The current AASHTO maturity specification is designated T 325-04(2008) “Standard Method of Test for Estimating the Strength of Concrete in Transportation Construction by Maturity Tests."
This specification, as most, is built around ASTM C 1074 and is intended to be used for estimating the strength of concrete in pavements as well as structures. Specific uses are the timing of:
• Opening to traffic
• Form Removal
• Post Tensioning
• Termination of curing procedures
• Destructive methods of evaluating concrete strength
Absent in most other specifications, T 325 does recommend the minimum number of temperature/maturity sensors to be used on a concrete placement.
• Slabs, beams, and abutment walls: 5 per 100 cubic meters
• Small columns: 1
• Large columns: 2
• Pavements and overlays: 2 per 1000 sq meters
• Pavement repairs: 2 per 750 cu meters or one per repair
The AASHTO specification also addresses situations where not every lot of concrete is tested.
One interesting recommendation by SHRP researchers is the usage of the Arrhenius function as opposed to Nurse-Saul. I’ll skip the Arrhenius versus Nurse-Saul soapbox speech for now, but will say that if Arrhenius models are used one should perform a rigorous calibration procedure at multiple temperatures, and be sure that the mix and materials are extremely consistent. As with any maturity technique, validate the mix often and follow the recommendations of the engineer of record on each jobsite.
Copies of the specification are available for purchase at several sites online including:
http://global.ihs.com and http://www.techstreet.com