This can happen in a number of ways including: exposure to the elements, reticulation or pool water spraying on the brickwork, incorrect mixing of mortar at the time of the build.
The cold tends to cause contraction and shrinkage of bricks and mortar - ever so slightly. Frozen droplets of water between joints actually expand and chip small bits of mortar away (ice takes up more space than water - don't freeze your beers!). This is known as spalling of the mortar.
Mortar Between Bricks Crumbling
Mortar between bricks that is noticeably crumbling should be removed at the earliest possible stage. Damaged mortar can subsequently be replaced with new mortar, in order to provide a robust and long lasting protection for the surrounding stonework.
This form of deterioration, known as spalling brick, is usually the result of water damage. It happens when water enters the brick or mortar and forces the surface to peel, pop out or flake off.
Crumbling or failing mortar can be caused by a number of reasons: Failing mortar can usually be attributed to a lack of carbonation of the lime within the mortar meaning that the mortar will have little if any, strength.
Applying fresh mortar on top of old mortar that is loose or falling out will do little or no good; enough of the old mortar must be removed to make room for a layer of new mortar that is at least half an inch thick, and even then it is important to make sure that what is left of the old mortar is still solid and ...
If your brick has already started to crumble, can it be repaired? Yes, it can. You may DIY, however, it's recommended that a professional does this so further structural damage doesn't occur. Crumbling and cracked bricks can be replaced with newer bricks and then sealed back into place.
TYPE N. The most common mortar mix is Type N. It is primarily used with brickwork and by most homeowners. This is the best choice for above-grade general applications and can be used for both exterior and interior load-bearing installations.
Mortar joints are considered deteriorated when:
Eroded back more than 1/4" from the face of the unit or beyond the depth of the original joint. Cracks are visible within the mortar. The bond between brick and mortar is broken or the mortar is soft and/or crumbling. Any portion of a mortar joint is missing.
Start with a visual inspection of the brick joints.
Look for signs of failing or missing mortar joints between the bricks. You may need to follow up by performing a probing test with a small knife. If the mortar is loose, crumbling, or falls out easily with digging, it is in need of repair or restoration.
However, the mortar used to hold the bricks in place has a lifespan closer to a quarter-century. Therefore, be prepared to replace the mortar every 25 years or so when it may show signs of cracking and crumbling. The repair and restoration process is called tuckpointing, also known as repointing.
This form of deterioration, known as brick spalling, is usually the result of water damage. It happens when water enters the brick or mortar and forces the surface to peel, pop out or flake off.
Mortar is generally very durable and has a typical lifespan of between 20-30 years, after which repairs (or repointing) can be necessary to fill cracks or gaps that may begin to appear.
Tuckpointing (or repointing) is the process of removing poor mortar from bricks and replacing it—usually, after the brick has been in place for years.
Mortar joints are typically 3/8", but can vary from 1/4" to 1/2" — we cover this more in our brick sizes article. Bed joints are the horizontal mortar joints, or the bed of mortar that the next brick sits on.
Type O mortar, or high-lime mortar, a softer mortar with a low compressive strength of 350 psi, is best suited to repointing for several reasons. The first reason is that type O mortar is softer than the older bricks, and it allows the bricks to expand or contract from temperature changes or stress.
Mortar is a mixture of sand and cements that is most often used to build brick or block walls. While that may sound like the same recipe used to make concrete, there are some intentional differences between the formulations for mortar and cement, which is why the materials should not be used interchangeably.
Repointing your brick walls is something you can do by yourself. It takes a little time and effort but overall, it's not too difficult.
In the last decade, there have been strides made in the materials that can be used to repair concrete instead. We now have polyurethane that can be used to lift concrete, build a boy beneath it, and fill in cracks in the concrete. These products are fast drying and more durable than products of the past.
In the winter, mortar contracts with cold temperatures, and freezing moisture within the masonry causes stress and damage. That constant stress on the mortar of your building causes deterioration over time. As the mortar weakens, it will eventually fracture.
The standard ratio for average mortar mix is 3:1 or 4:1 for bricklaying. If you are using a pointing mix, then you should have a ratio of 1:4 or 1:5 mortar to sand. As for concrete, it depends on the strength you need it to be at. Usually, it is good practice to mix concrete at 1:2 mix to materials.
MORTAR CURE TIME
Mortar typically will cure to 60% of its final compressive strength within the first 24 hours. It will then take about 28 days to reach its final cure strength.
Mixing for longer than necessary to give a uniform consistency adds a great deal of air to the mix, which weakens the mortar. The mortar should never be remixed or the old mortar should be introduced to the fresh batch. Older mortars should not be 'freshened up' or 'knocked up' by adding too much water.
Mildly crumbling bricks can often be stabilized with a sealer, but more serious spalling cannot be handled with DIY methods. Additionally, sealing your bricks will not address the underlying cause. If you believe serious water damage is the cause, you need the help of a professional.