scholarly journals Impact of Cyclic Loading on Chloride Diffusivity and Mechanical Performance of RC Beams under Seawater Corrosion

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Sen Pang ◽  
Bo Diao ◽  
Yinghua Ye ◽  
Shuxin Chen ◽  
Xin Wang
Keyword(s):  
Cyclic Loading ◽  
Crack Width ◽  
Steel Surface ◽  
Ultimate Load ◽  
Mechanical Performance ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Rc Beams ◽  
Chloride Diffusivity

An experimental study was conducted to investigate the impact of cyclic loading on the mechanical performance and chloride diffusivity of RC beams exposed to seawater wet-dry cycles. To induce initial damage to RC beam specimen, cyclic loading controlled by max load and cycles was applied. Then beam specimens underwent 240 wet-dry cycles of seawater. Results show that the chloride content increased as max load and cycle increased. The chloride content at steel surface increased approximatively linearly as average crack width increased. Moreover, the max load had more influence on chloride content at steel surface than cycle. The difference of average chloride diffusion coefficient between tension and compression concrete was little at uncracked position. Average chloride diffusion coefficient increased as crack width increased when crack width was less than 0.11 mm whereas the increasing tendency was weak when crack width exceeded 0.11 mm. The residual yield load and ultimate load of RC beams decreased as max load and cycle increased. Based on univariate analysis of variance, the max load had more adverse effect on yield load and ultimate load than cycle.

scholarly journals Chloride Diffusivity and Life Prediction of Cracked RC Beams Exposed to Different Wet-Dry Ratios and Exposure Duration

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jieqiong Wu ◽  
Bo Diao ◽  
Yinghua Ye ◽  
Xiaoning Zheng
Keyword(s):  
Exposure Duration ◽  
Crack Width ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Residual Service Life ◽  
Chloride Ingress ◽  
Rc Beams ◽  
Chloride Diffusivity ◽  
Steel Bar ◽  
Residual Service

Effects of crack width, wet-dry ratio, and exposure duration of wet-dry cycles on chloride ingress of RC beams were experimentally studied. Crack widths of 40, 70, 90, and 120 microns were, respectively, induced by three-point flexural loading and four wet-dry ratios (seawater spraying 1 d in one wet-dry cycle) of 1 : 3, 1 : 7, 1 : 11, and 1 : 15 were selected. Chloride contents of RC beams were tested every 32 d (or 16 d) of wet-dry cycles. Results show that chloride content increased significantly when crack width was larger than 90 microns and wet-dry ratio was 1 : 3, and it increased slightly when crack width was 120 microns and wet-dry ratio was 1 : 7, 1 : 11, and 1 : 15. The chloride content on steel bar surface became the largest when crack width was less than 90 microns and wet-dry ratio was 1 : 7, and while crack width was equal to or greater than 90 microns and wet-dry ratio was 1 : 3, it was the largest. Based on the testing results, chloride diffusion model and prediction model of residual service life of RC beams were suggested considering combined effects of crack width and exposure duration. The predicted residual service lives were corresponding well with experimental results and they decreased as crack width increased.

scholarly journals Durability and Aesthetics of Architectural Concrete under Chloride Attack or Carbonation

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 839 ◽  
Author(s):  
Chang ◽  
Wang ◽  
Jin ◽  
Li ◽  
Feng ◽  
...  
Keyword(s):  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Tidal Zone ◽  
Aesthetic Appearance ◽  
Free Chloride ◽  
Carbonation Resistance ◽  
Chloride Resistance ◽  
Chloride Attack ◽  
The Aesthetic

Architectural concrete has been wildly used nowadays, and those served in an offshore environment often suffer from chloride penetration and carbonation. To assess the protection and decoration performances of architectural concrete, this study exposed architectural concrete to actual marine environments and accelerated carbonation conditions. The chloride and carbonation resistance of architectural concrete was determined to evaluate the protection performance, and the corresponding surface-color-consistency was adopted to characterize its decoration performance. The results show that the total and free chloride of concrete in the marine atmosphere zone and the tidal zone generally decreases with depth; chloride content arguments significantly with exposure time, with a chloride maximum peak near the surface. Moreover, the chloride diffusion coefficient is small throughout the measurements, indicating the superior chloride resistance of architectural concrete. Furthermore, architectural concrete also possesses excellent carbonation resistance based on the carbonation depth data obtained from the carbonation experiment. Therefore, architecture concrete served as protection covers can withstand both the chloride attack and carbonation tested in this paper. In addition, carbonation was found to have a profound influence on the aesthetics of architectural concrete. Therefore, carbonation should be carefully handled for better maintaining the aesthetic appearance of architectural concrete in long-term service.

Testing for the Influence of the Degree of Water Saturation of Concrete upon Chloride Diffusivity

2013 ◽  
Vol 405-408 ◽  
pp. 2639-2643
Author(s):  
Van Tuan Le ◽  
Yong Lai Zheng ◽  
Shu Xin Deng
Keyword(s):  
Diffusion Coefficient ◽  
Water Saturation ◽  
Chloride Ion ◽  
Test Method ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Ion Diffusion ◽  
Chloride Diffusivity ◽  
Water Saturated ◽  
The Impact

In order to estimate the impact of the degree of water saturation of concrete to chloride ion diffusion coefficient, the experimental setup allows to measure chloride diffusion coefficient through nonsaturated concrete specimens with controlled degree of water saturated. The different degrees of water saturation of concrete specimens were obtained, by using saturated solutions of NaCl and KCl controlling the relative humidity, then applied Rapid Cloride Permeability Test method to measure the cloride diffusion coefficient. The test results show that chloride diffusion coefficient depends strongly on the degree of water saturation of concrete. Beside, this relationship shows the non-linear relationship, in which, chloride diffusion coefficient reachs the maximum value in fully saturated concrete specimens.

Influence of Pore Structure on Chloride Distribution in Surface Layer of Cement Paste under Cyclic Wet-Dry Condition

2018 ◽  
Vol 875 ◽  
pp. 165-173
Author(s):  
Hong Lei Chang ◽  
Song Mu ◽  
Ya Ya Du ◽  
Li Yang
Keyword(s):  
Surface Layer ◽  
Pore Structure ◽  
Cement Paste ◽  
Pore Diameter ◽  
Total Porosity ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Profiles ◽  
Peak Value

This research focuses on influence of pore structure on chloride distribution in surface layer of cement paste under cyclic wet-dry condition. The results of chloride distribution reveal that drying and wetting cycles can lead to a peak value of chloride content (Cmax) occurring in surface layer of cement paste. Cmax increases with the increase of W/C. While the depth (Δx) at which Cmax appears does not show a regular change. Moreover, Cmax should be used to predict service life of concrete structures when Cmax appears in the chloride profiles. For the influence of pore structure, there exists an obvious hyperbolic relationship between chloride diffusion coefficient (D), Cmax and pore structure parameters. D and Cmax increase with total porosity and the most probable pore diameter, decrease with tortuosity, and stabilize gradually. And the most probable pore diameter has the most significant impact on D and Cmax. In addition, XRD and SEM-EDS results indicate that the deposition of Friedel’s salt results in the formation of more inkbottle shaped pores, which may cause the appearance of Cmax under cyclic drying-wetting conditions due to hysteretic moisture effect.

scholarly journals Mechanical Performance and Chloride Diffusivity of Cracked RC Specimens Exposed to Freeze-Thaw Cycles and Intermittent Immersion in Seawater

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Bei Shen ◽  
Yinghua Ye ◽  
Bo Diao ◽  
Xiaoning Zheng
Keyword(s):  
Crack Width ◽  
Ultimate Load ◽  
Mechanical Performance ◽  
Exposure Period ◽  
Chloride Ingress ◽  
Rc Structures ◽  
Yield Load ◽  
Compression Load ◽  
Freeze Thaw ◽  
Deicing Salts

The effects of crack width on chloride ingress and mechanical behavior of reinforced concrete (RC) specimens were experimentally studied after exposure to 300 cycles of freeze-thaw and seawater immersion (75 times). Cracks were induced prior to exposure by an eccentric compression load which was sustained until the end of the exposure period. The maximum cracks widths induced in the four column specimens were 0, 0.06, 0.11, and 0.15 mm, respectively. Results show that when the crack width was less than 0.06 mm, the effect of cracks on chloride ingress could be neglected. However, when the crack width was more than 0.11 mm, chloride ingress was accelerated. Results of static loading tests show that both yield load and ultimate load of RC columns decreased as crack width increased. When the crack width was 0.15 mm, yield load and ultimate load of RC column specimen decreased by 17.0% and 18.9%, respectively, compared to a specimen without cracks. It was concluded that crack width significantly promoted local chloride ingress and mechanical performance degradation of RC structures in cold coastal regions or exposed to deicing salts.

Experimental Study on the Chloride Diffusivity of Recycled Aggregate Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1404-1408
Author(s):  
He Ying Qin ◽  
Yan Lin Zhao ◽  
Bo Guang Luo ◽  
Yi Hu Chen
Keyword(s):  
Diffusion Coefficient ◽  
Fly Ash ◽  
Silica Fume ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chloride Diffusion ◽  
Partial Replacement ◽  
Chloride Diffusion Coefficient ◽  
Aggregate Concrete ◽  
Chloride Diffusivity

The study presented herein has been carried out in order to investigate the chloride diffusivity of recycled aggregate concrete (RAC). Meanwhile, the effect of the binder type, involving cement replacement materials such as, fly ash, slag and silica fume on the chloride diffusivity has also been investigated. For this purpose, RAC and concrete containing the different type of binders with w/b ratios of 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 were used. As a result, the chloride diffusion coefficient of RAC is higher than that of natural concrete and the partial replacement of cement with fly ash, slag and silica fume is effective in decrease in the chloride diffusion coefficient, measured by a rapid chloride conductivity test.

scholarly journals Combined Effect of Initial Curing Temperature and Crack Width on Chloride Penetration in Reinforced Concrete Beams

2018 ◽  
Vol 142 ◽  
pp. 02003
Author(s):  
Lotfi Elkedrouci ◽  
Bo Diao ◽  
Sen Pang ◽  
Yi Li
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Chloride Ion ◽  
Chloride Content ◽  
Chloride Penetration ◽  
Reinforced Concrete Beams ◽  
Curing Temperature ◽  
Chloride Diffusion ◽  
Rc Structures ◽  
Cover Cracking

Reinforced concrete (RC) structures are gradually being degraded all over the world, largely due to corrosion of the embedded steel bars caused by an attack of chloride penetration. Initial curing would be regarded as one factor influencing chloride diffusion in concrete in combination with cover cracking that is also of great attention for reinforced structures. In this study, a non-steady state diffusion test of chloride ion involving RC beam specimens with a water-to-cement ratio of 0.5, initial curing temperatures of 5°C or 20°C and three types of crack widths ranging from 0 to 0.2mm was performed. Chloride content at 5°C or was determined. The results show that the higher chloride content was obtained in condition of crack width large than 0.1mm with low initial curing temperature and there are no obvious differences in chloride content when the crack width was not larger than 0.1mm.

Experiment and Numerical Study on Shear Capacity of RC Beams

2011 ◽  
Vol 94-96 ◽  
pp. 674-678
Author(s):  
Jun Liu ◽  
Feng Peng Zhang ◽  
Yin Bo Zuo
Keyword(s):  
Cyclic Loading ◽  
Crack Width ◽  
Numerical Study ◽  
Shear Capacity ◽  
Experimental Result ◽  
Rc Beams ◽  
Shear Transfer ◽  
Fem Method ◽  
The Relationship ◽  
Diagonal Crack

Based on cyclic loading experiment of six beams in the two groups, the relationship among the stirrup stress, initial diagonal crack width and shear capacity of RC beams was studied. Experimental result shows that the decline of the shear strength of the RC beams due to cyclic loading can be characterized by the width of diagonal crack, according to the experimental phenomena, a formula for shear capacity after cyclic loading is derived for engineering use. To study the mechanism of the capacity decline, considering the effect of the width of diagonal crack to the shear transfer coefficient, numerical analysis by FEM method was done, the result is compared to the experimental result.

Study on Permeability of Concrete under Sustaining Tension

2010 ◽  
Vol 163-167 ◽  
pp. 3306-3310
Author(s):  
Li Guo Ma ◽  
Yun Sheng Zhang ◽  
Lu Guang Song
Keyword(s):  
Diffusion Coefficient ◽  
Steady State ◽  
Experimental Method ◽  
Experimental Device ◽  
Chloride Diffusion ◽  
Tension Stress ◽  
Diffusivity Coefficient ◽  
Chloride Diffusion Coefficient ◽  
Chloride Diffusivity ◽  
Chloride Migration

An experimental device which provided uniaxial sustaining tension stress to concrete was especially designed with pressed spring. The accelerated, steady state chloride migration experimental method was used to test the permeability of concrete under tension resulting from designed device. Concrete with two mixture proportions was tested to get chloride diffusion coefficient under different tension stress. Mathematics models were built to show the change of chloride diffusivity coefficient of concrete under tension.

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