Executive vice president, National Ready Mixed Concrete Association and National Aggregates Association, Silver Spring, MD
ASTM cement specifications rely on tests of the cement in standard mortars to control the strength-producing and air-entraining characteristics of the cement. The compressive strength of mortar is used by cement manufacturers to monitor the quality of their products. Concrete producers also use these mortar strengths to estimate the probable effect of the cement on concrete strength, especially when concrete strengths are lower than expected. However, cement manufacturers are reluctant to assume that these strengths bear any formal relationship to strength performance in concrete. Over the past 40 years, several researchers have studied the degree to which the results of the standard mortar tests correlate with cement performance in concrete. This paper reviews some of these studies and compares them to extensive data developed in the reference sample programs of the ASTM Cement and Concrete Reference Laboratory.
The standard ASTM compressive strength and air content methods used to test cement are found to correlate quite well with cement performance in concrete if steps are taken to avoid the variability associated with reliance on tests of single batches.
Paper ID: CCA10600J