STATISTICAL OPTIMIZATION OF LOW SLUMP TERNARY CONCRETE MIXTURES WITH GROUND GRANULATED BLAST FURNACE SLAG (GGBS) AND HIGH CALCIUM FLY ASH FOR PAVEMENT APPLICATIONS

This paper presents the results of optimization study of ternary concrete mixtures for use in pavements. The variables used in the study included the total volume of paste in the mixture (21 to 25%) and the level of cement replacement by combination of fly ash (10-20%) and ground granulated blast furnace slag (GGBFS) (18-30%). A total of 16 different concretes (including one control, cement-only mixture) were produced in the laboratory and tested for various fresh properties, compressive and flexural strength, scaling resistance, free shrinkage, and rate of water absorption. The optimal mixtures were found to contain, respectively, 15% of fly ash, 26% of GGBFS, and 21.5% of paste. Moreover, it was found that the fly ash content was the most influential variable in the ternary systems studied and that it could only be varied in a relatively narrow range (from 10 to 15.5%) in optimal ternary mixes with fixed amount of paste.