Why Measure Molds?
Out-of-specification molds may cause density correlation problems that typically manifest themselves as high air void content. High air void content may cause one to question gyratory compactor calibration and/or the mix design potentially costing one time and money. Annex A of AASHTO T312 describes the equipment and procedures required to properly measure molds.
Pine Test Equipment, Inc. offers a Mitutoyo 3-point bore gage and a master ring to measure internal mold diameter. Pine field service technicians use this equipment to check molds as part of service package for a gyratory compactor. Pine can also certify molds at the factory.
This equipment performs according to AASHTO T312 Annex A.
The AFGM01 Bore Gage utilizes a three point contact system in conjunction with a digital micrometer head. Use the AFGM03 150 mm Master Ring to preset the gage to 150 mm, retract the contact probes, insert the gage into the mold, turn the micrometer knob until the knob clicks, then read the diameter directly on the digital readout. The AFGM01 includes an extension to provide an easy reach to the base of SGC molds and can be set to read in either millimeter or inch units.
The AFGM03 150 mm Master Ring serves as the NIST-traceable verification/calibration standard for the AFGM01 Bore Gage. The Master Ring has a 3-year certificate and comes with spacers to help obtain repeatable positioning of the gage inside the mold bore as required by Annex A.