Mortar Properties

Good mortar in a plastic state possesses good workability and the ability to retain water.

Good workability allows the mortar to spread smoothly, adhere to vertical surfaces without sagging, extrude from joints without falling, and position masonry units easily. Mortar workability is also gauged by its sliding behavior and adhesion to a trowel.

Water retention refers to avoiding the loss of water to the atmosphere or absorption by masonry units.

Mortar hardens and loses plasticity, resulting in tensile bond strength.

This strength is evaluated by joining bricks with mortar, curing them, and then separating the units using a tensile testing machine.

Bond strength is usually high on textured surfaces, whereas it is typically low on smooth surfaces.

Compressive strength is determined by testing cured 2 inch mortar cubes in a lab compression-testing machine to record the maximum load before failure.

In construction, mortar is characterized by: M, S, N, and O, which are defined depending on the compressive strength values after 28 days.