RD & QC Brick and Block
These are specialty fixtures used for testing full size formed concrete, clay, and rock materials. The fixtures are spherically seated compression platens sized for testing either bricks or concrete blocks. The platens provide a hardened surface (Rockwell HRC 58/60) for complex compression tests in which uniform stress distribution is critical.
The Block test fixtures are designed to accommodate one full concrete block. The platen for both the upper and lower surfaces is large enough to prevent any part of the specimen from overhanging the plate. This assures even loading across the entire specimen.
The Brick test compression fixtures are designed to accommodate either full size or half size specimens. This fixture is used to determine the compressive strength of the specimen when resting on the frame's lower plane platen (when provided).
The Brick test flexure fixture is designed to apply a three-point flexure load to a full size specimen to determine the Modulus of Rupture. It consists of two lower supports that can be adjusted to three different spans to accommodate different length specimens. The lower supports are free to pivot in the longitudinal and transversed directions to prevent exert any force on the specimen in these directions.
The upper loading surface is a flat loading nose that can pivot longitudinally with the specimen.
Additional spacers are typically required to achieve the correct test space opening.
Principe de fonctionnement
The high Rockwell Scale hardness of the compression platens ensures lack of deformity at pressures up to their capacity. Their inscribed concentric circles along with a crosshair axis ensure proper, centered placement of the specimen, thereby increasing the validity of test results. A level seating surface and even load distribution over the specimen is ensured due to the high tolerance in the flatness of the surface. This aids the operator in attaining valid test results and true failure measurements.
Both types of fixtures utilize a spherical seat that is designed to accommodate angular displacement (up to 4 degrees) of the top of the specimen with reference to the machine’s loading axis. This is accomplished through the spherical seating of the platen and the metal springs connecting the platen and the base. Spherically seated compression platens are typically mounted to the upper frame of RD or QC machines. They are normally used in conjunction with a plane compression platen that is mounted to the piston of the machine.
- Conform to ASTM C-67 and C-140, depending on the fixture
- All fixtures mount in Prism frames using a holding stem and set screw assembly
- Operate in static compression only