mortaring

Mortaring is the process of binding masonry units, such as bricks, blocks, or stones, with mortar. It serves to fill joints, bond units together, distribute loads, and seal against moisture. The mortar hardens over time to form a single, stable masonry assembly.

Mortar mixes typically consist of a binder, an aggregate (sand), and water. Traditional lime mortars use lime as the binder with sand, while cement mortars rely on Portland cement. Modern mixtures may combine cement with lime or pozzolanic materials to improve workability, strength, and compatibility with existing masonry. The sand's grain size and cleanliness influence workability and bond, and additives or plasticizers can adjust open time and water retention.

Types of mortar are often defined by binder composition and strength. Cement mortars are commonly described by standards that designate different strengths (for example, higher-strength mixes for load-bearing work and lower-strength mixes for delicate restoration). Lime mortars, including hydraulic lime and pure lime putty mortars, are used where breathability and flexibility are important, such as in historic masonry. Cement-lime mortars blend the durability of cement with the compatibility of lime. The choice depends on the masonry units, climate, and performance requirements.

Techniques and workmanship involve proper mixing, proportioning, and placing of mortar. Typical joint widths vary by masonry type and unit size. Mortar should be worked into joints with a trowel, tooled to a finished profile, and protected during curing to prevent premature drying or freezing. In restoration, mortar compatibility and reversibility are important considerations.

Applications include brickwork, blockwork, and stone masonry. Mortaring also overlaps with pointing and repointing, which restore the mortar joints after installation. In historic buildings, lime mortars are often preferred for their permeability and resilience.