What Is Soft Stone Masonry Mortar?
Mortar is the "glue" that holds your masonry project together, binding building blocks and filling joints. It is available in a variety of hues and has specific characteristics to meet the needs of your build.
A mortar that has a high bond strength will help withstand the elements and provide a long-lasting finish. Extent of bond is another important attribute to consider.
Type N Mortar
When it comes to masonry, the mortar is just as important as the stone itself. It can make or break the integrity of your project. In a nutshell, a high quality mortar should have the right compressive strength, flexibility, bonding properties and moisture resistance.
For soft stone masonry, we typically use a light bodied mortar such as type N. This mortar has a medium compressive strength (minimum 1800 psi) and is mixed with one part Portland cement, one part lime and six parts of sand. This mix is good for exterior above grade walls, tuck pointing and other general masonry applications. It is also compatible with most types of ashlar masonry. For ashlar masonry where the faces of the stones are not dressed but rough tooled and chamfered, we recommend a higher strength mortar such as type S. This mortar can withstand more extreme gravity and lateral loads as well as below grade projects like masonry foundations and sewers.
Type S Mortar
The right mortar should have a combination of properties that align with the project requirements. It should be durable, help resist moisture and be easy to work with. It should also have the right compressive strength.
If a masonry project is on an exterior above grade and exposed to severe weather and high heat, a higher strength mortar like type S may be used. This mix is a good choice for tuck pointing brick or stone walls and can withstand soil pressure, wind, seismic loads and freeze thaw.
This mortar mix is typically made of one part Portland cement, one part lime and six parts sand and has a medium compressive strength. It can withstand heavy traffic and is great for tuck pointing brick and stone walls as well as new construction or repairs. This mortar is also great for lathing and plastering. It will bond with a wide variety of underlying materials and is ideal for masonry foundations, manholes and retaining walls.
Compressive Strength
All materials have a certain amount of compressive strength, the force which tries to squash them together. Understanding this allows builders, masons and masonry professionals to design structures with a strong enough material to resist the forces which will impact them.
Coursed ashlar is the least expensive class of stonework, and is laid in regular courses with continuous joints. The exposed faces are rough tooled and chamfered.
Patent-hammered work is the most expensive, and the finished stone has a fine appearance. This type of finish is often used on granite and hard limestone.
Mortar is the glue that holds masonry units together, binding brick and stone veneers, filling joints, and providing structural support. This workable paste consists of varying amounts of hydrated lime, Portland cement and sand combined to create a mix that meets specific requirements. Mortar mixes are classified according to their bonding properties, flexibility and compressive strength. These factors allow the mortar to withstand lateral loads, contract in response to changes in temperature and maintain its structural integrity.
Extent of Bond
The degree to which mortar bonds with stone is crucial. If masonry is not well bonded, moisture and movement can easily cause cracking. The right mix of mortar can flex and absorb these forces, protecting the structural integrity of the project.
In rubble masonry, the stones are undressed or comparatively roughly dressed, with wide joints since the stones are of irregular sizes. A good rubble wall, as illustrated in Fig. 19, should show headers, or blocks of larger size, about every four or five feet with long stretchers between them.
The finish shown at a, called scale work, is a pleasing and novel method of dressing stone, which can only be applied to softer stones, such as limestone. The drafts of each stone are cut in rows of shallow flutings, giving a honeycombed appearance to the surface of the stone. This form of decoration is especially effective when used in a large area. It is also used on window jambs.
Mortar is the "glue" that holds your masonry project together, binding building blocks and filling joints. It is available in a variety of hues and has specific characteristics to meet the needs of your build. A mortar that has a high bond strength will help withstand the elements and provide a long-lasting finish. Extent of…