Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : SCC


Experimental Behavior of Self Compacting Concrete Corbels Strengthened with External CFRP

Sarmad Sh. Abdulqader; Basil Salah Al-Shathr; Ali Kh. Hasan

Engineering and Technology Journal, 2018, Volume 36, Issue 2A, Pages 154-162
DOI: 10.30684/etj.36.2A.6

This research aims to study the influence of using Carbon Fiber Reinforced Polymer (CFRP) strips as an external strengthened and repairing material on the behavior of self-compacting concrete (SCC) Corbels. The experimental work involved testing twenty self-compacting concrete corbels specimens. The experimental work is divided into two parts; the first part consists of three groups to investigate the most effective direction, position, bonding type and amount of CFRP strips on the behavior of corbels and utilized it in practice, also to strengthen new variables that are investigated in the second part. Two groups in part one are strengthened with different numbers of inclined and horizontal direction of CFRP strips, while in the third group the specimens were strengthened with strips of CFRP having different directions and bond types to improve the strength capacity and behavior of corbels. This improvement is represented by increase cracking load by about (94)% and increase in their ultimate load capacity of strengthening corbels which varies from about (19 to 88)%. While the second part of experimental work included the following variables: shear span to effective depth ratio (a/d), amount of horizontal steel reinforcement stirrups and repaired damaged corbels. The reinforced concrete corbels in this part were strengthened and repaired by CFRP strips depending on optimum result that is produced from part one wherefrom position, direction and amount are considered. It was found for un-strengthened and strengthened corbels having same horizontal secondary reinforcement stirrups that when (a/d) ratio decreases from 0.65 to 0.4 causes increase in cracking and ultimate loads reach (55)% and (35.41)% respectively. For un-strengthened and strengthened corbels having same (a/d) ratio, it was found an increase in cracking load which varies from (6.66 to 34.78)% and from (18.18 to 52.63) % in ultimate load when horizontal secondary reinforcement stirrups are increased. It was also found repairing SCC corbels with CFRP strips causes an increase in ultimate load reaching up to (50)% with respect to un-strengthened specimens. From results it is concluded that strengthened or repaired corbels present stiffer load deflection response than corresponding un-strengthened corbel (control corbel).

Density and Ultrasonic Pulse Velocity Investigation of Self-Compacting Carbon Fiber- Reinforced Concrete

G.A. Salman

Engineering and Technology Journal, 2018, Volume 36, Issue 1A, Pages 89-99
DOI: 10.30684/etj.2018.136783

comprehensive research has been carried out to understand the effect of adding carbon fibers to density and ultrasonic pulse velocity of self-compacting concrete. Fifteen SCC mixes were prepared with two types of mineral admixtures and carbon fibers. Metakaoline and silica fume were used as mineral admixtures while carbon fibers were used as fiber inclusions. Two different fiber length (6mm and12mm) and fiber fraction (0.1 % and 0.5 %) was used. Different parameters such as slump flow diameter, T500 time, V-funnel time, blocking ratio and filling height difference were used to evaluate fresh state properties. Air-dry density and Ultrasonic Pulse Velocity values are determined for mixes at age of 7, 28, 90 and 180 days. The experimental results indicate that concrete mixes contained carbon fiber showed higher air dry density than concrete mixes without fiber, the percentage increase were between 0.85% to 3.31% at age (7,28,90 and 180) days respectively. Concrete mixes contained carbon fiber compared with the reference mixes without carbon fiber exhibits an increase in the ultrasonic pulse velocity values of about 0.74% to 5% at age (7,28,90 and 180) days respectively .

Experimental Behavior of Circular Steel Tubular Columns Filled with Self-Compacting Concrete under Concentric Load

Saad N. Sadik; Wael S. Abdul-Sahib; Ammar A. Ali

Engineering and Technology Journal, 2013, Volume 31, Issue 14, Pages 2760-2772

This paper presents an experimental study on the behavior of circular, concretefilled,
steel tube (CFT) columns concentrically loaded in compression to failure. Selfcompacting
concrete (SCC) is used here as a filler in order to increase homogeneity of
the core and reduce segregation problems. Total six column specimens with different
lengths (0.4 m – 1.5 m) of constant diameter of 160 mm and wall thickness of 2.8 mm
were tested. The purpose here is to investigate the ultimate capacity and the
deformation behavior of different slenderness ratio columns. The behavior of these
columns in confinement was discussed.
Experimental results indicate that the compression force capacity is affected by
slenderness ratio of the column. For slender column the overall buckling was observed
while for the short columns the crushing and the local buckling is the dominant failure
shape.

Skin Cancer Prognosis Based on Color Matching and Segmentation of Pigmented Skin Lesion

Muthana H. Hamd; Laith M. Mohamad

Engineering and Technology Journal, 2013, Volume 31, Issue 12, Pages 2343-2356

This work develops a new computerized vision of skin cancer diagnosis based on
color matching of pigmented skin lesion and some parameters of ABCD method.
Initially, the clinical diagnostic criteria have been translated to mathematical
concepts. So the lesion edge detection; symmetry; even-symmetry; and segmentation
are computed. Then, the suspicious images would be classified into one of three
categories: benign (mole), malignant (melanoma/non-melanoma), or unknown tumor
using image profile information. The remaining malignant images (melanoma, Basal
Cell Carcinoma, or Squamous Cell Carcinoma) would be further classified using
matching procedure for color spectrums (Red, Yellow, Brown, Black/Gray) with
lesion pigment. The lesion image is segmented into four quarters and the matching
procedure of 120 spectrums is started searching for better result with mean squared
error less than 0.003. The software has been tested over 40 classified images and it
successfully re-classified 92%. This result could be improved if lesion quarters and/or
spectrums are increased.

The Production of Self-Compacting Concrete with Normal Cement Content

Luma A. G. Al- Rawi; Tariq S. Al-Attar; Shakir A. Al-Mishhadani

Engineering and Technology Journal, 2009, Volume 27, Issue 2, Pages 310-320

The main object of this work is to evaluate the possibility for using reasonable cement
content and fine materials to reduce costs of expensive chemical admixtures needed for the
manufacturing of self-compacting concrete (SCC). In this work, three values of cement content
are used (rich, medium and lean mixes) with cement content of 400, 300 and 250 kg/m3
respectively . Two maximum aggregate sizes of (10 and 20mm) for each cement content are
used. The powder content material is (cementations + filler ) is maintained constant (500kg/m3)
while the W/cm ratio ranges from 0.43 to 0.68. 10% Reactive Metakaolin Class N is used as a
partial replacement by weight of cement. On the other hand, limestone dust was used as a
partial replacement by weight of the powder content Tests were carried out on all mixes to
obtain the properties of fresh concrete in terms of viscosity and stability. The results showed that
increasing the percentage of filler (limestone dust) from 20% in rich mixes to50% in lean mixes
of the total weight of the powder content reduces the amount of cement in SCC without
significant effect on the fresh properties of the SCC mixes. This conclusion is significant from
the economical point of view. The mechanical properties of hardened SCC mixes are also
assessed. (compressive strength, modulus of elasticity ). The results obtained from this work
show that it is possible to produce SCC with different levels of cement content (250 to400kg/m3)
using local available materials which satisfy the requirements of this type of concrete .The test
data collected indicate that these materials can be used in the manufacturing of economical SCC.