Lime mortar lime putty when mixed at a 1 to 3 ratio, fill these voids to create a compact mortar. Analysis of mortar samples from historic buildings typically indicates a higher ratio of around 1 part lime to 2 part aggregate/sand was commonly used. A traditional coarse plaster mix also had horse hair added for reinforcing and control of shrinkage, important when plastering to wooden laths and for base (or dubbing) coats onto uneven surfaces such as stone walls where the mortar is often applied in thicker coats to compensate for the irregular surface levels. If shrinkage and cracking of the lime
Structural material walls become unstable at relatively small heights. High masonry structures require stabilisation against lateral loads from buttresses (as with the flying buttresses seen in many European medieval churches) or from windposts. Historically masonry was constructed with no mortar or with lime mortar. In modern times cement based mortars are used. The mortar glues the blocks together, and also smooths out the interface between the blocks, avoiding localised point loads that might have led to cracking. Since the widespread use of concrete, stone is rarely used as a primary structural material, often only appearing as a cladding, because of its cost