Mesoscopic chloride ion diffusion model of marine concrete subjected to freeze-thaw cycles

2016 ◽  
Vol 125 ◽  
pp. 337-351 ◽  
Author(s):  
Ben Li ◽  
Jize Mao ◽  
Toyoharu Nawa ◽  
Zongmin Liu
2011 ◽  
Vol 368-373 ◽  
pp. 361-364 ◽  
Author(s):  
Feng Qu ◽  
Di Tao Niu

Under action of repeated freeze-thaw cycles, different changes of pore structure features has occurred in different varieties of concrete.In this study, the average pore size of concrete and total porosity was discussed especially with the trends.Based on this, the gas diffusion model and the chloride ion diffusion model in concrete was also discussed with the pore structure,which indicated that the freeze-thaw damage of concrete pore structure will have a greater impact to the durability of concrete, and so the life of concrete structures would be affected.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5675
Author(s):  
Changhyuck Lim ◽  
Gyuyong Kim ◽  
Gyeongtae Kim ◽  
Bokyeong Lee ◽  
Youngduck Kim ◽  
...  

Wave power marine concrete structures generate electrical energy using waves. They are exposed to a multi-deterioration environment because of air and hydrostatic pressure and chloride attack. In this study, the effect of air pressure repeatedly generated by water level change of wave power marine concrete structures on the chloride-ion diffusion of marine concrete was analyzed. The chloride-ion diffusion of wave power marine concrete structures was evaluated. The results show that the air chamber and bypass room, which were subjected to repetitive air pressures caused by water level changes, showed a higher water-soluble chloride-ion content compared to the generator room and docking facility, which were subjected to atmospheric pressure. Field exposure tests and indoor chloride attack tests were performed using fabricated specimens to analyze the effect of pressure on chloride-ion penetration. It was confirmed that Portland blast furnace slag had a greater inhibitory effect on chloride-ion penetration than ordinary Portland cement. The concrete specimens subjected to pressure showed increased capillary pores and micro-cracks. We devised an equation for calculating the diffusion coefficient based on measured data and estimating the diffusion coefficient for the location receiving repeated air pressure by using the diffusion coefficient of the location receiving general atmospheric pressure.


2011 ◽  
Vol 689 ◽  
pp. 336-342 ◽  
Author(s):  
Wei Bo Huang ◽  
Xu Dong Liu ◽  
Ping Lu ◽  
Jing Zhang

The deterioration of coated concrete subjected to co-action of freeze-thaw cycles-NaCl solution immersion double factors exposure was investigated in this study. Adhesion, chloride content and resistance of chloride ion diffusivity of two types of polyaspartic ester polyurea coated concrete were analyzed. Test results showed that the adhesion of QF-1 (PAE-b-H12MDI prepolymer H66) and QF-2 (PAE-b-H12MDI prepolymer H62) coated concrete reduced about 5% respectively which kept excellent under the double factors exposure after 200, 300 days and 25, 50 times of cycles. The degradation process of coated concrete simultaneously exposed to co-action exposure was significantly accelerated. In co-action exposure tests, the average chloride ion content of coated concrete increased about 33% and 87% after 25 and 50 times of cycles compared with single NaCl solution immersion exposure; the chloride ion diffusion coefficient of concrete substrate increased with the increase of exposure time and freeze-thaw cycles. Freeze-thaw cycles results showed a severe influence on chloride ion diffusion and permeation of surface protection coating of concrete. Research also showed that the chloride ion diffusion of coated concrete subjected to the co-action of freeze-thaw cycles-NaCl solution was coincided with the Fick’s second law.


2013 ◽  
Vol 671-674 ◽  
pp. 1652-1656 ◽  
Author(s):  
Feng Qu ◽  
Di Tao Niu

With repeated action of freeze-thaw cycles, chloride ion diffusion characteristics changed obviously in concrete structure. In the study, the chloride ion diffusion coefficient and the surface chloride ion concentration were discussed especially with the trends. Based on these facts, the chloride diffusion model and the improved model of concrete was also discussed based on its time-dependent characteristics, which indicated that the freeze-thaw damage of concrete would have a greater impact to the chloride transport course in the concrete, and so on the service life of concrete structures would be affected.


2012 ◽  
Vol 14 (1) ◽  
pp. 332-335
Author(s):  
Ditao Niu ◽  
Chengfang Yuan ◽  
Da Ming Luo

2018 ◽  
Vol 23 (1) ◽  
pp. 287-294 ◽  
Author(s):  
Tao Yang ◽  
Bowen Guan ◽  
Guoqiang Liu ◽  
Yanshun Jia

2015 ◽  
Vol 77 (32) ◽  
Author(s):  
Nurazuwa Md Noor ◽  
H. Hamada ◽  
Y. Sagawa ◽  
D. Yamamoto

This paper present the effect of crumb rubber on its ability to produce concrete with structural strength when it was used directly from the plant without any treatment process. Crumb rubber was added as fine aggregates at 0%, 10%, 15% and 20% of sand volume meanwhile silica fume was added at 10% by cement weight. Three main series of concrete namely rubberized concrete with water-to-cement ratio of 50% and 35% was design and development of compressive strength was observed from day 7 until 91 days. Also, effectiveness of crumb rubber under flexural strength and splitting tensile strength was studied at 28 days curing age. Effect of crumb rubber on durability performance was done on chloride ion penetration resistance performance by migration test and by immersion in salt water. Chloride ion diffusion in rubberized concrete by migration test was carried out under steady state condition using effective diffusion coefficient, De meanwhile, immersion test in salt water was conducted under non-steady state condition using apparent diffusion coefficient, Da. Results showed that compressive strength was decrease with the increasing of crumb rubber in the mixture.  Even though the strength were reducing with the inclusion of crumb rubber, the reduction were less than 50% and it achieved acceptable structural strength. Chloride transport characteristics were improved by increasing amount of CR and rubberized concrete with w/c = 0.35 gave better resistance against chloride ion compared to w/c = 0.50 with more than 50% difference. Silica fume provide slightly strength increment compared to normal rubberized concrete and the same behavior was observed during chloride ion diffusion test.


2001 ◽  
Vol 46 (2) ◽  
pp. 109-120
Author(s):  
L.S. Selwyn ◽  
W.R. Mckinnon ◽  
V. Argyropoulos

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