How to Test Mortar

Mortar helps bind concrete together. However, if the mortar is too weak, environmental pressures can cause the concrete to crack, which can weaken the foundation of buildings set on the concrete and cause structural damage. Engineers thus test mortar using sample cubes and a compression unit to determine the type of pressure it should be able to withhold.

Mortar cubes
Limewater-curing tank and limewater
Clean rag
Scale
Pen and paper
Compression-testing machine
Level
Rubbing block

Instructions

- 1
  Prepare the mortar cubes for testing. Remove them from their wrappings and put them in a saturated limewater-curing tank.
- 2
  Remove one cube from the tank and wipe it dry. Remove sand or other debris from the cube's surface as you wipe. Measure and record the cube's weight and volume.
- 3
  Place the cube in the compression testing machine. The bearing block should rest on top of the flat top of the cube and the cube should be centered in the machine. Check that the cube's receiving surface is level and sand this surface with a rubbing block to level it if it is not.
- 4
  Use the machine to apply a uniform load of pressure to the cube. The specifics of how to apply pressure depend on the cube's age, weight and volume. Continue applying the uniform rate until the cube cracks. Record the details of what you did to the cube and how the cube reacted.
- 5
  Repeat the process with the other cubes in the testing sample.

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