Water permeability and chloride ion diffusion in portland cement mortars: Relationship to sand content and critical pore diameter

1995 ◽  
Vol 25 (4) ◽  
pp. 790-802 ◽  
Author(s):  
Pavla Halamickova ◽  
Rachel J. Detwiler ◽  
Dale P. Bentz ◽  
Edward J. Garboczi
2009 ◽  
Vol 79-82 ◽  
pp. 99-102 ◽  
Author(s):  
Zhu Ding ◽  
Feng Xing ◽  
Ming Zhang ◽  
Peng Liu

Penetration and diffusion of chloride ions in concrete can lead to the corrosion of steel bar and shorten the service life of concrete structures. Phosphoaluminate cement (PAC) is a new cementitious material which has many special properties compared to Portland cement (PC). In the study, chloride ion diffusion in PAC concrete was tested with RCM method. The phase composition and morphology of hydration products, pore volume of hardened paste cured for 28d were analyzed with X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP). The results show that chloride ion diffusion coefficient of PAC concrete is much lower than that of Portland cement concrete under the same test conditions. The hydration products of PAC are main micro-crystalline phase and gel of phosphate and/or phophoaluminate, which formed a dense microstructure. There is no calcium hydroxide produced in the PAC hydration system. In hardened PAC paste, chloride ions might replace the atom group [OH] - and [PO4]3- of hydrates and become stable compounds. The resistance to chloride ion diffusion of PAC concrete will increase with the hydration age, because its microstructure becomes denser with the hydration age increasing.


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

2011 ◽  
Vol 324 ◽  
pp. 340-343
Author(s):  
Abdelaziz Benmarce ◽  
Hocine Boudjehem ◽  
Robila Bendjhaiche

Abstract. Self compacting concrete (SCC) seem to be a very promising materials for construction thanks to their properties in a fresh state. Studying of the influence of the parameters of specific designed mixes to their mechanical, physical and chemical characteristics in a state hardened is an important stage so that it can be useful for new-to-the-field researchers and designers (worldwide) beginning studies and work involving self compacting concrete. The objective of this research is to study the durability of self compacting concrete. The durability of concrete depends very much on the porosity; the latter determines the intensity of interactions with aggressive agents. The pores inside of concrete facilitate the process of damage, which began generally on the surface. We are interested to measure the porosity of concrete on five SCC with different compositions (w/c, additives) and vibrated concrete to highlight the influence of the latter on the porosity, thereafter on the compressive strength and the transfer properties (oxygen permeability, chloride ion diffusion, capillary absorption).


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