Title:
A Strength Definition for the Water to Cementitious Materials Ratio
Author(s):
A. Hassaballah and T. H. Wenzel
Publication:
Symposium Paper
Volume:
153
Issue:
Appears on pages(s):
417-438
Keywords:
concretes; fly ash; pozzolan cements; strength; water-cement ratio; Materials Research
DOI:
10.14359/1081
Date:
6/1/1995
Abstract:
The water-to-cementitious materials ratio (W/CM) is recognized as an important variable in understanding and controlling the quality of concretes containing pozzolan powder additives, such as fly ash. This paper presents part of a study to determine a correct way to evaluate the contribution of fly ash to concrete strength as is usually indicated by the W/CM ratio. A rational mathematical model of the form W/CM = W/(C + K * FA) is presented, in which W, C and FA are water, cement, and fly ash contents per m 3 of concrete, respectively. K is a pozzolan efficiency factor based on comparing the compressive strength of two concretes having the same workability and the same amount of cement. An experimental program was conducted to demonstrate the use of the proposed W/CM ratio model and corresponding K values. The variables studied were class and addition level of fly ash and slump, strength, and age of concrete. Results show that the model describes and considers the influence of fly ash on the rheological properties of fresh concrete and on the strength of hardened concrete. The model is also suitable for use as an equivalent to Abram's law to account for modern day powder additives.