cementkalk

Cementkalk, or cement-kalk mortar, is a building material used for masonry and plastering that combines Portland cement with lime and sand. The lime content may be lime putty, hydrated lime or hydraulic lime, and the sand provides bulk. The lime component contributes workability, elasticity and vapour permeability, while the cement supplies early strength and durability. Together they aim to deliver a mortar that is strong enough for weather resistance yet breathable enough for historic or damp substrates.

Variants and applications: Cementkalk mortars are commonly used in the repair of historic masonry, exterior renders and interior plasters where some cement content is desired but full cement mortars would be too rigid or non-breathable. The exact mix depends on the application, climate and substrate, with the objective of balancing workability, bonding strength, durability and vapour diffusion. They are often preferred in conservation work because they can be tailored to match the properties of traditional lime mortars while providing improved early strength.

Properties and considerations: Compared with pure cement mortars, cementkalk mortars are generally more permeable and more forgiving on hygroscopic substrates, reducing moisture buildup and cracking when used appropriately. However, excessive cement content or improper curing can reduce porosity and trap moisture, so mixes should be chosen to suit the substrate and dampness conditions. Proper mixing, application thickness and curing conditions are important for long-term performance.

See also: lime mortar, cement mortar, render.