How to determine the consistency of wet-mixed masonry mortar?

The consistency of wet-mixed masonry mortar is typically determined using the flow or slump test, which measures the fluidity or workability of the mortar. Here’s how to conduct the test:

Equipment Needed:

1. Flow cone or slump cone
2. Tamping rod
3. Measuring tape
4. Stopwatch
5. Mortar sample

Procedure:

Flow Test:

1. Preparation: Ensure that the flow cone is clean and free from any obstructions. Place it on a flat, level surface.
2. Sample Preparation: Prepare a fresh sample of wet-mixed mortar according to the desired mix proportions and consistency requirements.
3. Filling the Cone: Fill the flow cone with the mortar sample in three layers, each approximately one-third of the cone’s height. Compact each layer using a tamping rod to remove any voids and ensure uniform filling.
4. Excess Removal: After filling the cone, strike off the excess mortar from the top of the cone using a straightedge or trowel.
5. Lifting the Cone: Carefully lift the flow cone vertically, ensuring no lateral movement, and observe the flow of mortar from the cone.
   • Measurement: Measure the distance traveled by the mortar flow from the bottom of the cone to the spread diameter using a measuring tape. Record this value as the flow diameter.

Slump Test:

1. Preparation: Ensure that the slump cone is clean and free from any debris. Place it on a flat, level surface.
2. Sample Preparation: Prepare a fresh sample of wet-mixed mortar according to the desired mix proportions and consistency requirements.
3. Filling the Cone: Fill the slump cone with the mortar sample in three layers, each approximately one-third of the cone’s height. Compact each layer using a tamping rod to remove any voids and ensure uniform filling.
4. Excess Removal: After filling the cone, strike off the excess mortar from the top of the cone using a straightedge or trowel.
5. Subsidence Measurement: Carefully lift the slump cone vertically in a smooth, steady motion, allowing the mortar to subside or slump.
   • Measurement: Measure the difference in height between the initial height of the mortar cone and the height of the slumped mortar. Record this value as the slump.

Interpretation:

• Flow Test: A greater flow diameter indicates higher fluidity or workability of the mortar, while a smaller flow diameter indicates lower fluidity.
• Slump Test: A greater slump value indicates higher workability or consistency of the mortar, while a smaller slump value indicates lower workability.

Note:

• The desired consistency of masonry mortar depends on the specific requirements of the application, such as the type of masonry units, construction method, and environmental conditions. Adjust the mix proportions and water content accordingly to achieve the desired consistency.