Efflorescence

The best way to prevent the problem is to prevent water from infiltrating the wall.

If you see efflorescence crystals it usually means there is a leak somewhere letting outside water in. Once, the source of the water infiltration has been located and stopped then the walls can be cleaned with an efflorescence remover. While inside systems can divert the water, it may not solve the problem of efflorescence and other moisture-related mineral build-ups.

Regardless of what is done on the inside, water is still entering through the wall from the outside. The salt that ends up as efflorescence crystals on your walls, can come from salt laden soils or the Portland cement in the mortar and grout. The soluble salts could come from the sand or from contaminated water used to make the concrete, grout or mortar. Another culprit is, of course, the clay brick itself.

• Efflorescence.
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The natural clays used in the manufacture of brick often contain soluble alkali sulfates. Most modern fired clay brick have balanced chemical additives to immobilize the sulfates and render them insoluble. This prevents the salts from being dissolved into a solution that could migrate through the wall to the surface. Most fired clay brick do not greatly contribute towards the efflorescence problem. The traditional method of cleaning efflorescence has been sandblasting, which, of course, works. Unfortunately it removes just about everything else, too. The abrasive action of the sand erodes the surface of the brick and the tooled mortar joints along with any deposited salts.

This increases the porous qualities of the masonry and the water absorptive nature of the wall. Sandblasting should be used with caution and afterwards the masonry should be sealed with a waterproofing material. An alternative to sandblasting, which has shown good success when done properly is the use of special chemical cleaners.

efflorescence

Generally, thorough presoaking and post washing with clean potable water is required. Some people describe a reverse process, where the salt is originally present externally and is then carried inside in solution, as "secondary efflorescence. Efflorescences can occur in natural and built environments. Primary efflorescence is named such, as it typically occurs during the initial cure of a cementitious product. It often occurs on masonry construction, particularly brick , as well as some firestop mortars , when water moving through a wall or other structure, or water being driven out as a result of the heat of hydration as cement stone is being formed, brings salts to the surface that are not commonly bound as part of the cement stone.

As the water evaporates, it leaves the salt behind, which forms a white, fluffy deposit, that can normally be brushed off. The resulting white deposits are referred to as "efflorescence" in this instance. In this context efflorescence is sometimes referred to as "saltpetering. For controlling primary efflorescence, formulations containing liquid fatty acid mixtures e.

The oily liquid admixture is introduced into the batch mix at an early stage by coating onto the sand particles prior to the introduction of any mix water, so that the oily admixture is distributed uniformly throughout the concrete batch mix. Secondary efflorescence is named such as it does not occur as a result of the forming of the cement stone or its accompanying hydration products.

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Rather, it is usually due to the external influence of concrete poisons, such as chlorides. A very common example of where secondary efflorescence occurs is steel-reinforced concrete bridges as well as parking garages. Saline solutions are formed due to the presence of road salt in the winter. This saline solution is absorbed into the concrete, where it can begin to dissolve cement stone, which is of primary structural importance.

Virtual stalactites can be formed in some cases as a result of dissolved cement stone, hanging off cracks in concrete structures. Where this process has taken hold, the structural integrity of a concrete element is at risk. This is a common traffic infrastructure and building maintenance concern. Secondary efflorescence is akin to osteoporosis of the concrete. For controlling secondary efflorescence, admixtures containing aqueous-based calcium stearate dispersion CSD are often added at a later stage of the batching process with the mix water.

In a typical batching process, sand is first charged into the mixer, then the oil-based primary anti-efflorescence admixture is added with constant mixing to allow the oil to coat the sand. Then coarse aggregates, colorants, and cement are added, followed by water. If CSD is used, it is then introduced usually at this point during or after the addition of the mix water. CSD is an aqueous dispersion wherein fine solid particles of calcium stearate are suspended in the water uniformly. Commercially available CSD has an average particle size of about 1 to 10 micrometres.

In many instances, efflorescence may occur during home construction. If masonry units are left out overnight during construction, they can absorb moisture from damp soil and rain. It is essential for masonry units to be covered and left in pallets to minimize the risk of efflorescence throughout a construction project. Efflorescence is often a seasonal problem, and humidity will impact whether soluble salts appear. It usually escalates in winter, since rain, snow, sleet and other inclement weather conditions may arise.

However, efflorescence can still occur in spring, fall and summer. Understanding the differences between efflorescence and stains is critical. Stains usually come in various colors but may appear similar to efflorescence at first. Efflorescence is a white, powdery substance that can be found on unsealed surfaces, including:. Since it is a porous material, brick may absorb soluble salts. To find out whether efflorescence will be a problem for your brick, take a single brick and immerse it in distilled water for approximately seven days. Let the brick dry after the seven days and compare it to a brick that was not immersed.

If you notice a white, powdery material on the brick, it likely has effloresced. Portland cement represents the key contributor to efflorescence in mortar and grout , according to the Brick Industry Association BIA.

Basement Questions: Efflorescence

It is high in alkalis and is more likely to effloresce than other types of cement. Conversely, it is important to note that all types of cement contain some water-soluble alkalis, making any cement susceptible to efflorescence. Comparatively, lime also has been shown to improve the bond between mortar and brick and increase the water resistance of masonry materials. Sand is used in mortar and grout and is not water-soluble.

On the other hand, sand can be contaminated with a material that can contribute to efflorescence. For building projects, using clean, washed sand that comes from sources free of contamination will minimize the chance of efflorescence developing.

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Building brick and face brick consist of clay, which contains highly soluble salts. Clay may react with calcium sulfate that results in efflorescence. Generally, it is better to err on the side of caution with admixtures. If you do not know what is included in the admixture itself, you may want to avoid this solution entirely. Concrete and other backing materials may contain soluble salts, contributing to efflorescence of brickwork. If sufficient water is present in backings, salts may dissolve, causing the backing materials to effloresce. Caps, keystones and other trim may consist of building materials with soluble salts that can be difficult to control.

As such, you should consider which trim materials to use before you start a building project to reduce the chance of efflorescence. Any building materials that come into contact with the ground may be susceptible to efflorescence. But if you know the root causes of efflorescence, you can select the right building materials and prevent this problem from occurring. Choosing the right building materials is paramount for any building project. If you understand the impact of efflorescence on various building materials — and how to spot efflorescence — you should have no trouble minimizing this problem.

Porous building materials such as concrete, pavers and stucco can absorb or wick water and draw salts to it. The International Association of Certified Home Inspectors InterNACHI points out porous building materials can absorb or wick water over a six mile span, carrying it through the materials like a tree transports water from its roots to its leaves.

This is known as capillary action. When efflorescence happens, it can be indicative of a moisture issue that could potentially damage the structure. After the water evaporates, salt is left behind, but water absorption and wicking continue. This creates a high salt concentration, leading to osmosis. During osmosis, water moves toward salt to reduce its concentration, causing large hydrostatic pressures within the porous building material. As a result, these pressures can damage or destroy the material. InterNACHI states osmosis can cause pressure that ranges from 2, psi to 3, psi, exceeding the structural strength of concrete.

Therefore, osmosis may result in porous building material cracking, flaking or falling apart. Osmosis also may result in spalling, the separation of a building material due to hydrostatic pressure. However, it can lead to potential moisture problems that can cause structural damage to building materials.

Secondary Efflorescence

Applying an impregnating hydrophobic sealant to a building material surface can prevent the absorption of water. The sealant also will stop water from traveling within a building material. Installing capillary breaks such as polyethylene sheeting between a building material and soil can minimize the risk of salt entering the material. Implementing overhanging copings, eaves and flashings will minimize the risk of water from entering a wall.

Paying special attention to landscaping and sprinklers will ensure you can prevent water from reaching porous building materials. Consolidating grout with mechanical vibration will limit the chance of voids in the grout.