National Concrete Pavement Technology Center

Project description

The design strength of traditional concrete is obtained at 28 days. However, there is an increasing need to predict design strength at earlier ages. Often, projects cannot wait to verify in place concrete has reached the desired strength, particularly with increased use of acceleration construction schedules. Presently, Tennessee Department of Transportation (TDOT) accepts the design strength of traditional concrete at 28 days and still bases acceptance and payment on 28-day cylinder breaks. However, TDOT is administering more early strength requirements in plans due to accelerated project delivery timelines. Therefore, TDOT needs to set early age acceptance criteria that can be used to approve early strength concrete at the age that it is intended to be in service. TDOT has standard (Classes) of mixes, it would be possible to determine calibration curves over a range of mixes and apply this range to field placement. If done properly, it may be possible to eliminate most destructive field cylinder testing.