Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Steel Fibers

Effect of Adding Recycled Sand and Fines Retained from Eggshell Waste on the Mechanical Properties and Durability of SCC and SFSCC

Chaib. S; Bensalem. R

Engineering and Technology Journal, 2023, Volume 41, Issue 5, Pages 1-13
DOI: 10.30684/etj.2023.137162.1340

This scientific research was carried out within the framework of contributing to the recovery different of natures of waste, and making it possible to minimize using of natural aggregates in the field of construction, in order to place an eco-self-consolidating concrete (eco-SCC). Crushed demolition waste mainly of concrete had been studied as a substitute for natural sand. As well as the effect of replacing fines with crushed eggshell waste was assessed. So this present work fits in these contexts. Therefore the main objective of this study is to improve current knowledge on the behavior of studied concretes in the fresh state: slump-flow test, and hardened state: mechanical resistances in compression and in bending, as well as water absorption by capillarity test, absorption by total immersion, and porosity accessible to the water of SCCs designed from different types of waste, recycled sand, and eggshell fines. Also, the method of assessing mixes were affected by the sort of chemical attack, namely the (NaCl) attack was investigated. In light of the obtained results, it was found that the addition of eggshell fines in adequate quantity, can improve the properties of SCCs, in this study a volume of 30% was sufficient, increasing the volume added to 60% introduced an opposite effect. Using recycled sand in this study did not contribute to a significant effect on the mechanical properties of the mixtures studied, although an improvement in workability was observed.

Nonlinear Finite Element Analysis of Fiber Reinforced Concrete Slabs

Saad A. Al-Taan; Ayad A. Abdul-Razzak

Engineering and Technology Journal, 2021, Volume 39, Issue 3A, Pages 426-439
DOI: 10.30684/etj.v39i3A.1641

This paper presents a study on the behavior of fiber reinforced concrete slabs using finite element analysis. A previously published finite element program is used for the nonlinear analysis by including the steel fiber concrete properties. Concrete is represented by degenerated quadratic thick shell element, which is the general shear deformable eight node serendipity element, and the thickness is divided into layers. An elastic perfectly plastic and strain hardening plasticity approach are used to model the compression behavior of concrete. The reinforcing bars were smeared within the concrete layers and assumed as either an elastic perfectly plastic material or as an elastic-plastic material with linear strain hardening. Cracks initiation is predicted using a tensile strength criterion. The tension stiffening effect of the steel fibers is simulated using a descending parabolic stress degradation function, which is based on the fracture energy concept. The effect of cracking in reducing the shear modulus and the compressive strength of concrete parallel to the crack direction is considered. The numerical results showed good agreement with published experimental results for two fibrous reinforced concrete slabs.

Torsional Behavior of Solid and Hollow Core Self Compacting Concrete Beams Reinforced with Steel Fibers

Tareq S. Al-Attar; Sarmad S. Abdul Qader; Hind A. Hussain

Engineering and Technology Journal, 2019, Volume 37, Issue 7A, Pages 248-255
DOI: 10.30684/etj.37.7A.5

Torsion of structural members and the behavior of steel fiber self- compacting reinforced concrete became the area of interest for many researchers nowadays. The experimental program of the present work consists of casting nine reinforced self-compacting concrete beams in three groups. Each group consists of three beams with the dimensions of 200×300×1500 mm. The first beam has a solid cross-section, the second beam has a hollow core with the dimensions of 60×120×1500mm and the last beam has a hollow core with the dimensions of 80×180×1500mm. The steel fiber contents were 0, 0.5 and 1.0 % by volume for first, second and third groups respectively. The torsional angle of twist versus torsional moment (torque) of each beam was found during the experiments, and the effect of variables, fibers volume fraction and section geometry, on this relationship was investigated. Moreover, the fresh and hardened properties of concrete were carried out using several tests, which included slump flow, L-Box, compressive strength, tensile strength, and finally the torsion test. The current results showed that the addition of steel fibers has improved the torsional strength for all beams and the fibers were more effective in hollow core sections than in the solid ones.

Workability of Hybrid Fiber Reinforced Self-Compacting Concrete

Tareq S. Al-Attar; Samer F. Daoud; Anmar S. Dhaher

Engineering and Technology Journal, 2018, Volume 36, Issue 2A, Pages 111-116
DOI: 10.30684/etj.36.2A.1

The aim of this work is to evaluate the effect of adding different types of fibers on the fresh properties of the self-compacting concrete, SCC. The used types of fibers were steel (with volume ratios of 0.75, 1.0 and 1.25 %) and polypropylene fibers (0.10 and 0.15 %) and a hybrid system of these fibers (0.65 % steel and 0.10 % polypropylene). The conducted tests in the fresh state were slump flow, T500, V-funnel and L-box. It was noticed that increasing the volume fraction of fibers would lead to decrease in the workability of SCC. According to EFNARC requirements for SCC, many test results were nonconforming. It was also concluded that polypropylene fibers have higher detrimental effect on fresh properties of SCC than steel fibers and that was attributed to the ability of polypropylene to absorb part of mixing water.

Experimental Research on Tension Lap Splice in Reactive Powder Concrete Beams Exposed to Repeated Loading

Q.A-M. Hassan; H.M. AlHassani; F.F. Saleem

Engineering and Technology Journal, 2017, Volume 35, Issue 5, Pages 479-484
DOI: 10.30684/etj.35.5A.7

This research is a part of an experimental study to examine the effect of lap splicing tension steel bars reactive powder concrete (RPC) beams under repeated loads. Eight RPCbeams whose tension steel bars were spliced at mid-span for a length equals 20 times the bar diameter and one RPC beam without lap splice were casted and tested. These beams were simply supported and tested up to failure under the action of two point repeated loads. The studied parameters were: the steel fiber volumetric ratio (1.5%,1.75% and2%), diameter of tension steel bars (12mm, 16mm and 20mm) and the repeated loading regime in which three types of loading were used depending on the minimum to maximum ratio of the applied load. The first loading regime with ratio of 0% with 0 kN for the minimum load while the maximum was the load beyond that causes yielding of steel bars and this is determined from the previous monotonic load test. The second type with 27% ratio (30 kN for the minimum and 105-110 kN for the maximum). The last type was with 20% ratio (the minimum12 kN and the maximum 60 kN).It should be mentioned that 10mm bar diameter was used to the top reinforcement and stirrups for all beams. The mid-span deflection as well as cracks propagation were recorded for each beam throughout the test. The main results showed that the adopted spliced length of tension steel bars was sufficient in monotonic load but insufficient under the action of high number of cycles of the repeated load. In addition, there were beams of splice failure that having low steel fiber ratio or larger diameter of tension steel bars.

Effect of Steel Fibers, Polypropylene Fibers and/ or Nanosilica on Mechanical Properties of Self-Consolidating Concrete

Iqbal N. Gorgis; Maan S. Hassan; Rana T. Abdulkareem

Engineering and Technology Journal, 2016, Volume 34, Issue 3, Pages 527-538
DOI: 10.30684/etj.34.3A.8

This research concerned studying the combined effect of using nano-silica and/ or hybrid fibers on key mechanical properties of self-consolidating concrete SCC. A comprehensive experimental work has been carried out, using steel fiber (SF) with volume fraction (0, 0.5% and 1.5%), polypropylene fiber (PPF) (0%, 0.05% and 0.15%) and SiO2 nanoparticles (0%, 2% and 4%) by weight of powdered material (silica fume- Sf ) with constant w/c ratio (0.48) to produce eleven different mixtures and tested at different ages (7, 28 and 90 days).
Results showed that adding fibers adversely affect SCC workability and thus more dosage of super plasticizer (SP) should be added to stay within the standard limits. comparable to conventional concretes, the presence of steel fibers with SCC provide slight increase in compressive strength at 28 days, (up to 11%), while significant enhancement in tensile properties were observed (up to 24% and 32% for splitting and flexural strength respectively). Polypropylene or hybrid fibers however, provide lower enhancement compared with steel fibers. In contrast, implementation of nanosilica leads to significant improvement in concrete strengths particularly at 4% dosage. Combined effect of 4% nanosilica and 1.5% of steel fibers provide the superior hardening effect on the flexural performance compared with softening effect provided by other added dosages. Scanning Electron Micrograph (SEM) images confirm the matrix densification effect due to nanosilica adding. Flexural strength of SCCs without nanosilica was generally higher than splitting testing results. This fact does not change even with the presence of nanosilica and/ or fibers.

Mechanical Properties of High Performance Fiber Reinforced Concrete

Wasan Ismail Khalil; Ikbal Naeem Gorgis; Zeinab Raad Mahdi

Engineering and Technology Journal, 2013, Volume 31, Issue 7, Pages 1365-1387
DOI: 10.30684/etj.31.7A10

An experimental work was carried out to produce high performance concrete (HPC) using superplasticizer and silica fume reinforced with fiber. The variables studied were fibers type (steel fibers and polypropylene fibers), aspect ratio of steel fibers (60 and 100) and fiber volume fraction (0.0%, 0.5%, and 0.75%). The effect of fibers on the mechanical properties (compressive strength, splitting tensile and flexural strength, static modulus of elasticity, toughness, and resilience) of normal strength and high performance concrete was also studied. The results show that the optimum dosage of silica fume is 5% as addition by weight of cement with superplasticizer dosage 2 liter/100kg of cement. This dosage of silica fume improves the compressive strength of concrete by about 25% relative to concrete mix without silica fume. The addition of steel fibers causes a slight increase in compressive strength of HPC as fiber volume fraction increases, while the compressive strength decreases as fiber aspect ratio increases. Both splitting tensile and flexural strengths show a significant increase as the fiber volume fraction and aspect ratio increases. The percentage increase in compressive, splitting tensile and flexural strengths for HPC with steel fiber volume fraction 0.75% and aspect ratio 100 at age 60 days is about 9%, 75%, 64%, while for HPC containing polypropylene fiber with volume fraction 0.5% is about 8.5%, 2%, 0% respectively relative to non fibrous HPC.