Steel Retainer Rings for Unbonded Concrete Cylinder Capping

Steel Retainer Rings for Unbonded Concrete Cylinder Capping – ASTM C1231

Steel Retainer Rings are designed for use with neoprene capping pads during compression testing of concrete cylinders. The precision-machined steel retainers hold the elastomeric pad securely in position over each end of the specimen, creating an unbonded capping system that helps distribute the applied load across the cylinder end during testing.

Used in accordance with ASTM C1231, unbonded capping systems provide a convenient alternative to traditional sulfur mortar capping for qualifying concrete specimens. Retainers are used in pairs—one at the top and one at the bottom of the concrete cylinder—with appropriately selected neoprene pads installed inside each retainer.

Key Features

• Precision-machined steel alloy construction
• Holds neoprene capping pads securely during compression testing
• Designed for unbonded capping of concrete cylinders
• Used in accordance with ASTM C1231
• Helps distribute compressive load across the specimen end
• Eliminates the preparation and handling associated with sulfur mortar capping when unbonded caps are permitted
• Sold as a pair for the top and bottom of the test cylinder
• Neoprene pads are available separately in multiple durometers
• Available for common concrete cylinder diameters