Document Details

Document Type : Thesis 
Document Title :
EFFECT OF CORE SIZE AND ORIENTATION ON ASSESMENT OF HIGH STRENGTH SELF COMPACTED CONCRETE
تأثير حجم وإتجاه القلب الخرساني على تقييم الخرسانة ذاتية الدمك عالية المقاومة
 
Subject : Faculty of Engineering 
Document Language : Arabic 
Abstract : The core test is a primary and reliable technique for assessing compressive strength of existing concrete structures. The compressive strength of concrete cores is affected by many parameters; one of these is the strength of the concrete itself. This is achieved by using correction factors from standards such as ASTM C 42/C 42M-04, but this standard is intended for normal strength concrete (NSC) and give limited information for high strength concrete (HSC). Literature contains very limited studies related to the HSC core compressive strength, i.e, there is no study at all for above 100 MPa strength. Generally, compressive strength test is conducted with the core size of 100 mm x 200 mm, but it is difficult to extract core sample of 100 mmx 200 mm from concrete structures where steel reinforcements are closely packed in concrete in concrete or thickness of member has less than 200 mm depth. Inaddition, coring will weaken the structural because of the big core sizes and then the numbers of core samples have to be limited to prevent the reductions in the structure sections. In this study, a slab (3 x 1.5 x 0.2) m3 and a beam (4 x 1.0 x 0.2) m3 were cast to obtain core samples. The target strength for the beam was 115 MPa, while it was 130 MPa for the slab. Four core diameters of 25, 50, 75 and 100 mm were extracted and for each core diameter four slenderness ratios (λ=l/d) of 2, 1.75, 1.5 and 1.0 were used for assessment of strength parallel and perpendicular to the casting direction. The relationship between the strength of concrete with respect to reference samples and different core sizes with different slenderness ratio, λ, was investigated. Ultrasonic Pulse Velocity (UPV) test was conducted for all samples and the relationship between UPV and strength of cores was determined. The results of the study were compared with the correction factors of the current ASTM C 42/C 42M-04 and indicated that the correction factors listed in the standard cannot cover HSC. This difference necessitates modification of equations and correction factors that are used to determine the compressive strength of concrete in structures. The results showed that the correction factors for the strength of standard cylinder of HSC is different from normal strength concrete (NSC) and have ranged from 0.95 to 1.26. It was also found that the vertically cored samples (parallel to casting direction) were slightly stronger than horizontally cored samples (perpendicular to casting direction) and the difference increase as the strength of concrete increased. Relationships between core compressive strength and UPV values were also established. 
Supervisor : Prof. Ramazan Demirboga 
Thesis Type : Master Thesis 
Publishing Year : 1438 AH
2017 AD 
Co-Supervisor : Dr. Waleed H. Khushefati 
Added Date : Tuesday, July 11, 2017 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
طراد محمد الزهرانيAl-zharani, Traad MohammedResearcherMaster 

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