface observation generally confirmed the results of X-ray diffraction.

SEM images revel reduction in cracks number and width in specimens containing silica fume.

Fibers rupture as well as fibers pullout are also observed.

This study demonstrates the beneficial combined effect of silica fume, steel fiber, and heat curing on the strength and durability of high performance concrete.

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

الموضوعات

• مواد البناء
• الخرسانة
• الخرسانة المسلحة

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-420202