Title: Statistical Measures of HPC Compressive Strength

Author(s): S.F. Freyne, W.M. Hale, and B.W. Russell

Publication: Symposium Paper

Volume: 229

Issue:

Appears on pages(s): 335-348

Keywords: compressive strength; high performance concrete (HPC); normality; repeatability

DOI: 10.14359/14746

Date: 9/1/2005

Abstract:
Six HPC mixtures were batched multiple times to assess the batch-to-batch repeatability and also the normality of the compressive strength results. The HPC mixtures had compressive strength values at 28 days between 61.0 to 94.3 MPa. The coefficient of variation (CV) is a useful measure of the batch-to-batch repeatability; a low CV is indicative of a high level of repeatability. At 28 days, the CV ranged from 2.10% to 8.30%. The repeatability of four of the mixtures was considered “excellent” or “very good” according to the ACI 363 standards, while the repeatability of the remaining two mixtures was considered “poor.” With five of the six mixtures, the CV was lower at 28 days than at 1 day. One of the issues most likely to have contributed to the CV of the compressive strength results was the innacuracy of determining the aggregate moisture contents. The HPC compressive strength results generally followed a normal distribution. However, some irregularity was observed in the relative frequency histograms.