AASHTO T 325:04(2020) Standard Method of Test for Estimating the Strength of Concrete in Transportation Construction by Maturity Tests.
AASHTO T 325 can he used to estimate the strength of concrete placed in pavements and structures. These estimates provide guidance useful in making decisions concerning opening to traffic, form removal, post tensioning, termination of curing procedures. and initiation of strength tests on the in-place concrete, such as coring and pullout tests.
4.2. The most critical limitations of the procedures presented are (I) batching or placement errors that are not detected, (2) curing errors other than those that affect temperature that are not detected, and (3) the actual strength of the concrete that is not measured.
Note 1—Concrete must he cured in a condition that supports cement hydration/pozzolanic reactions.
4.3. This standard provides technical personnel with a coordinated procedure for (1) developing a strength—maturity relationship for the approved concrete job mix in the laboratory. (2) determining the temperature history of the in-place concrete, (3) determining the maturity index of the in-place concrete, and (4) using the strength—maturity relationship and the maturity index to estimate the strength of the in-place concrete.
Labora tori Recj uireinenls:
Personal safety equipment required by the laboratory or OS HA, or both, for work in the laboratory concrete mixing and testing areas.
5.1 .2. Temperature sensors suitable for embedment in the center of cylindrical concrete test specimens and a device suitable for monitoring and recording the temperature.
5.1 .3. A computer terminal for input of laboratory test data or a supply of concrete test reports.
5.2. Field Requirements:
5.2.1. Personal safety equipment required by the laboratory/field organization or OSHA, or both, for work in the field concrete placement areas.
5.2.2. Temperature probes/sensors suitable for embedment in the concrete placement.
5.2.3. A device Suitable for monitoring and recording the temperature of the concrete. The device may be a system with a computer remote from the job site that reads and logs the probes/sensors.AASHTO T 325 pdf download.