A Study on the pH Value Changes of Blended Cement Paste According to the Carbonation

Life span of structures made with concrete was shortened by carbonation. This phenomenon makes pH in concrete lower. If pH value in concrete become below 10, rebar in concrete begin to be corroded. This pH value was effected by quantity of Ca(OH)2 that depends on cement types, hydration reaction and carbonation time. In this study, pH value and quantity of Ca(OH)2 in mortar which has blast furnace slag were tested according to hydration and carbonation time. As a test result, the more cement has blast furnace slag (BFS) and the longer carbonation time last, the lower pH value in mortar has. And using this quantitative analysis result of pH and Ca(OH)2, it may be used effectively when service life considering carbonation is predicted using FEMA.

References

[1] Yosihiro Masude et, Mathematical model on progress of carbonation of concrete, Concrete Research and Technology, Japan Concrete Institute, p.125∼133, Vol. 2, No. 1, (1991).

[2] Vagelis.G. Papadakis et. Experimental investigation and mathematical modeling of the concrete carbonation problem, Chemical Engineering Science, Vol. 46, No. 5/6, pp.1333-1338, (1991).

DOI: https://doi.org/10.1016/0009-2509(91)85060-b

[3] Song,H. S et. Relation between rebar corrosion and concrete carbonation that has blast furnace slag, Korea Concrete Institute, proceeding, Vol. 13, pp.1193-1198, (2001).

[4] Lee,J. G et, Prediction model of service life for concrete using measurement carbonation, Korea Concrete Institute, Vol. 15, No. 4, pp.529-540, (2003).

[5] Cheng-Feng Chang et, The experimental investigation of concrete carbonation depth, Cement and Concrete Research, vol. 36, pp.1760-1767, (2006).

DOI: https://doi.org/10.1016/j.cemconres.2004.07.025