Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Steel fiber

Shear Strength of Reinforced Fibrous-self Compacted Concrete Box Girder using Recycled Concrete Aggregate

Mohammed A. Hadi; Eyad K. Sayhood; Ali S. Resheq

Engineering and Technology Journal, 2021, Volume 39, Issue 8, Pages 1307-1320
DOI: 10.30684/etj.v39i8.2100

Protection of environmental and conservation of natural resources is a fundamental issue in today’s world. In this research, the shear behavior of reinforced concrete box girders with recycled aggregate (RA), steel fiber, and internal diaphragms were investigated. Eleven reinforced concrete box girders with typical longitudinal and transverse reinforcement were tested under two point loading until failure. The RA was prepared by crushing the collected waste of concrete from the laboratory test cylinders and cubes. The experimental variables considered include; RA percent of 50%, 75%, and 100%(replacing from NA), steel fiber with volumetric ratios (Vf) of 0.5%, 1.0%, and 2%, diaphragm numbers (two and three).The test results revealed that the shear strength of the box girders affected by the RA content, the ultimate load was decreased by (32, 25, and 19) % for the (100, 75, and 50) %RA concrete, respectively in compared with the control specimen. In contrast the steel fiber was more effective in strengthening of the RA concrete specimen, for the (Vf) of 0.5%, 1.0%, and 2.0% with non-fibrous 100% RA concrete, the strengthening were (25, 40, and 77) % respectively. Moreover, when 1.0% steel fibers added to the 100%, 75%, and 50%RA concrete respectively, the strengthening were (40 ,45 ,and48 )% compared  each with its reference specimen.  On the other hand, when two and three diaphragms used, the strengthening for the non-fibrous 100% RA concrete was (6% and 9%) respectively. cracking load, ultimate load, load- deflection, and concrete surface strain has been taken into consideration in this research.

The Effect of the Waste of Materials and Carbon Nanotube on the Concrete Incorporated with Steel Fibers

Mayada H. Saleem; Farhad. M. Othman; Alla A. Abdul-Hameed

Engineering and Technology Journal, 2021, Volume 39, Issue 6, Pages 956-964
DOI: 10.30684/etj.v39i6.2018

The addition of agricultural and industrial solid wastes and nanomaterials to concrete combined with steel fibers to improve the mechanical and electrical properties of concrete was investigated. This approach could be used in advanced applications in electromagnetic shielding and conductive concrete. Steel fibers were used at 2%wt. of sand and (induction furnace slag (EIF), carbon nanotube (CNT), steel wool fibers, prepared corn husks) at 0.5 and 1 wt.%. of cement. Obtained results of using 1% for both carbon nanotube and steel wool with steel fibers in the mixture 4 and 6, respectively, showed the highest rates of compressive strength. A similar result was shown when tested at 3,7 and 28 days of age and compressive strength was 47.4MPa,47.34MPa for the mixture 4 and 6 respectively. The electrical conductivity and electrical resistance of the samples were measured at the age of 7 days. The findings have also shown that adding steel wool as well as( CNT) gave the best results and the sample containing the furnace slag achieved satisfactory results as well.

Direct Shear Strength of RPC Member

Shahad Q. Madhlom; Hussein A. Aziz; Ammar A. Ali

Engineering and Technology Journal, 2021, Volume 39, Issue 1A, Pages 22-33
DOI: 10.30684/etj.v39i1A.1638

In this research paper, results are obtained from Reactive Powder Concrete (RPC) push-off specimens - double L shape subjected to direct shear loading. Different parameters considered are compressive strength, percentages of steel fiber, presence of aggregate and shear reinforcement. The results show that increasing in steel fiber content starting from 0.0% and ending with 1.5% leads to increases in the shear strength by (261%) and attempt to decrease its brittleness. The presence of steel fiber content enhances and improves the tensile strength and the shear strength. Using RPC in constructing the specimens enhances the shear strength by 29.6% compared with NSC specimen.
Shear strength increased by 25% when the compressive strength increased from 75 to 90MPa. The presence of transverse steel rebar in the direction of shear line increased the shear strength by (108.3%) as compare with the specimen without shear rebar. The presence of small aggregate in RPC mix creates an increase in the shear strength by (9.1%).

The Effects of Using Steel Fibers on Self-Compacting Concrete Properties: A Review

Shubbar J. Kadhim

Engineering and Technology Journal, 2020, Volume 38, Issue 11, Pages 1666-1675
DOI: 10.30684/etj.v38i11A.1678

In this literature review, steel fibers reinforced self-compacting concrete properties in fresh and hardened states and factors affecting them were reviewed. In spite of the high workability of self- compacting concrete, using steel fibers depending on their length, aspect ratio, shapes and volume fraction can cause detrimental effects on it. Using steel fibers improves hardened properties especially flexural and post-peak performance, and this improvement depends on how fibers can distribute and orientate in the fresh state. The better hardened properties can be obtained when fibres aligned and orientated in the direction parallel to tensile stress.

Analysis and Design of Beams Reinforced with Steel Fiber and Composite Plates

Mereen H. Fahmi Rasheed; Ayad Z. Saber Agha

Engineering and Technology Journal, 2020, Volume 38, Issue 2, Pages 113-125
DOI: 10.30684/etj.2021.168181

The addition of epoxy bending plate to the tension and compression faces or web is an effective technique for flexural or shear strengthening of reinforced concrete beams, also using of steel fibers with concrete improves the structural behavior and increases the moment capacity and shear resistance of the beams. General equations are derived for predicting the bending moment capacity, maximum and balancing reinforcement ratio the equivalent depth of the compression zone for singly and doubly reinforced rectangular sections and T-beams. The results indicate that bending moment capacity increased in beams with steel fibers and composite plates, while the maximum balancing reinforcement ratios are decreased.

Slurry Infiltrated Fiber Concrete as Sustainable Solution for Defected Buildings

Mays F. Alrubaie; Dalya H. Hameed; Shakir A. Salih; Galib M. Habeeb; Waleed A. Abbas

Engineering and Technology Journal, 2019, Volume 37, Issue 1C, Pages 132-138
DOI: 10.30684/etj.37.1C.21

One of the new concrete technology applications that had to get increased importance as repairing and retrofitting technique is slurry infiltrated fiber concrete (SIFCON). This research aims to investigate some of the mechanical properties of SIFCON and its role in improving the useful life of normal concrete. The research consists of two parts; in the first part, three mixes are prepared with 0%, 1.5%, and 6% volume fraction steel fiber content. Compressive strength, flexural strength, total absorption and apparent density tests are made for each mix. In the second part, a composite section of normal concrete and SIFCON mix with 6% steel fiber is prepared. Different thicknesses of SIFCON layer had been casted to assess its benefits in repair and/or to strengthen of defected buildings. Flexural strength, toughness, ductility and load-deflection curve are examined for the composite sections. The results showed that the flexural strength of SIFCON with 6% steel fiber content increased up to 600% and 200% compering to those recorded with the reference mix and 1.5% steel fiber concrete respectively. The results also indicated that the increase of SIFCON layer thickness would improve the mechanical properties of the composite section. Also, the maximum increase in flexural strength was greater than four times the reference mix. Better behavior is also recorded in load deflection and toughness of SIFCON composite section.

Combined Effect of Silica Fume and Steel Fiber on Modulus of Elasticity of High Performance Concrete

Muntadher J. Taher; Maan S. Hassan; Zeyad M. Al-azawi

Engineering and Technology Journal, 2015, Volume 33, Issue 4, Pages 868-876

Concrete elastic modulus is a basic property required for the appropriatepredicting of its basic behavior and for its correct implementation in a variety ofconstructional and engineering applications. This study presents an experimental and analytical evaluation of elastic modulus of high performance concretes (HPC) produced bysteel fiber and silica fume. The aim of this study is to develop the elastic modulus propertyof HPC and to show the applicability of ACI models to predict the elastic modulus of HPC from compressive strength. Four volume fractions of steel fiber with an 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% by weight as a cement replacement. Water/cement ratio was ranged (0.28-0.4) with different amount of superplasticizer, and the reference slump was 170 mm. Both compressive and elastic modulus tests were made on hardened concretes reinforced with steel fibers and then compared with control specimens at 14 and 28 days. The results showed that the presence of silica fume enhanced the compressive strength and modulus of elasticity of evaluated concretes. In addition, adding steel fiber slightly increased both strength and modulus of elasticity values. Also, results showed that the elastic modulus of HPC is relative to the compressive strength, the ACI 318 expression is predicting elastic modulus of HPC and HPC-SF superior than ACI 363, but ACI 363 equation seems to be better in prediction modulus of elasticity of HPC-SF0.5S, HPC-F1.0S, and HPC-SF2.0S in comparison with ACI 318.