STATISTICAL DETERMINATION OF CEMENTITIOUS MATERIALS CONTENT IN HARDENED CONCRETE, PART II

摘要

This paper is a continuation of a paper entitled “Statistical Determination of CementitiousrnMaterials Content in Hardened Concrete” that was presented in the twenty second ICMA inrnMontreal, Canada. In that paper, a regression equation was developed based on paste contentsrndetermined by point count of twenty concrete samples with known mix proportions. Using thernregression equation, the cementitious materials content can be calculated once the paste contentrnis determined via traditional point count method, and the water-to-cementitious materials ratiorn(w/cm) is estimated. However, in pursuing a better mathematical fit to the data, the equationrnused a cross term which is the product of paste content and w/cm. Consequently, the resultingrnequation is a curve having a limit w/cm value. This would result in errors in the calculation of therncementitious materials content around the limit value.rnIn this paper, a new linear regression equation is developed based on the point count data ofrnthirty one concrete samples with known mix proportions. No limit value can be reached from thernequation. The new equation has a coefficient of determination (R2) of 0.96 and a standardrndeviation of 23, and is equally effective for portland cement concrete and concrete containing flyrnash. Total cementitious materials content can be readily calculated using the equation. Inrnaddition, the effect of fly ash, and the relationship between the cementitious materials contentrnand the paste volume determined by point count method are further discussed.