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.

Damage and Chloride Penetration of Cement Mortar under Conventional Triaxial Compression

2011 ◽  
Vol 71-78 ◽  
pp. 744-747
Author(s):  
Zu Quan Jin ◽  
Qiu Yi Li ◽  
Chuan Li ◽  
Tie Jun Zhao
Keyword(s):  
Diffusion Coefficient ◽  
Cement Mortar ◽  
Triaxial Compression ◽  
Axial Loading ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Axial Deformation ◽  
Free Chloride ◽  
Conventional Triaxial Compression

In this paper, the influence of conventional triaxial compression on damage and chloride ion penetration of cement mortar are investigated. Conventional triaxial compression experiment was carried out with confining loading of 10Mpa. And the stress-strain curve was measured when axial stress was 50%, 80% and 100% of peak axial loading, and 80% axial loading post-maximum. Then the damaged cement mortars was stored in Qingdao sea water for 30 days, and the free chloride content as well as chloride diffusion coefficient of damaged mortars were quantitatively determined. The experimental results show that the cement mortar is compacted in the end, and shear damaged in the middle under conventional triaxial compression. Compared to cement mortar under uniaxial compression, its compressive strength and axial deformation increases by 1.94 times and 5.6 times when cement mortar under conventional triaxial compression. When the axial stress is less than 48% of peak axial loading, and the axial deformation is less than 0.63mm, the mortar is compacted and its relative dynamic elastic modulus increases with raising axial loading and deformation. The free chloride content in the pressure-bearing side is higher than that in the bottom side. And the free chloride content in the interior of mortar increases with raising axial loading. The chloride diffusion coefficient and axial loading are related in quadratic function. When the axial deformation of mortar is higher than 0.72mm and 1.57mm, the chloride diffusion coefficient of non-load mortar, is less than that of loaded mortar in the pressure-bearing side, and in the bottom side, respectively.

Chloride Resistance of Recycled Aggregate Concrete under Wetting-Drying Cycles

2016 ◽  
Vol 724 ◽  
pp. 3-7 ◽  
Author(s):  
Bing Qi ◽  
Jian Ming Gao ◽  
Da Man Shen
Keyword(s):  
Chloride Content ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Chloride Diffusion ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Free Chloride ◽  
Chloride Resistance

Recycled aggregates concrete (RAC) becomes an important participant in recycled materials. This study was performed in order to evaluate the effect of recycled coarse aggregates (RCA) on the chloride resistance of concretes with different coarse aggregates replacement ratio under wetting–drying cycles. Composition influence on the concrete were studied with different the addition of admixtures. The results indicate that the free chloride content decreased with the increasing of depth, whist it increased with the increasing replacement ratio of RCA at the same depth. Wetting–drying cycles accelerated the process of chloride diffusion. It was also found that the addition of admixtures can improve the ability of chloride resistance of concrete.

Chloride Diffusion in Limestone Cement Concrete Exposed to Combined Chloride and Sulfate Solutions at Low Temperature

2014 ◽  
Vol 897 ◽  
pp. 171-175 ◽  
Author(s):  
Konstantinos Sotiriadis ◽  
Sotirios Tsivilis ◽  
Vít Petranek
Keyword(s):  
Low Temperature ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Concrete ◽  
Sulfate Content ◽  
Total Chloride ◽  
Sulfate Solutions ◽  
Free Chloride ◽  
Limestone Cement

The chloride diffusion in limestone cement concrete exposed to combined chloride and sulfate solutions at low temperature was studied. For this purpose, a normal Portland cement and two Portland limestone cements (15% and 35% w/w limestone content) were used for concrete preparation. The specimens were immersed in two combined chloride-sulfate solutions of different sulfate content, and stored at 5°C. The total and free chloride contents, as well as the chloride diffusion coefficients were determined for each concrete composition. The results show that the total chloride content and free to total chloride ratio are increased with time. The sulfate content of the corrosive solutions has not a clear effect on total chloride content and chloride diffusion coefficient. It seems that the lower sulfate content results, in general, in higher free to total chloride ratio values. The use of limestone in cement results in higher chloride concentrations in concrete and free to total chloride ratio values. In general, these phenomena are intensified for higher limestone content.

Durability Design of Tunnel Concrete Lining under Chloride Attack

2012 ◽  
Vol 594-597 ◽  
pp. 1014-1017
Author(s):  
Lu Feng Yang ◽  
Hong Bin ◽  
Yu Bo
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Concrete Lining ◽  
Chloride Diffusion Coefficient ◽  
Initial Value ◽  
Durability Design ◽  
Chloride Attack ◽  
Finite Element Formulations

Chloride induced corrosion of reinforcing steel is one of major causes of deterioration of tunnel concrete lining under chloride attack. In this paper, a finite element model for chloride ions transport in tunnel concrete lining was proposed based on the Fick’s second law of diffusion. The governing partial differential equation was solved numerically in space as a boundary-value problem and in time as an initial-value problem by means of the finite element formulations. The maximum allowable value of chloride diffusion coefficient of tunnel concrete lining with service life of 100a was achieved and some constructive suggestions for durability design of tunnel concrete lining under chloride attack were also proposed.

scholarly journals Chloride Resistance of Portland Cement-Based Mortar Incorporating High Aluminate Cement and Calcium Carbonate

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 359 ◽  
Author(s):  
Yunsu Lee ◽  
Seungmin Lim ◽  
Hanseung Lee
Keyword(s):  
Diffusion Coefficient ◽  
Calcium Carbonate ◽  
Pore Volume ◽  
Binding Capacity ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Chloride Binding ◽  
Chloride Resistance ◽  
Aluminate Cement ◽  
Capillary Pore

Whether chloride resistance is highly influenced by chloride binding capacity remains unknown. In this study, the chloride resistance of Portland cement-based mortar incorporating aluminate cement and calcium carbonate was investigated considering the chloride binding capacity, pore structures and chloride diffusion coefficient from non-steady state chloride migration and natural chloride diffusion. The cement hydrates were investigated using X-ray diffraction and thermogravimetric analysis. The chloride binding capacity was evaluated based on the chloride adsorption from the solutions using the adsorption isotherm. The aluminate cement, as an available alumina source, can stimulate the formulation of layered double hydroxides, which in turn can increase the chloride binding capacity. The results of mercury intrusion porosimetry show that non-substituted (control) and substituted (only aluminate cement) specimens have capillary pore volume 8.9 vol % and 8.2 vol %, respectively. However, the specimen substituted with aluminate cement and calcium carbonate shows a higher capillary volume (12.9 vol %), which correlates with the chloride diffusion coefficient. Although the specimen substituted with calcium carbonate has a higher chloride binding capacity than the control, it does not necessarily affect the decrease in the chloride diffusion coefficient. The capillary pore volume can affect not only the chloride diffusion but also the chloride adsorption.

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 Effect of Ammonia-Soda Residue on the Strength and Chloride-Resistance Performance of Steel Slag-Granulated Blast Furnace Slag-Based Concrete after Immersion in Artificial Seawater

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6048
Author(s):  
Chengwen Xu ◽  
Wen Ni ◽  
Keqing Li
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Chloride Ions ◽  
Artificial Seawater ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Friedel’S Salt ◽  
Chloride Resistance ◽  
Furnace Slag

Ammonia-soda residue (ASR) is the main solid waste generated from soda manufacturing and is hard to reuse due to its complex chemical composition. This study investigated the influence of ASR content on the strength and chloride-resistance capacity of concrete based on basic oxygen furnace slag and ground blast furnace slag. The hydration and chloride resistance mechanisms were analysed by comparing the hydrate products and pore structural changes. The results showed that adding ASR had the greatest impact on early strength. ASR-introduced chloride ions may participate in the hydration process to generate Friedel’s salt and decrease ettringite. The optimum pore distribution appeared when the ASR-to-desulphurisation gypsum ratio was 2:3 because of the introduction of nucleation sites and the decrease of C–S–H gels. The two chloride resistance-capacity measurements were affected differently by the ASR content. The apparent chloride diffusion coefficient was mainly affected by the percentage of pores that were larger than 10 nm. However, electric flux increased when ASR increased due to the influence of introduced chloride. The crystallisation pressure of Friedel’s salt decreases the strength of concrete with ASR content after high-concentration artificial-seawater immersion. The significant chloride-resistance property provided an alternative use for the concrete containing ASR.

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.

Microstructure Analysis on LILW Waste Disposal Facility by Accelerated Steel Corrosion Tests

2013 ◽  
Vol 378 ◽  
pp. 194-197
Author(s):  
Ki Beom Kim ◽  
Jang Hwa Lee ◽  
Do Gyeum Kim
Keyword(s):  
Diffusion Coefficient ◽  
Waste Disposal ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Microstructure Analysis ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Reinforcing Bar ◽  
Disposal Facility ◽  
Chloride Attack

Concrete structures such as LILW waste disposal facility located near the sea may suffer from chloride attack damages. This study aims to analysis mock-up test for acceleration corrosion of reinforcing bar and its deterioration in concrete structures by XRD and chloride diffusion coefficient. Corrosion acceleration experiment test has been developed and used to evaluate the effect of corrosion of reinforcing bar caused by seawater on engineered barrier of LILW waste disposal facility.

scholarly journals Influence of Nano-silica and Crack Width on Corrosion Parameters of Pre-cracked Reinforced Concrete Beams

2021 ◽  
Author(s):  
Naser Nosratzehi ◽  
Mahmoud Miri
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Nano Silica ◽  
Diffusion Factor ◽  
Permeability Characteristics ◽  
Chloride Attack

This paper presents an experimental study on the durability of both sound and cracked reinforced concrete (RC) beam specimens. Using nano-silica (NS) can improve the durability properties of reinforced concrete. So, RC beams with three nano-silica percentages of 0 %, 1.5 %, and 3 % were prepared. In addition, to consider the effect of cracking on corrosion, crack widths between 0.1 mm and 0.5 mm, and cover depths of 30 mm and 45 mm were considered. All beam specimens were subjected to 5 % NaCl solution and monitored weekly for half-cell potentials (HCP). The presented results include the HCP evaluation and diffusion factor values in sound and cracked concrete beams exposed to chloride attack. The experimental results indicated that the chloride diffusion coefficient increases with extending crack width. Nano-silica improved the permeability characteristics of concrete, HCP and also diffusion factor values. Regressive models of the chloride diffusion factor and HCP values were proposed for influencing parameters, i.e., nano-silica and crack width with two different cover depths.

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