Title: ACCEPTABLE VIBRATIONS ON GREEN CONCRETE

Author(s): Seamus F. Freyne, Mitchell L. Watkins, and Adam Browne

Publication: Materials Journal

Volume: 112

Issue: 3

Appears on pages(s): 471-476

Keywords: coarse aggregate; compressive strength; early age; foundation; green concrete; vibration.

DOI: 10.14359/51687393

Date: 5/1/2012

Abstract:
Vibrations are potentially harmful to green concrete in shaft foundations, and many states, including Mississippi, cautiously established limits in terms of compressive strength, distance boundary, and wait time to protect early-age concrete. These limits, however, could be overly conservative with respect to experimental evidence, and perhaps unnecessarily impede construction schedules and add to project cost. The objective of this study was to quantify the effects of early-age vibrations on concrete performance. Concrete cylinders were exposed to several combinations of vibration magnitudes and durations that were representative of shaft construction, and at ages coincident with the sensitive period between initial and final set. The vibrations had no consistent influence on compressive strength and electrical resistivity. There was also no discernable difference between limestone and river gravel coarse aggregates.