Overview
This lecture explains the proper procedure for filling, consolidating, and finishing concrete cylinder molds for testing.
Cylinder Mould Types & Filling
- Use either 4x8-inch or 6x12-inch cylinder molds for concrete samples.
- Fill 4x8-inch molds in two equal lifts by volume.
- Fill 6x12-inch molds in three equal lifts by volume.
Consolidation Process
- After each lift, rod the concrete 25 times using a 3/8-inch diameter rod.
- Rodding should penetrate the lift below to ensure good consolidation.
- You may also consolidate using your open hand or a mallet.
Finishing & Protection
- After the final lift, strike off the top using the rod, a handheld float, or a trowel.
- Clean off excess concrete from the mold surface.
- Protect the finished sample from evaporation by sealing with a plastic lid if available.
- Clearly mark the cylinder for identification.
Transport & Storage
- Transport the sealed and marked cylinder to the location for initial curing.
Key Terms & Definitions
- Lift — A single layer of concrete placed in the mold before consolidation.
- Rodding — Inserting a rod repeatedly into concrete to remove air pockets and consolidate.
- Strike Off — Leveling the top surface of the mold to be flush with the rim.
Action Items / Next Steps
- Practice filling and rodding cylinder molds as described.
- Ensure all samples are properly labeled and protected during initial curing.