scholarly journals Performance of full scale self consolidating concrete structural elements in shear, bond and under corrosion attack

2021 ◽  
Author(s):  
Assem adel abdel Aal Hassan
Keyword(s):  
Mass Loss ◽  
Chloride Ion ◽  
Shear Resistance ◽  
Full Scale ◽  
Bond Stress ◽  
Corrosion Performance ◽  
Half Cell ◽  
Cell Potential ◽  
Self Consolidating Concrete ◽  
Beam Depth

This research program focuses on investigating the shear resistance, bond characteristics, and corrosion performance of self-consolidating concrete (SCC) compared to those of normal concrete (NC). The shear strength, cracking behavior, and deflection characteristics were tested in full-scale beams. A total of twenty reinforced concrete beams, with no shear reinforcements, were tested under mid-span concentrated load until shear failure occurred. The experimental test parameters included concrete type/coarse aggregate content, beam depth and the longitudinal reinforcing steel ratio (ρw). The beam depth ranged from 150 to 750 mm while the shear span-to-depth ratio (a/d) was kept constant in all beams, The two longitudinal reinforcing steel ratios used were 1% and 2%. The performance of SCC/NC beams was evaluated based on the results of crack pattern, crack widths, loads at the first flexure/diagonal cracking, ultimate shear resistance, post-cracking shear resistance/ductility, load-deflection response, and failure modes. Code-based equations or procedures are used to predict the crack width, first flexural cracking moment/load, and ultimate shear resistance as well as to simulate load-deflection response. The bond strength of reinforcing bars embedded in full-scale heavy reinforcing beams (4000 mm length x 1200 mm depth x 300 mm width) made with SCC was investigated and compared with that of NC. The flowability of SCC mixture through the dense reinforcement was visually monitored from a transparent formwork. The bond stress was tested for bars located at three different heights (150 mm, 510 mm, and 870 mm from the bottom of the beam) and at different concrete ages (1, 3, 7, 14 and 28 days). The bond stress-free end slip relationship, the top bar effect, and the effect of age on bond stress were investigated in both SCC and NC beams. Bond stresses predicted based on some major Codes were compared with those obtained from experiments. The corrosion of steel reinforcement embedded in full-scale SCC beams was investigated and compared to that embedded in NC beams. The corrosion performance of 400 mm width x 363 mm depth x 2340 mm length beams containing epoxy and non-epoxy coated stirrups was monitored by partial immersion in a sodium chloride solution and an impressed current. Half-cell potential tests were implemented at 25 different locations on each beam to evaluate the probability of steel corrosion along the beam length/perimeter. At the same locations where the half-cell potential tests were implemented, the chloride ion content near the bar surface was measured to study the variation of the chloride-ion penetrability along the beam length/perimeter. The mass loss and bar diameter degradation along the length of each bar were investigated at the end of the test. Predicted rebar mass loss due to corrosion based on Faraday’s law was compared with experimental mass loss for each beam.

scholarly journals Performance of full scale self consolidating concrete structural elements in shear, bond and under corrosion attack

2021 ◽  
Author(s):  
Assem adel abdel Aal Hassan
Keyword(s):  
Mass Loss ◽  
Chloride Ion ◽  
Shear Resistance ◽  
Full Scale ◽  
Bond Stress ◽  
Corrosion Performance ◽  
Half Cell ◽  
Cell Potential ◽  
Self Consolidating Concrete ◽  
Beam Depth

This research program focuses on investigating the shear resistance, bond characteristics, and corrosion performance of self-consolidating concrete (SCC) compared to those of normal concrete (NC). The shear strength, cracking behavior, and deflection characteristics were tested in full-scale beams. A total of twenty reinforced concrete beams, with no shear reinforcements, were tested under mid-span concentrated load until shear failure occurred. The experimental test parameters included concrete type/coarse aggregate content, beam depth and the longitudinal reinforcing steel ratio (ρw). The beam depth ranged from 150 to 750 mm while the shear span-to-depth ratio (a/d) was kept constant in all beams, The two longitudinal reinforcing steel ratios used were 1% and 2%. The performance of SCC/NC beams was evaluated based on the results of crack pattern, crack widths, loads at the first flexure/diagonal cracking, ultimate shear resistance, post-cracking shear resistance/ductility, load-deflection response, and failure modes. Code-based equations or procedures are used to predict the crack width, first flexural cracking moment/load, and ultimate shear resistance as well as to simulate load-deflection response. The bond strength of reinforcing bars embedded in full-scale heavy reinforcing beams (4000 mm length x 1200 mm depth x 300 mm width) made with SCC was investigated and compared with that of NC. The flowability of SCC mixture through the dense reinforcement was visually monitored from a transparent formwork. The bond stress was tested for bars located at three different heights (150 mm, 510 mm, and 870 mm from the bottom of the beam) and at different concrete ages (1, 3, 7, 14 and 28 days). The bond stress-free end slip relationship, the top bar effect, and the effect of age on bond stress were investigated in both SCC and NC beams. Bond stresses predicted based on some major Codes were compared with those obtained from experiments. The corrosion of steel reinforcement embedded in full-scale SCC beams was investigated and compared to that embedded in NC beams. The corrosion performance of 400 mm width x 363 mm depth x 2340 mm length beams containing epoxy and non-epoxy coated stirrups was monitored by partial immersion in a sodium chloride solution and an impressed current. Half-cell potential tests were implemented at 25 different locations on each beam to evaluate the probability of steel corrosion along the beam length/perimeter. At the same locations where the half-cell potential tests were implemented, the chloride ion content near the bar surface was measured to study the variation of the chloride-ion penetrability along the beam length/perimeter. The mass loss and bar diameter degradation along the length of each bar were investigated at the end of the test. Predicted rebar mass loss due to corrosion based on Faraday’s law was compared with experimental mass loss for each beam.

Anticorrosion Performance and Field Application of a New Rebar Inhibitor

2013 ◽  
Vol 310 ◽  
pp. 95-100
Author(s):  
Zhou Yang Lian ◽  
Jun Cheng Jiang ◽  
Dong Sheng Chen ◽  
Wu Ji Wei ◽  
Yong Zhang Zhou
Keyword(s):  
Weight Loss ◽  
Chloride Ion ◽  
Field Application ◽  
Ion Content ◽  
Half Cell ◽  
Cell Potential ◽  
Concrete Pipe ◽  
Long Time ◽  
Anticorrosion Performance ◽  
Chlorine Ion

The anticorrosion performance and field application of a new rebar inhibitor were evaluated through the tests of half-cell potential and weight loss. The results indicated that half-cell potential of rebar had a negative shift with the addition of chloride ion, so it took long time to reach the stable potential. With the increase of chloride ion in the system, half-cell potential was more difficult to achieve stability. When chlorine ion content was low, inhibition effect was very obvious. Inhibition efficiency was 85.53% without chlorine ion and 85.74% with 1.0%NaCl by weight loss. New Rebar Inhibitor had no effect on the mechanical properties of concrete, which had good protective effect on concrete pipe rack in using.

Quantifying chloride-induced corrosion from half-cell potential

1993 ◽  
Vol 23 (6) ◽  
pp. 1443-1454 ◽  
Author(s):  
R.K. Dhir ◽  
M.R. Jones ◽  
M.J. McCarthy
Keyword(s):  
Half Cell ◽  
Cell Potential ◽  
Chloride Induced Corrosion

scholarly journals Influence of coarse aggregate on shear resistance of self-consolidating concrete beams

2017 ◽  
Vol 10 (1) ◽  
pp. 30-40
Author(s):  
G. SAVARIS ◽  
R. C. A. PINTO
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Self Consolidating Concrete ◽  
Coarse Aggregates ◽  
Lower Shear ◽  
Nominal Size ◽  
High Flowability

Abstract Self-consolidating concrete is characterized by its high flowability, which can be achieved with the addition of superplasticizer and the reduction of the amount and size of coarse aggregates in the concrete mix. This high flowability allows the concrete to properly fill the formwork without any mechanical vibration. The reduction in volume and particle size of the coarse aggregates may result in lower shear strength of beams due to a reduced aggregate interlock. Therefore, an experimental investigation was conducted to evaluate the influence of the reduction in the volume fraction and the nominal size of coarse aggregate on concrete shear strength of self-consolidating beams. Six concrete mixes were produced, four self-consolidating and two conventionally vibrated. A total of 18 beams, with flexural reinforcement but without shear reinforcement were cast. These beams were tested under a four-point loading condition. Their failure modes, cracking patterns and shear resistances were evaluated. The obtained shear resistances were compared to the theoretical values given by the ACI-318 and EC-2 codes. The results demonstrated a lower shear resistance of self-consolidating concrete beams, caused mainly due to the reduced aggregate size.

scholarly journals A novel one-sided push-out test for shear connectors in composite beams

2018 ◽  
Author(s):  
Mohammed Abdulhussein Al-Shuwaili ◽  
Alessandro Palmeri ◽  
Maria Teresa Lombardo
Keyword(s):  
Shear Resistance ◽  
Composite Beams ◽  
Full Scale ◽  
Bending Tests ◽  
Shear Connectors ◽  
Shear Connections ◽  
European Standards ◽  
Headed Stud ◽  
The Relationship ◽  
Push Out

Push-out tests (POTs) have been widely exploited as an alternative to the more expensive full-scale bending tests to characterize the behaviour of shear connections in steel-concrete composite beams. In these tests, two concrete slabs are typically attached to a steel section with the connectors under investigation, which are then subjected to direct shear. The results allow quantifying the relationship between applied load and displacements at the steel-concrete interface. Since this relationship is highly influenced by the boundary conditions of POT samples, different experimental setups have been used, where the slabs are either restricted or free to slide horizontally, as researchers have tried to reduce any discrepancy between POT and full-scale composite beam testing. Based on a critical review of various POT configurations presented in the dedicated literature, this paper presents an efficient one-sided POT (OSPOT) method. While OSPOT and POT specimens are similar, in the proposed OPSPOT setup only one of the two slabs is directly loaded in each test, and the slab is free to move vertically. Thus, two results can be obtained from one specimen, i.e. one from each slab. A series of POTs and OSPOTs have been conducted to investigate the behaviour and the shear resistance of headed stud connectors through the two methods of testing. The results of this study than were compared with those of different POTs setups conducted by other researchers. The new OSPOT results show in general an excellent agreement with the analytical predictions offered by both British and European standards, as well as the estimated shear resistance proposed other researchers in the literature. These findings suggest that the proposed one-sided setup could be used as an efficient and economical option for conducting the POT, as it has the potential not only to double the number of results, but also to simplify the fabrication of the samples, which is important in any large experimental campaign, and to allow testing with limited capacity of the actuator. 

Shear and flexural behaviour of lightweight self-consolidating concrete beams

2021 ◽  
Author(s):  
Kokilan Sathiyamoorthy
Keyword(s):  
Shear Strength ◽  
Crack Width ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Normal Weight ◽  
Shear Behaviour ◽  
Flexural Behaviour ◽  
Self Consolidating Concrete ◽  
Shear Span ◽  
Flexural Performance

Shear and flexural behaviour of lightweight self-consolidating concrete (LWSCC) beams made of slag aggregates were investigated. Shear reinforced LWSCC beams showed similar shear behaviour compared to their non-shear reinforced counterparts until the formation of diagonal cracks but higher ultimate shear resistance and ductility. Compared to normal weight self-consolidating concrete (SCC) ones, non-shear reinforced LWSCC beams showed lower post-cracking shear resistance. Shear strength of LWSCC/SCC beams increased with the decrease of shear span to depth ratio. LWSCC beams showed higher number of cracks and wider crack width at failure than their SCC counterparts. LWSCC beams developed higher number of cracks with wider crack width at failure compared with their SCC counterparts. American, Canadian and British Codes were conservative in predicting shear strength of shear/non-shear reinforced LWSCC beams. LWSCC beams (with slag aggregate) showed good shear resistance compared with those made of other types of aggregates besides satisfactory flexural performance.

scholarly journals Observational aspects of Wolf-Rayet atmospheres

1995 ◽  
Vol 163 ◽  
pp. 87-95
Author(s):  
I. I. Antokhin
Keyword(s):  
Mass Loss ◽  
Observational Data ◽  
Full Scale ◽  
Radiative Instability ◽  
Loss Rates

Observational data suggest that WR atmospheres must be considered as highly inhomogeneous objects incorporating strong shocks induced by radiative instability and full-scale supersonic turbulence, with relatively small mean mass-loss rates.

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