5 Ratings, (9 Votes) The reason for the tooling of mortar joints is that it gives neat appearance and also helps in compaction of mortar. The tooling profiles that are suitable for a brick wall in a severe climate are vee joints and concave joints.
What is the effect of mortar joints on water?
This can lead to higher water contents in the mortar. To help mitigate these issues, the mortar specified for these types of masonry units should match the density and absorption properties of the masonry units as closely as possible. Mortars used for this application should, generally, have a low water retention and contain a water repellent admixture to properly match the masonry unit.
What causes mortar to mottle?
Surface mottling of masonry mortar occurs when on-site conditions and construction practices cause the extention or premature termination of the cement hydration. Densifying of the mortar at the surface of the mortar joint during finishing practices also can cause this surface condition. Hydration of portland cement cannot proceed if water is unavailable, making the mortar joint darker than desired. Conversely, if additional water is available during the curing process the cement can over-hydrate, yielding a lighter-than-expected result. Generally, the higher the water content in the mortar, the lighter the mortar. Mottling can manifest itself across the entire surface of the mortar joint or even in small, irregular patches.
What is mottling on mortar?
Similar to mottling in concrete surfaces, mottling on mortar joints is best described as generally darkened or discolored patches or areas that are adjacent to, or within lighter colored mortar on the surface of mortar joints. Mottling generally appears during the construction phase of the project and may or may not be associated ...
How to remove mortar smears from a masonry block?
If the mortar smears are removed by rubbing the units with a rag or towel directly after tooling, mortar material and surface water adhered to the rag can be transferred to the mortar surface. That can contribute to surface mottling. For densified or glazed masonry units, the use of an acrylic finishing tool is generally more successful than using metal finishing tools.
How to remove mottling from a sandstone?
The manual use of a “rubbing stone” or a stone drill bit, followed with washing the joints lightly with a mild cleaning agent has proved successful in removing surface mottling.
Why does grout hydrate?
However, the additional water provided by the grout can result in inhomogeneous paste where some areas hydrate more due to the presence of excess water, while other areas dry out. Excess moisture can migrate through the mortar and pick up soluble salts, such as calcium hydroxide, depositing them on the surface of the mortar upon drying. Exposure of calcium hydroxide to CO2 in the atmosphere rapidly converts the calcium hydroxide to calcium carbonate, which leads to light discoloration.
What is premocoat bonder?
Cresco Concrete Products’ Premocoat Bonder is used as an adhesion promoter for cement based coatings and an admixture to enhance UV and moisture resistance. Premocoat Sealer is a clear, acrylic sealer used to enhance the moisture resistance of finished cementitious surfaces or for making colored surfaces more vibrant and glossy.
What is the profile of a mortar joint?
The profile of the mortar joint is created when the jointer strikes against the surface of the mortar before the joint has set. We will highlight some of the most common types in this brief article.
Why is a raked joint not recommended for exterior use?
Raked Joint: The raked joint is another joint not recommended for exterior use because its ledge may allow water/snow/ice to sit on top of the brick. Due to the fact that the mortar sits back from the face of the brick, there is less cover between the face of the mortar joint and the top of the brick unit where the cores exist. ...
Why do we need a concave profile?
A concave profile is typically desired in repointing projects because it provides the best opportunity to compress the mortar and to shield moisture. However, consideration should be given to the aesthetic intent and historic significance of the project.
Why is the V joint not a concave joint?
If it isn’t tooled correctly, water can accumulate in the joint. Similar to the concave joint, tooling works the mortar tight and can help to prevent water penetration if done correctly.
Why does water sit on top of a brick?
If not given the proper care, water can sit on top of the joint if it sticks out from the brick. It is also difficult to maintain a consistent and sufficient bond to the brick because the mortar is not compressed into the joint with the striking tool. Squeezed Joint: The squeezed joint is commonly seen in indoor architecture or outdoor fences.
What is a weathered joint?
Weathered Joint: The weather joint is used to emphasize horizontal joints. The weathered joint helps shed water from the joint, however it is possible that water can run across the underside of the brick and get through if the mortar is not adhered tightly or if shrinkage cracks develop in the bond line.
Which joint is best for preventing water penetration?
Concave Joint . Concave Joint: The concave joint is the most common joint that is used, as it is also known as the best joint for preventing water penetration. Tooling works the mortar tight into the joints, which produces better weather resistance. V Joint: The V Joint does not protect from water as well as the concave joint because of its geometry.
What type of mortar is used for interior non-load bearing applications?
Type I mortar is recommended for interior non-loadbearing applications.
What is a good workable mortar?
Good workable mortar is typically composed of cement, sand, and water.
What is vertical mortar?
The vertical layer of mortar between ends of masonry units.
How many stretchers are needed for brickwork?
Brickwork laid with five courses of stretchers followed by one course of headers.
Why do brick walls need expansion joints?
Brick masonry walls require expansion joints to relieve stresses caused by the expansion of the bricks as they absorb water.
Why do we need one way slabs?
Major reason is to relieve potential stresses. Located where the edge of concrete slab abuts a a wall, also columns and load bearing walls. A one-way slab rests across parallel line of support furnished by walls or beams. The formwork of one-way slab is erected only after pouring of walls and columns.
What is the difference between mill and ordinary construction?
Ordinary construction uses floors, roof, and interior walls of balloon frame construction, while Mill construction uses heavy timber framing for internal construction. The heavy timbers and decking used in Mill construction are slow to catch fire. Ordinary construction is usually protected with plaster or gypsum board over the wood components, and by firestopping between floors. Wood members that bear on the masonry walls in either system are firecut to prevent them from toppling the wall should they burn through in a fire.
How is a quarry block cut?
The quarry block is sliced into slabs using a gang saw. The faces of the slab are ground flat, then polished smooth in a grinding and polishing machine. Finally, the edges of the slab are squared by a circular saw.
Is cement a part of concrete?
Cement is a part of concrete . The cement is a powder substance and when it is combined with water, it hardens into concrete.
Do you need to heat a masonry enclosure?
These enclosures may need to be heated in very severe weather . The masonry units, sand, and water should be heated as required.
