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What Is Concrete Waterproofing?

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    The method of waterproofing concrete makes the concrete impermeable to the penetration of water. The application of specialised coatings, the injection of chemical substances into the surface of the concrete, or the installation of an additional waterproof membrane beneath the concrete are all viable options for accomplishing this goal. We'll take a look at some of the choices accessible to homeowners who want to safeguard their property and the investment it represents, as well as what each of these safeguards entails, in the next section.

    A coating might be applied on top of the layer you already have to help seal cracks and stop water from getting into your foundation through the walls. This would be one option. The fact that the majority of coatings may be applied without the assistance of a professional and are simple to use is one of the main features of this alternative (make sure you follow all instructions closely).

    What Is Waterproof Concrete?

    When it comes to the many various varieties of concrete that are available, it can be challenging to determine which characteristics are essential. This article will walk you through the characteristics of waterproof concrete and explain why having those characteristics can be so vital for ensuring high-quality, high-quality work.

    Isn't Concrete Already Waterproof?

    The typical concrete does not completely repel water. The words can be confusing, but waterproof concrete is the same thing as damp-proof concrete and watertight concrete. This means that not only is soil moisture prevented from getting through to the concrete, but liquid water cannot penetrate it either.

    Concrete is porous by nature as a result of the chemical reactions that occur during the curing process: water is mixed with cement and aggregates, and as the mixture hardens, the excess water escapes, creating a web of capillaries within the concrete.

    Concrete is porous by nature because of these chemical reactions. This indicates that concrete is capable of absorbing a significant quantity of water, approximately 60 litres per cubic metre of good quality concrete in just 30 minutes; nonetheless, the rate at which this transpires can induce dampness depending on how quickly it takes place.

    What Happens When Concrete Is Too Damp?

    what is concrete waterproofing 2

    In the long run, this can result in erosion as a result of moisture and water penetrating the pores and forming cracks; the more cracks that appear, the greater the likelihood that water will penetrate the surface. This process happens very gradually, so it can take a while for signs to show, but if the surface of the concrete begins to look slightly worn, you can guarantee that the inside structure is deteriorating as well.

    This can be a good indicator of whether or not the structure has been maintained properly. Fixing this can be a significant undertaking, not to mention an expensive one. Because of this, it is always advisable to invest in good quality concrete rather than trying to cut corners. Concrete that is inexpensive to purchase will cost a great deal more to repair in the long run.

    What Are The Benefits Of Waterproof Concrete?

    When it comes to large building projects, waterproof concrete offers a number of benefits in terms of its performance and its endurance, including the following:

    • Structure that is strengthened because waterproof concrete absorbs less moisture, which results in fewer fractures and makes the structure less susceptible to damage from outside forces.
    • Reduces the expenses of maintenance since there is less wear and tear, which results in fewer hours and less dollars spent on repairs.
    • Mold and mildew can be avoided by avoiding dampness, which in turn eliminates the spores that cause mould and mildew. This lowers the likelihood of getting sick and makes for a healthier environment.
    • A basement or subfloor that is waterproof is a wonderful selling factor for a house since it reassures potential buyers that they won't have to deal with any issues related to water in the future. This results in an increase in the property's value.
    • Keeps a clean look since waterproofed concrete won't decay from being exposed to water, thus it won't show signs of wear and tear as quickly as regular concrete would.

    When Would You Need To Use Waterproof Concrete?

    Along with many big above-ground constructions that would benefit from being able to tolerate water, waterproof concrete is ideal for uses below earth, where it must be impermeable. In addition, waterproof concrete is best for applications below ground. Take, for instance:

    • Basements
    • Garages located underground
    • places with a high water table
    • constructing locations that are prone to flooding and have high rainfall amounts
    • Tall structures and skyscrapers

    Why Waterproofing Is Required For Concrete

    In places below grade, it is vital to waterproof the concrete in order to prevent water from penetrating the structure and causing damage.

    We have used up all of the building sites in many parts of the world that had a good drainage pattern that was naturally present in the high-ground terrain that was formerly abundantly available. As a result of this attrition, we discover that the only sites that are both handy and available are low-lying areas that are either in or near flood plains, swamps, rivers, and lakes, etc.

    In addition to having higher water tables and the water pressures that come along with them, these regions also provide us with the possibility of even higher water heads as development in the surrounding area continues. In addition to this, we are also dealing with the fact that the water levels in many of the lakes and rivers have already begun to rise. In many of these locations, there are also other pollutants that are known to have a negative impact on certain kinds of concrete and concrete masonry units.

    Below-grade concrete surfaces absolutely need to be waterproofed for a variety of different reasons. The primary goal is to prevent moisture from entering the building under any circumstances. Nevertheless, it is necessary in order to protect the structural contents from water penetration, which has the potential to cause structural damage to the concrete or corrosion to the steel that is embedded in the concrete.

    Concrete is purposefully made to be a porous material, and it is possible for water to move through it via capillary action, hydrostatic pressure, or the water vapour gradient. Cracks, structural faults, and joints that were either poorly designed or inadequately built are other entry points for water. In addition to this, waterproofing is essential in order to prevent the deterioration of the concrete that may be caused by the interior and outside chemicals that are present at the construction site.

    Susceptibility Of Concrete To Chemicals

    Because of its permeability, alkalinity, and reactivity, concrete is susceptible to the effects of chemical exposure. This makes concrete an unreliable material for chemical containment. There is a significant amount of variation between the types of concrete in terms of their permeability to liquids and gases. Permeability exists, albeit to a very slight degree, even in the best concrete. When the percentage of water to cement is increased, permeability increases at a much faster rate than when the amount of time needed for curing with moisture is decreased. When fluids penetrate concrete, it can sometimes set off chemical reactions with the cement, aggregates, and embedded steel, if any of those are present. Degradation of the system can also occur as a result of the leaching of cement hydration chemicals, the deposition of extraneous crystals, or the formation of crystalline reaction products.

    When it comes into contact with acidic things, the alkaline hydrated Portland cement binder will react. This reaction is typically accompanied by the creation and removal of soluble reaction products, which ultimately results in the disintegration of the concrete. When the products of the reaction are insoluble, deposits can form either on the surface of the concrete or within the concrete itself. This results in a significantly slower reaction rate. In most cases, increasing the concentration of aggressive agents in the solution will result in a corresponding increase in the rate of attack.

    Depending on the pH factor of the solution, the solutions can either be acidic, neutral, or alkaline in nature. The pH scale begins at 7 for solutions that are neutral. The pH value of acidic solutions is less than seven, while the pH value of alkaline solutions is greater than seven. As the pH level falls below 7, the solution becomes more acidic, which makes it more destructive to concrete as it works its way through the aggregate.

    The physical state of the chemical agent is also an essential consideration. For instance, dry solids are incapable of breaking down dry concrete. On the other hand, they are capable of breaking down wet concrete. Concrete can be broken down just as easily by an aggressive liquid or solution as it can by a reactive, moist solid. Dry gases may come into touch with sufficient moisture within the concrete to make the attack conceivable if they are aggressive. This might happen if the gases are hostile. Gases that are moist and aggressive have a tendency to cause more damage.

    Wetting and drying in alternating cycles can be harmful to the structure of concrete and can ruin it owing to an alkali-aggressive response. This takes place when the dissolved substances move through the concrete and deposit themselves at or near a surface where evaporation takes place. The resulting deposit may be the substance that was initially present, or it may be the product of some reaction that occurs within the concrete. As a direct consequence of this, efflorescence may appear on the concrete walls, brick, or stone.

    When concrete goes through cycles of freezing and thawing, salt solutions can be more damaging to the material than just water alone. However, the amount of damage that can be caused by water or salt solutions can be reduced by deliberately incorporating a sufficient amount of air into the concrete. High-quality concrete will be able to produce air bubbles of the appropriate size, spacing, and distribution if this step is taken first.

    Concrete can be ruined by a variety of different substances. These kinds of compounds are frequently found in the soil or in the surroundings surrounding a construction that is located below ground level. Before beginning work on the waterproofing system design, it is the designer's obligation to ensure that the soil has been subjected to a complete and accurate chemical examination.

    The presence of these compounds may potentially be detrimental to the efficacy of the waterproofing barrier. Acid waters, aluminium chloride, aluminium sulphate, ammonia vapours, ammonium sulphate, ammonium chloride, ferric sulphide, and ferrous sulphate are some of the most destructive chemicals to concrete. These chemicals can all disintegrate concrete and attack steel. Other destructive chemicals include ammonia vapours, ammonium sulphate, and ammonium chloride.

    In addition to chemical attacks from organic and mineral acids, the deterioration of concrete can also be caused by some things that contain acid or produce acid, such as acidic industrial wastes, hay, fruit juices, sour milk, weakly based salts, and some untreated waters. It's also possible for ammonium salts and animal excrement to oxidise and attack the concrete, leading to some degree of deterioration.

    Concrete is attacked by a wide variety of chemicals, each of which uses reaction processes that are either partially or inadequately understood to bring about detrimental changes in the chemical composition of the concrete. For instance, seawater may be damaging to concrete that is permeable or that is produced with cement that has a high percentage of tricalcium aluminate. This may be due, in large part, to the fact that seawater contains sulphate. The typical cause of the deterioration is the leaching of calcium from the concrete, which occurs when the calcium dissolves.

    Concrete can be damaged by certain chemicals, but not all of them. The majority of carbonates and nitrates, as well as certain chlorides, fluorides, and silicates, are examples of common neutral salts that do not react negatively with concrete. In most cases, the addition of limewater to concrete is good since it speeds up the hydration process while simultaneously preventing the loss of lime from the concrete.

    The majority of other mildly alkaline solutions are safe to use. Products generated from petroleum are typically innocuous to mature concrete when they do not contain fatty oil additives or any other potentially acidic components. However, some of these materials can create unsightly discoloration of the concrete.

    Cracks, Openings And Points Of Infiltration

    Concrete constructions need to have waterproofing applied to them in order to prevent moisture from entering the building and to safeguard the structural components of the concrete as well as the embedded reinforcing steel. It is possible for the concrete to retain its waterproof qualities if its integrity is preserved. However, cracks can appear in concrete both before and after it has had time to solidify, and each of these cracks becomes an aperture that is susceptible to the invasion of moisture.

    Concrete has the potential to crack before to reaching its final hardened state as a result of building movement, plastic or drying shrinkage, or early frost damage. After the concrete has hardened, it is possible for the material to crack as a result of soil movement, settlement, seismic pressures, vibration, creep, excessive stress, or deflection.

    In addition to being a material that is porous, concrete is vulnerable to the infiltration of moisture in multiple spots throughout the material. Points of moisture infiltration include all concrete joints, control joints or expansion joints. Additionally, holes for tie rods, penetrations, and structural connections can also be the source of openings. Drains on the inside of buildings can serve as points of entrance for moisture.

    The question of whether or not waterproofing on the positive side is preferable than waterproofing on the negative side is one that is frequently discussed. When weighing the pros and cons of this option, one should never forget that the obligation of safeguarding the structure falls on the shoulders of the waterproofing. The use of negative side waterproofing will not allow for this to be performed. If you want your waterproofing to be effective, you should always apply it on the side of the structure that has a positive hydrostatic pressure.

    When any system is installed on the side of the structure that experiences negative hydrostatic pressure, the installer assumes the risk that the waterproofing system will be dislodged or pushed off by moisture that penetrates the concrete in the form of either vapour or liquid. When a structure's weaker side is waterproofed, there is a greater likelihood that any contaminants that may be present in the ground moisture may be drawn into the concrete mass.

    Treatment Of Concrete Surface Defects

    The condition of the concrete surface is an essential component that has a significant impact on the performance of waterproofing systems. It is necessary to have a smooth surface that is essentially free of honeycombs, depressions, fins, holes, humps, dust, dirt, oils, and any other surface contaminants in order to provide continuous support to the waterproofing material and good adhesion between the membrane and the substrate. Other surface contaminants include: The action of water pressure on material that is not supported may cause the material to extrude, deform, and eventually break.

    It is also vital to have good adhesion between the concrete surface and the waterproofing membrane in order to minimise water migration and leakage in the case that either the membrane or the concrete surface contains any gaps or defects. Before the waterproofing application, any form coatings, release agents, or concrete curing membranes that could potentially interfere with the formation of good adhesion should be removed.

    In the section of the requirements devoted to concrete, the designer needs to stipulate the correct preparation of the substrate. Concrete placement and waterproofing treatments are often completed by different trades, which can lead to miscommunication and other issues. The correct preparation of the concrete and the question of whose obligation it is to carry out the necessary repairs before applying the waterproofing material are frequently at the heart of disagreements.

    Concrete repair must be included as one of the specific concerns that are addressed in the design requirements. Other issues that must be addressed include the removal and repair of any surface flaws that occur during construction. The production of precast concrete often takes place in a shop setting. When fresh cast-in-place concrete is being poured, it is important to repair any sharp offsets that exist between the precast pieces. Immediate attention should be paid to the rectification of any surface faults, including tie holes, as soon as the forms have been removed.

    It is recommended that all honeycombed and faulty concrete portions be removed until sound concrete is exposed. If it is important to ship the item, the edges should be trimmed such that they are either perpendicular to the surface or undercut slightly.

    There should be no allowance for feathery edges. In order to prevent water absorption from the patching mortar, the area that is going to be patched as well as a band that surrounds it measuring roughly 6 inches should be dampened. To make a bonding grout or bond coat, you need produce a mixture that consists of approximately one part cement to one part fine sand, and it should be brought to the consistency of thick cream. The mixture ought to be rubbed in uniformly all over the surface.

    Chipping, hammering, or wire brushing should be used to bring any protrusions, fins, or other similar abnormalities that are extending from the surface of the concrete back down to the surface level. For the application of the waterproofing membrane system, care should be taken to obtain a surface that is reasonably planar as much as possible. In order to produce gradual and smooth transitions between the offset surfaces, sharp offsets in the surface, such as those generated by formwork misalignment, should be mechanically abraded.

    This will provide the best results. Certain waterproofing systems do not require all concrete surfaces to remain within the same plane as long as the transitions are gradual and smooth. This is one of the conditions under which these systems can be used. When faced with such circumstances, one should get in touch with the waterproofing manufacturer to enquire about special requirements.

    Before using the appropriate patching material to fill in tie rod holes, those holes should first be properly cleaned out and then dampened.

    Concrete Surface Preparation

    It is essential to pay close attention to the preparation of the surfaces that are going to receive the waterproofing materials if you want to accomplish the goal of achieving an acceptable bond strength. The quality of the surface preparation is critical to the performance of the waterproofing. It is imperative that the waterproofing membrane's adhesion capabilities are not compromised by the presence of chemicals on the concrete surface, since this would render the membrane less effective in its intended function.

    The surfaces ought to be freshly exposed concrete that is devoid of any items that are loose, fragile, or otherwise unsound. Concrete surfaces ought to be typically dry; nevertheless, certain manufacturers of waterproofing membranes permit the placing of their materials over damp concrete surfaces. Concrete surfaces ought to be dry.

    When faced with such circumstances, one should get in touch with the waterproofing manufacturer to enquire about special requirements. While the concrete is curing, special attention must be paid to ensuring that moisture does not accumulate at the point where the waterproofing membrane meets the concrete. A series of tests ought to be carried out in order to ascertain whether or not the surface has been adequately prepared before the application of the waterproofing membrane. Before work can begin on the project, there are a few crucial aspects that need to be examined, the most important of which are the prepared concrete's strength and the membrane's capacity to attach to the concrete.

    Ensuring A Successful System

    Waterproofing is required in sensitive and occupied areas, as concrete is susceptible to moisture infiltration. The condition of many concrete roads and driveways attests to the dangers moisture infiltration can pose. The effectiveness of the waterproofing system will be contingent on the concrete surface being correctly prepared. Before the application of waterproofing, any surface imperfections in the concrete must be satisfactorily remedied.

    As an architect, you should do your utmost to include appropriate guidelines for the concrete surface in the initial design. This will eliminate conflict that can arise between the different trades that are typically involved in waterproofing applications. This will lead to success in one of the building's components that is both one of the most complex to design and one of the most litigated.

    Waterproof Concrete: Is It Enough For Protecting Foundations?

    what is concrete waterproofing

    The process of waterproofing a structure protects both the structure and the assets contained within it against the destructive effects of moisture, humidity, and floods. Even though waterproofing systems only make up a small portion of the total cost of a building project, the costs of remediation can be quite expensive if the wrong solution is selected or if it is built badly.

    Risk Of Water Ingress

    In most cases, the amount of water utilised in concrete production is far higher than the minimum amount needed to hydrate the cement. This surplus of water fills up space in the concrete, resulting in the formation of a network of capillary gaps. Because of this, channels are created through which water can infiltrate the concrete when it is subjected to hydrostatic pressure or the action of capillary forces. When a foundation is built at or near the water table, or in places where heavier soil is more likely to carry more moisture, the danger of water ingress is considerably higher. This is also true of foundations built in locations where heavier soil is more likely to convey water.

    Creating Waterproof Concrete

    In order to produce concrete that is waterproof, waterproof admixtures are utilised. By lowering both the permeability and the drying shrinkage of the concrete, the admixtures lessen the likelihood that water will penetrate the structure.

    When To Use Waterproof Concrete

    It is recommended to use waterproof concrete, which is also known as integral concrete, for water-retaining structures and basements that are less critical and are less than 10 metres deep. This is because the soil conditions in these areas are not particularly aggressive, and the effects of flooding are not as severe. This includes unfinished, fundamental utility spaces like car parks and workshops, where a certain amount of seepage and damp patches are acceptable.

    Advantages And Disadvantages Of Waterproof Concrete

    Waterproof concrete has a number of benefits, two of which are its low material prices and its ease of application. A specialised additive is blended into the ready-mixed concrete by the manufacturer of the ready-mix as a step towards producing watertight concrete. As a consequence of this, the general contractor does not need to be concerned about allocating separate time for the process of waterproofing the concrete.

    When you depend on the concrete to be waterproof, however, you need to pay additional attention to the quality of the concrete installation and finishing, as well as the selection of the raw materials. Honeycombing, shrinkage cracks, or structure cracks that allow water to permeate the structure can be the result of poor casting and vibration, insufficient curing of the concrete, and aggregates of poorer quality. These problems can also be caused by using aggregates of lesser quality.

    In addition, including water in the mixture when the concrete is being transported can reduce the material's ability to pass water and air through it. In order to alleviate these issues, a high-quality concrete mix and effective quality control are essential, but they might be difficult to achieve given the constraints of the project's budget and schedule.

    Repairing Waterproof Concrete

    Cracks are inevitable in concrete. Cracking can be caused by a number of factors, including temperature-related stresses, shrinkage, and related difficulties. Water may find its way through even the slightest of cracks. Cracks can be minimised with the addition of waterproof concrete admixtures, but they can't be eliminated entirely.

    Injection grouting is often what is done to fix problems with waterproof concrete after it has failed. However, because water can move around within the concrete slab or the walls of the concrete building, it may be challenging to locate the source of the leak in these kinds of scenarios. Since there is no way to remove the water once it has penetrated the concrete, this can lead to major issues such as mould, which can be expensive to cure.

    However, there is no other way to prevent these issues from occuring. Because it would be difficult and time-consuming to have to open up walls in order to inject grout, waterproof concrete should be reserved for low-risk areas that have not been finished. This is one of the reasons why. It can be extremely challenging, if not impossible, to obtain access to leaks in deep basements in order to locate and repair them.

    When Waterproofing Concrete Isn't Enough

    Pre-applied waterproofing membranes are preferable to waterproofing concrete in situations where finished spaces must have a dry environment, utility rooms and storage spaces, or deep basements with limited tolerance for water vapour are involved. This is because pre-applied membranes can resist hydrostatic forces that would otherwise push water into the structure if waterproofing concrete were used. When using a pre-applied waterproofing method, the waterproofing barrier is installed prior to the pouring of the concrete slab and the walls. After that, the concrete is poured on top of the membrane, creating a bond that repels water and other forms of moisture.

    The membrane, which has fully bonded and pre-applied waterproofing, effectively compensates for any structural faults that may occur. For instance, even if there are breaches in the waterproof membrane as a result of ground subsidence, it should still be attached to the concrete. In addition, the strength of the bond between the concrete and the membrane should make it so that any problems that arise with repairs are kept to a minimum. This connection stops water from flowing laterally, which means that if a leak does develop, it will be easier and less expensive to pinpoint the source of the leak and repair it than it would be if the structure were waterproofed with concrete.


    The process of building a barrier between water and concrete is what is referred to as "concrete waterproofing." This can be accomplished in one of two ways, either through an application that is public or one that is private. Because they are less expensive than establishing an underground tank system to retain liquid that will eventually seep into the earth surrounding your foundation wall and produce a natural moisture barrier from the inside, external applications are the most popular type.

    However, because it is dependent on gravity to function well, this version does call for a greater amount of care. Internal applications are also more durable, but they need you to excavate a portion of your basement so that installers can run pipes filled with the material through them before filling the space back in. This is done to conceal any evidence of work that has been done below grade level.

    Frequently Asked Questions About Concrete Waterproofing

    Waterproofing is required at concrete structures to keep moisture out of the facility and protect the structural components of concrete and embedded reinforcing steel. If the integrity of the concrete is maintained, it can remain waterproof.

    It is very important to waterproof your home or building from all possible damage. However, no waterproofing can lead to cracks, paint peel off and even moulds, mildew and air contaminants. It is also a great risk for the structure and foundation of the building.

    Waterproof concrete admixtures help reduce cracks, but they don't eliminate them. ... However, it can be difficult to isolate the source of the leak in these situations since the water can migrate within the concrete slab or concrete walls.

    For every sheet membrane I know of, concrete must be cured a minimum of seven days before membrane application, sometimes even longer. This is because the concrete will continue to dry long after it's poured. In addition, the water vapour escaping from the concrete can prevent the waterproofing material from bonding.

    For example, if a concrete substrate is damp, the normal procedure is to use a moisture barrier before applying the waterproof membrane. Often waterproofing membranes will have a "short dry time", but this doesn't include the need to apply several coats in the waterproofing process.

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