Title: Shortcomings of Current Compression Strength Tests for HSC and a Proposed Solution

Author(s): I. Luker and S.W. Tabsh

Publication: Symposium Paper

Volume: 228

Issue:

Appears on pages(s): 545-556

Keywords: compressive strength; concrete; modeling; precision; strain; stress; testing

DOI: 10.14359/14491

Date: 6/1/2005

Abstract:
This study discusses the possible ways in which the characteristics of a testing machine can influence the strength of a HSC specimen. Particular attention is given to the platen rotation, which is caused fundamentally by the eccentricity of the reaction force from the specimen, and results in non-uniform straining over the loaded area of the specimen. The strain gradient is measured by a parameter denoted “strain-ratio,” while the apparent strength is expressed by a parameter referred to “strength efficiency.” An empirical method for establishing the relationship between strength efficiency and strain ratio is described. This is done using batches of similar HSC specimens deliberately subjected to different degrees of non-uniform straining and compared to predictions using simple theory. It is found that the test results confirm the validity of the theoretical assumptions. Strain measurement between the loading platens during a regular compression strength test is suggested as a practical proposition due to its economic benefit.