Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Carbon Fiber

Mechanical Characteristics and Self-Monitoring Technique of Smart Cementitious Mixtures with Carbon Fiber and Graphite Powder as Hybrid Functional Additives

Raid D. Abdullah; Ali Al-Dahawi; Hussein H. Zghair

Engineering and Technology Journal, 2022, Volume 40, Issue 11, Pages 1537-1547
DOI: 10.30684/etj.2022.134097.1220

In this paper, the self-sensing properties of cementitious composites under compressive loads were investigated by utilizing hybrid functional fillers, which are responsible for creating an electrical network that is used to build the self-sensing capability within the traditional cement-based mixtures. Most of the previous works depict the self-sensing capability with the aid of one type of functional fillers or fibers. The present paper attempts to utilize two types of functional fillers, representing a gap filling within the subject. Four hybrid proportions of Graphite (G) (wt.%) and carbon fibers (CF) (vol.%) were introduced. These are (0.5, 1.0), (1.0, 0.75), (1.5, 0.50) and (2.0, 0.25) respectively. In addition to carbon-based materials, polypropylene, polyolefin, and steel fibers are used as reinforcing fibers. One type of fiber was utilized in each manufactured mixture with a constant rate of 2% by volume of the mixture. A plain mixture without functional fillers has also been manufactured. The samples were non-destructively tested by an ultrasonic device before a uniaxial compression test was performed. To verify the self-sensing properties of the manufactured samples, the electrical resistance of the samples was recorded during load application each second. The self-sensing behavior was better for mixtures containing high dosages of graphite with respect to the fractional change in electrical resistivity (FCER). Steel and polyolefin fibers showed good results in terms of compressive strength behavior. However, polypropylene fibers showed the lowest compression strength among all types of reinforcing fibers used.

Investigate the Effect of Different Kinds of Discontinuous Fibers on the Mechanical Properties of Epoxy Matrix Composite Materials

Ahmed Muhammad; Ibrahim A. Atiyah; Hamza M. Kamal; Ahmed M. Al-Mukhtar

Engineering and Technology Journal, 2018, Volume 36, Issue 5A, Pages 520-522
DOI: 10.30684/etj.36.5A.7

The composite manufacturing has been a wide variety of applications. The low density, stiffness, and weight to strength ratio giving these materials significant mechanical properties in aerospace, and automotive industries. In this work, the specimens of fiber reinforced composites have been prepared by adding different percentage of two types of fibers in epoxy resins matrix. So, the aim of this study is to evaluate the effect of additives on the mechanical properties according to Standard Test Method for Tensile Properties ASTM D3039. The tensile and hardness testing show that the carbon fibers improve the hardness and tensile strength due to their higher mechanical properties. In addition, they have high strength to weight ratio as compare with polypropylene fibers.

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).

Mechanical and Physical Properties of Nano Carbon Tube with Carbon Fiber Reinforced with Polyester Resin

M. Subhi; E. S. AL-Hassani; A.B. Abdul-Hussein

Engineering and Technology Journal, 2017, Volume 35, Issue 5, Pages 465-472
DOI: 10.30684/etj.35.5A.5

In this research, study some physical and mechanical properties of polymernano composites. The polymernano composites based on unsaturated polyester resin reinforced with carbon fibers (C.F). The samples are attended by hand lay – up method. The samples constituent were polyester resin as matrix with 3% volume fraction from carbon fiber and (0.5%, 1%, 1.5%, 2 %( volume fractions of carbon nanotube. The water absorption, hardness (shore D), flexural test, impact test and toughness fracture properties are studied. Results showed that water absorption increase with addition 3% volume fraction of carbon fiber and Carbon Nanotube, the sample (polyester+3%C.F+0.5% CNTs) has lower water absorption than other samples. The hardness (shore D), flexural test, impact testand toughness fracture for the sample (polyester+3%C.F+0.5% CNTs) has higher value for Nano- composites.

Study the Effect of Glass and Carbon Fibers on the Firebrick Properties

H.A. Jaber

Engineering and Technology Journal, 2017, Volume 35, Issue 4, Pages 391-398

This work was carried out to investigate effect of glass fiber (GF) and carbon fiber (CF) on kaolin-clay firebrick properties. GF and CF are considered inorganic fibers with application of high temperatures. Kaolin clay is mixed with short GF and CF separately by different percentages (0, 0.5, 1, 1.5 and 2) wt%. Kaolin-GF and kaolin-CF mixtures were compacted by using the semi-dry pressing method. The compacted specimens were fired at different temperatures (1100, 1200 and 1300)°C. Properties which include bulk density, apparent porosity, water absorption, thermal conductivity and fracture strength were obtained from the firebrick specimens. The results show that the addition of GF has beneficial in lowering of firing temperature, and consequently accelerating the densification via enhanced grain boundary diffusivity. Increasing GF content in the firebrick mixture enhances the fracture strength due to increase amount of glassy and mullite phases. Incorporation of CF has inversely affected than GF on the firebrick properties. As the percentage of CF increased the density of firebrick decreased, and the porosity and water absorption increased.

Effect of Al2O3 Powder on Some Mechanical and Physical Properties for Unsaturated Polyester Resin Hybrid Composites Materials Reinforced by Carbon and Glass Fibers

Reem Alaa Mohammed

Engineering and Technology Journal, 2016, Volume 34, Issue 12, Pages 2371-2379
DOI: 10.30684/etj.34.12A.18

This research is a study of the effect of Al2O3 powder on physical and mechanical properties of the polymer hybrid composites based on unsaturated polyester resin reinforced with carbon and glass fibers. The samples were made by a hand lay-up method according to ASTM standard for various volume fractions of additives. The polymer composites materials reinforced with carbon and glass fibers are the most used in manufacture of components such as pip, part of aerospace, and leisure industries and automotive.The polyester resin matrixwas strengthened with 3% carbon and glass fibers with 1%, 3%, 5%, 7% Al2O3 powders. The water absorption, hardness (shore D), impact test, and flexural strength properties are studied. The results show the specimens (UP+3%C.F+7%Al2O3) and(UP+3%G.F+7%Al2O3) had the maximum hardness (shore D) and water absorptionwhen compared withunfilledpolyester resinspecimen, it can be observed that the specimens(UP+3%C.F+5%Al2O3) and (UP+3%G.F+5%Al2O3) have maximum impact strength and flexural strengthcompared with specimens (UP+3%C.F+7%Al2O3)and (UP+3%G.F+7%Al2O3) .

Coating of Carbon Fibers With Calcium Phosphate by Sol- Gel Method

Sewench N. Rafeeq; Wafaa A. Husaien; Russel Rushdi Ghanim

Engineering and Technology Journal, 2014, Volume 32, Issue 5, Pages 1117-1128

Sol-gel technique has been used to coat carbon fibers with calcium phosphate to improve the esthetic of black carbon fibers as it's biocompatible. To improve bonding between carbon fibers and prepared calcium phosphate powders, the surface of carbon fibers has been treated with para-aminobenzoic acid. The structural tests include: (SEM, XRD, AFM and FTIR). The morphology of the coating layers has been examined by scanning electron microscope (SEM). The crystallized phase composition of coatings has been identified by x-ray diffractometry (XRD). The grain size of dried and heat treated calcium phosphate coat has been estimated by atomic force microscope (AFM) and fourier transform ــ infrared spectroscopy (FTIR) analysis which support and verify the x-ray diffraction findings.