Title: Variables in Concrete Aggregates and Portland Cement Paste which Influence the Strength of Concrete
Author(s): William A. Cordon and H. Aldridge Gillespie
Publication: Journal Proceedings
Appears on pages(s): 1029-1052
Many researches and periodic articles during the past 40 years have not clearly established the validity of the relationship of water-cement ratio to strength presented by Abrams. Interest in this subject was revived by recent articles by Walker and Bloem, and Gilkey summarized current thinking on the subject in 1961. This study was undertaken not only to verify the findings of recent researchers, but to find explanations for the confusing, overlapping, and often opposing variables. Sixty-nine concrete mixes made with wide variations in water-cement ratio and maximum size of aggregate are reported. Strength theory postulations based on an analysis of Mohr’s circles for concrete are advanced. An adaptation of a 300,000 lb universal testing machine for triaxial testing of concrete is explained along with the result obtained with this equipment. It is possible to offer a reasonable explanation for conflicting test results and theory by analyzing the cohesion and angle of friction as related to combinations of paste failure, bond failure, and aggregate failure in concrete specimens.