Browse > Article
http://dx.doi.org/10.11112/jksmi.2014.18.1.111

Leaching Capacity and Rate of Alkali Ions from Hardened Cement Paste  

Shim, Hyun-Bo (한국콘크리트학회)
Hwang, Jun-Pil (한양대학교)
Ann, Ki-Yong (한양대학교)
Publication Information
Journal of the Korea institute for structural maintenance and inspection / v.18, no.1, 2014 , pp. 111-118 More about this Journal
Abstract
The present study concerns the leachability of alkali ions from hardened cement paste in terms of an increase in the pH together with the rate of alkali leaching. To evaluate the influence of mix design on the leaching capacity and rate of alkali, different water-cement ratios (W/C) and binders were used to manufacture paste specimens. The cement paste was made in the form of rectangular bucket where deionised water was subsequently supplied as solvent media. Then the specimen was wrapped in polythene film to avoid contact to atmospheric conditions, which may affect the water chemistry in the bucket. The pH of media was monitored until no further change in the pH value was observed, of which value then used to calculate the leaching capacity and rate. The influence of binder on the pH of solvent is more dominant than that of water to cement ratio: OPC paste produced the highest level of alkali leaching, whilst 30% PFA and 60% GGBS pastes imposed lower level of alkali leaching. After the monitoring of the pH, the inner bucket was ground with an increment of 1.0 mm to measure the leaching influence using the suspension consisting of paste powder and deionised water. It was found that the impact zone for OPC was about 7-8 mm, whilst 30% PFA and 60% GGBS had deeper impact depth of the alkali leaching.
Keywords
Leaching; Alkalinity; Hydroxide ions; Calcium hydroxide; Calcium silicate hydroxide; pH;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Adenot, F., and Buil, M. (1992), Modelling of the corrosion of the cement paste by deionized water, Cement and Concrete Research, 22, 489-496.   DOI
2 Despand, L. M., Clark, M. W., Aragno, M., and Vancov, T. (2010), Minimising alkalinity and pH spikes from Portland cement-bound bauxsol (seawater-neutralized red mud) pellets for pH circum-neutral waters, Environmental Science Technology, 44, 2119-2125.   DOI
3 Duchesne, J., and Reardon, E. J. (1995), Measurement and prediction of portlandite solubility in alkali solutions, Cement and Concrete Research, 25, 1043-1053.   DOI
4 Eglinton, M. S. (1987), Concrete and its chemical behavior, Telford, London.
5 Faucon, P., Adenot, F., Jacquinot, J. F., Petit, J. C., Cabrillac, R., and Jorda, M. (1998), Long-term behavior of cement pastes used for nuclear waste disposal: review of physicchemical mechanisms of water degradation, Cement and Concrete Research, 28, 847-857.   DOI
6 Geankoplis, C. (2003), Transport processes and deparation process principles, Prentice Hall, Upper Saddle River, New Jersey.
7 Glasser, F. P., and Atkins, M. (1994), Cements in radioactive waste disposal, Materials Research Society Bulletin, 12, 33-39.
8 Hong, S. Y., and Rahman, A. A. (1999), Alkali binding in cement pastes Part I. The C-S-H phase, Cement and Concrete Research, 29, 1893-1903.   DOI
9 Kamali, S., Moranville, M., and Leclerco, S. (2008), Materials and environmental parameter effects on the leaching of cement pastes: experiments and modeling, Cement and Concrete Research, 38, 575-585.   DOI
10 Lloyd, R. R., Provis, J. L., and van Deventer, J. S. J. (2010), Pore solution composition and alkali diffusion in inorganic polymer cement, Cement and Concrete Research, 40, 1386-1392.   DOI
11 Lovera, P., Adenot, F., Jorda, M., and Cabrillac, R. (1997), Physico-chemical transformation of sulfated compounds during the leaching of highly sulfated cemented wastes, Cement and Concrete Research, 57, 1523-1532.
12 Mehta, P. K. (2004), Concrete: microstructure, properties and materials (3rd edition), Mc Graw Hill, New York.
13 Saeki, T., and Monteiro, P. J. M. (2005), A model to predict the amount of calcium hydroxide in concrete containing mineral admixtures, Cement and Concrete Research, 35, 1914-1921.   DOI   ScienceOn
14 Schiopu, N., Tiruta-Barna L., Jayr, E., Mehu J., and Moszkowicz, P. (2009), Modelling and simulation of concrete leaching under outdoor exposure conditions, Science of the Total Environment, 11(27), 1613-1630.
15 Taylor, H. F. W. (1990), Cement Chemistry, Academic Press, London.