Title: Efficiency Factors (k-Values) for Supplementary Cementing Materials Regarding Carbonation and Chloride Penetration

Author(s): V. G. Papadakis

Publication: Symposium Paper

Volume: 192

Issue:

Appears on pages(s): 173-188

Keywords: carbonation; cholrides; fly ash; mortar; silica fume

DOI: 10.14359/5748

Date: 4/1/2000

Abstract:
For comparing the relative performance of supplementary cementing materials (SCM) with regard to concrete durability, the concept of efficiency factor may be used. The efficiency factor (k-value) is defined as the part of the SCM in an SCM-concrete which can be considered as equivalent to portland cement. In this work, three typical SCM were studied: a silica fume, a low-calcium fly ash and a high-calcium fly ash. Accelerated carbonation and chloride penetration tests were performed. With regard to 28-day compressive strengths, penetration test were performed. With regard to 28-day compressive strengths, k-values of 3, .5, and 1 for silica fume, low-calcium fly ash, and high-calcium fly ash, respectively, were estimated. Mathematical models describing the carbonation propagation and chloride intrusion were applied to estimate the durability k-values. Higher k-values with respect to chloride penetration were found, indicating that SCM reduce the chloride permeability more effectively than they improve the compressive strength. On the contrary, with respect to carbonation depth, k-values of .3, .5, and .7 for silica fume, low-calcium fly ash and high-calcium fly ash, respectively, were estimated. A theoretical explanation of these results is also given.