Title:
Fly Ash Reduces Harmful Chloride Ions in Concrete
Author(s):
M. N. Haque, O. A. KayyaliI, and M. K. Gopalan
Publication:
Materials Journal
Volume:
89
Issue:
3
Appears on pages(s):
238-241
Keywords:
chlorides; concretes; fly ash; mixing; strength; superplasticizer; Materials Research
DOI:
10.14359/2565
Date:
5/1/1992
Abstract:
Concretes of high, low, and medium strength, with and without a fly ash and with and without a proprietary superplasticizer, were designed. The 75 x 150-mm concrete cylinders were cast and immersed in a sodium chloride salt solution of 19,350 ppm concentration. After 91 days of storage, the compressive strength of the concretes was determined and the chloride ions concentration in the specimens was evaluated by potentiometry. A decanted solution was used for the determination of the free chloride ions in the concrete specimens. The results suggest that adding fly ash to a plain concrete can significantly reduce the concentration of free chloride ions. A further addition of a superplasticizer in the fly ash concretes marginally enhanced the concentration of Cl- ions. An addition of the superplasticizer in the plain concretes also reduced the free chloride ions. Overall results suggest that a judicious use of fly ash in concrete making can decrease the incidence of chloride-induced corrosion of the reinforcement in concrete structures.