Modeling of chloride diffusion in concrete containing low-calcium fly ash

Wang, Xiao-Yong; Lee, Han-Seung

doi:10.1016/j.matchemphys.2012.12.085

Cited by 9 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first one, common to all the studied samples and solutions, was that, with increasing concentrations of the alkaline solution in which the TS was immersed, as well as with increasing temperature of the experimental conditions, a more significant alkali invasion inside the TS occurred. This result was quite expected and also consistent with the results of previous studies on the permeation of chlorides and sulfates as degradation media [ 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. The second result of the observation was the ability of sodium ions to penetrate deeper into the sample mass than was the case with the potassium analog.…”

Section: Resultssupporting

confidence: 93%

See 1 more Smart Citation

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

et al. 2022

View full text Add to dashboard Cite

The possibility of the formation of an alkali–silicate reaction (ASR) is a crucial issue for the service life of concrete. The coexistence of key parameters such as the presence of alkalis, reactive SiO2, humidity, and temperature predetermine the possibility of its formation and application. When an ASR gel forms, it results in the concreting cracking and spalling as well as in the deterioration of its overall properties. The risk of ASR depends on the concentration of alkalis and their mobility, which influence their ability to penetrate the concrete. The objective of this study was to determine the ionic mobility of not only Na+ and K+, but Ca2+ as well, from external sources (0.5 and 1.0 mol/L solutions of Na/K carbonate, nitrate, and hydroxide) to a cementitious matrix as the precursor for ASR. The concentrations of ions in both the immersion solutions (ICP) and the cementitious matrix itself (SEM-EDX) were studied as a function of time, from 0 to 120 days, for leaching, and according to temperature (25 and 40 °C). The reaction products were characterized using SEM-EDX. Different diffusion rates and behavior were observed depending on the anion type of the external alkali source. Both sodium and potassium ions in all the three environments studied, namely carbonate, hydroxide, and nitrate, penetrated into the composite and further into its structure by different mechanisms. The action of hydroxides, in particular, transformed the original hydration products into calcium-silicate-hydrate (CASH) or ASR gel, while nitrates crystallized in pores and did not cause any changes in the hydration product. The driving force was the increased temperature of the experiment as well as the increased concentration of the solution to which the test specimen was exposed.

show abstract

Section: Resultssupporting

confidence: 93%

“…ous studies on the permeation of chlorides and sulfates as degradation media [43][44][45][46][47][48][49]. The second result of the observation was the ability of sodium ions to penetrate deeper into the sample mass than was the case with the potassium analog.…”

Section: Monitoring the Depth Of Diffusion Of Alkali Ions Into The Ts...mentioning

confidence: 99%

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Additional chloride can penetrate into concrete through surface cracked zone. Hence, for durability design of reinforced concrete structures, the considerations of influences of cracking on chloride ingression are necessary [1,2].…”

Section: Introductionmentioning

confidence: 99%

Simulation of Chloride Diffusion in Cracked Concrete with Different Crack Patterns

Wang

Zhang

2016

Advances in Materials Science and Engineering

Self Cite

View full text Add to dashboard Cite

Chloride-induced corrosion of steel rebar is one of the primary durability problems for reinforced concrete structures in marine environment. Furthermore, if the surfaces of concrete structures have cracks, additional chloride can penetrate into concrete through cracked zone. For chloride ingression into cracked concrete, former researches mainly focus on influence of crack width on chloride diffusion coefficients. Other crack characteristics, such as chloride depth, crack shape (equal-width crack or tapered crack), crack density, and spacing, are not studied in detail. To fill this gap, this paper presents a numerical procedure to simulate chloride ingression into cracked concrete with different crack geometry characteristics. Cracked concrete is divided into two parts, sound zone and cracked zone. For stress-free concrete, the diffusion coefficient of sound zone is approximately assumed to be the same as sound concrete, and the diffusion coefficient of cracked zone is expressed as a piecewise function of crack width. Two-dimensional finite element method is used to determine chloride concentration. It is found that, with the increasing of crack width, crack depth, and crack amount, chloride ingression will aggravate. The analysis results generally agree with experimental results.

show abstract

“…The chloride permeability coefficient of concrete was measured by the Nernst-Einstein-Lu (NEL) method [51,52] based on the Nernst-Einstein equation. After 28 days, a 100 mm × 100 mm × 400 mm concrete specimen was cut into three samples with a size of 100 mm × 100 mm × 50 mm, and the two test faces which needed to be in contact with the electrodes were polished.…”

Section: Chloride Permeability Testmentioning

confidence: 99%

Effects of Aggregate Micro Fines (AMF), Aluminum Sulfate and Polypropylene Fiber (PPF) on Properties of Machine-Made Sand Concrete

Wang

Wang³

2019

Applied Sciences

View full text Add to dashboard Cite

With the depletion and increasing demand of river sand, machine-made sand could be used more and more in concrete. In order to improve the properties of machine-made sand concrete, the effects of the aggregate micro fines (AMF) content, aluminum sulfate, and polypropylene fibers (PPF) on the slump, compressive strength, water permeability, and the chloride permeability coefficients were investigated through a single factor test method, and related mechanisms were analyzed. The results show that the optimum contents of AMF, aluminum sulfate, and the polypropylene fiber are 10 wt%, 1 wt%, and 0.6 kg/m3, respectively. The optimum content of AMF improved the compactness of concrete. The addition of aluminum sulfate promoted the initial formation of ettringite, and thereby improved the compressive strength and the permeability resistance. The polypropylene fiber can modify the pore structure distribution of concrete and reduce the porosity, thereby improving the impermeability of the concrete. The compressive strength of the machine-made sand concrete could be increased by more than 20%, and the water/chloride permeability coefficients could be decreased by more than 45%.

show abstract

Modeling of chloride diffusion in concrete containing low-calcium fly ash

Cited by 9 publications

References 16 publications

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

Simulation of Chloride Diffusion in Cracked Concrete with Different Crack Patterns

Effects of Aggregate Micro Fines (AMF), Aluminum Sulfate and Polypropylene Fiber (PPF) on Properties of Machine-Made Sand Concrete

Contact Info

Product

Resources

About