Types of mortars and their historic uses

[edit] Most common types of mortars

The most common types of mortars include:

• Lime mortars
• Natural cement mortars
• Earth mortars
• Portland cement mortars
• Portland cement and lime mortars

If considering using these materials in a construction project, it's crucial to understand the historical contexts in which they have previously been utilised. From ancient lime mortars to the advent of modern cements, each type reflects a unique chapter in the evolution of construction practices. Here is a look at the different types and historical uses of cement and lime mortars.

[edit] Lime mortars

Lime mortars have a long history, dating back thousands of years, and remain vital in the repair and conservation of traditionally build structures. Throughout British architectural history, lime mortars were commonly used in structures made of stone, brick, or earth. At Cornish Lime, we stock a range of lime mortars.

Whilst remaining in common use in the construction of buildings, the reality is the composition of these mortars varied depending on the era and location. In the pre-1800s and early 1800s, quicklime mortars were prevalent. These mortars involved mixing quicklime with coarse sand and water to create a slaked lime mixture. Analysis by the Scottish Lime Centre found that about four-fifths of mortars from this period followed this method.

With advancements in kiln technology and industrial transport during the 1800s, the usage of natural hydraulic lime (NHL) mortars surged. Predominantly sourced from regions like the Blue Lias belt, these NHL mortars present identification challenges, often requiring mortar analysis for definitive determination.

For those fascinated by historical structures, our article on the Historic Use of Lime in 10 Traditional Buildings & Landmarks offers further insights.

[edit] Natural cement mortars

Natural cements, patented by James Parker in 1796, experienced significant adoption across the United Kingdom in the following century as new source rocks meeting mineralogical requirements were discovered.

These cements, known for their binder-rich composition and distinctive colouration, often resembling red or orange iron oxide hues, offered a contrast to lime mortars, which derive their colour primarily from the sand used.

Notable examples of natural cement applications can be found in London, where both mortars and renders can still be found on prominent buildings even now. Over time, aged natural cement renders may develop hydraulic cracking, reminiscent of the shrinkage patterns seen in arid riverbeds.

[edit] Portland cement mortars

In addition to natural and earth mortars, the history of Portland Cement also merits attention. Developed in the 19th century, Portland cement revolutionised construction practices becoming the first widespread artificially created binder.

Named after the creamy colour of Portland stone, this material is now understood to likely have been similar in strength to one of the stronger modern NHL5 limes. When looking at the chemistry of these materials, it can be easy to confuse a strong hydraulic lime mortar with an early Portland cement.

[edit] Earth mortars

Conversely, earth mortars, fashioned from locally sourced subsoil materials, represent a traditional yet pragmatic alternative. While prevalent in locales with limited access to lime, earth mortars may incorporate the addition of quicklime, evident through the presence of soft, white, powdery lime inclusions.

Typically, the incorporation rate of lime in earth mortars is lower compared to its usage in sand and lime mortars.

--Adam Brown of Cornish Lime

[edit] Related articles on Designing Buildings

• Binding agent.
• Cement mortar.
• Defects in brickwork.
• Defects in stonework.
• Dry hydrate lime mortar.
• Grout.
• Gypsum.
• Harl.
• Hemp lime construction: A guide to building with hemp lime composites.
• High alumina cement.
• High lime low alkali glass.
• Hot-mixed lime mortar.
• Hot-mixed mortars: the new lime revival.
• Hydraulic lime.
• Hydrated lime.
• Lime concrete.
• Lime mortar.
• Lime plaster.
• Lime putty mortar.
• Lime run-off.
• Mortar.
• Mortar analysis for specifiers.
• Non hydraulic lime.
• Pointing.
• Portland cement.
• Rendering.
• Soda-lime glass.
• Stucco.
• Types of mortar.
• The use of lime mortar in building conservation.
• Types of mortar.