In many areas of the world, we have exhausted the building sites having the good drainage pattern inherent in previously abundantly available high-ground topography. Through this attrition, we are finding the only convenient, and available sites are located in low-lying areas in or near swamps, flood plains, along rivers and lakes, etc. These areas, with higher water tables and their concomitant water pressures, are also presenting us with possibilities of even higher water heads as nearby development proceeds. We have, also, the rising water levels already being experienced in many of the lakes and rivers. Many of these sites have the additional problems of contaminants known to affect many types of concrete and concrete masonry units adversely.
Waterproofing is required at below-grade concrete surfaces for several reasons. The primary reason is to keep moisture from intruding into the facility. However, it is also required to protect the structural contents from water infiltration that can cause structural damage to the concrete or corrosion to the embedded steel. Concrete is by design a porous material, and water can pass through it by hydrostatic pressure, water vapour gradient or capillary action. Water can also enter at cracks, structural defects or at improperly designed or installed joints. Waterproofing is also required to eliminate deterioration to the concrete that can occur from the exterior and interior chemicals that are present at the building site.
When you are waterproofing concrete, masonry and other cement-based materials you prolong the life and durability of the structure. Whether you are preserving a cinder block wall, a concrete floor or poured concrete walls, keeping water out of concrete is a great step toward better longevity. In some parts of the country, if you have masonry, concrete or block walls, it is required by law and building code to waterproof these structures. A high water table, flood-prone building area or high rain levels dictate these types of waterproofing codes. In high-rise buildings, all substructures have to be waterproofed. They are load-bearing walls for incredibly heavy complexes, and a material breakdown is unacceptable.
At Hitch Property Constructions, we offer the best range waterproofing services to rectify your water issues.
Water breaks concrete down.
Not only does it start looking bad, but it’s also getting weaker. You have probably seen surface damage on a sidewalk or old mortar. The concrete erodes, exposing matrix materials and base concrete. In extreme cases, water will destroy concrete quickly, but generally, it takes a few years to start showing. If you see damage on the surface of the concrete, it’s a safe bet the underlying structure of your wall or floor is damaged too. If you want a concrete project to maintain its strength and fresh appearance, you need to waterproof it. When you waterproof concrete, you are also protecting the re-bar inside the concrete from rusting and eroding.
Risk of water ingress
Usually, the amount of water used in concrete is much more than is required to hydrate the cement. This excess water takes up space in the concrete, forming a network of capillary voids. This provides channels for water to penetrate the concrete when subjected to hydrostatic pressure or capillary action. The risk of water ingress is even higher when the foundation is being built at or near the water table or in areas where there is heavier soil that’s prone to carry more moisture.
Creating waterproof concrete
Waterproof admixtures are used to create waterproof concrete. The admixtures reduce the chance of water ingress by reducing the permeability and drying shrinkage of concrete.
When to use waterproof concrete
Waterproof concrete (also called integral concrete) is generally best for water retaining structures and less critical basements that are less than 10 meters deep, where soil conditions are not aggressive, and where the consequences of flooding are less severe. This includes unfinished, basic utility spaces such as car parks and workshops where some seepage and damp patches are tolerable.
Advantages and disadvantages of waterproof concrete
Low material costs and ease of application are two advantages of waterproof concrete. To produce waterproof concrete, the ready-mix producer incorporates a special admixture into the concrete. The general contractor doesn’t have to worry about allowing time for waterproofing the concrete separately.
However, extra care is needed in the workmanship of concrete placement and finishing as well as the selection of raw materials when you rely on the concrete being waterproofed. Poor casting and vibration, insufficient curing of the concrete, and lower quality aggregates can result in honeycombing, shrinkage cracks, or structure cracks that will allow water to penetrate the structure. Besides, adding water to the mix while the concrete is in transit can compromise the permeability of the concrete. A good concrete mix and proper quality control are important for alleviating these problems, but challenging to meet given project budget and schedule pressures.
Repairing waterproof concrete
All concrete cracks. Shrinkage, temperature-related stresses, and related issues all cause cracking. Even the tiniest crack is a path for water. Waterproof concrete admixtures help to reduce cracks, but they don’t eliminate them.
When waterproof concrete fails, injection grouting is typically used to address it. 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. This is not only expensive to fix, but it can lead to serious problems like mould since there’s no way to remove the water once it’s in the concrete. This is another reason why waterproof concrete is best left for low-risk, unfinished spaces because having to open up walls for injection grouting would be troublesome and expensive. In deep basements, in particular, it is difficult if not impossible, to gain access to locate and repair leaks.
When waterproofing concrete isn’t enough
For finished spaces that require a dry environment or utility rooms/storage spaces or deep basements that have limited tolerance for water vapour, pre-applied waterproofing membranes are preferable to waterproofing concrete, because they can resist hydrostatic forces that would otherwise push water into the structure. With pre-applied waterproofing, the waterproofing barrier is placed before the concrete slab and walls being poured. The concrete is then poured on top of the membrane, forming a bond to keep water and moisture out.
With fully bonded, pre-applied waterproofing, the membrane essentially compensates for structural failures. For example, if gaps form due to ground settlement, the waterproof membrane should remain affixed to the concrete. Besides, any repair issues should be minimal due to the strength of the bond between the concrete and the membrane itself. This bond prevents water from migrating laterally, so if a leak does occur, it’s easier and less expensive to isolate it and fix it than it would be with waterproofing concrete.
Another major advantage of pre-applied membranes like the PREPRUFE® Plus membrane is the protection it provides from harmful gases in the soil. This helps to reduce potential health risks for building inhabitants. This is a major advantage when building in areas where the soil has high amounts of methane or radon, or where there is soil contamination.
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Guide to Concrete Waterproofing
Crystalline Concrete Waterproofing
This is a permanent method of waterproofing concrete as the waterproofing itself becomes part of the concrete. Crystalline concrete waterproofing works by using a crystalline compound that reacts with water and concrete. The result of this reaction is that millions of tiny crystals grow within the concrete, filling up the gaps, hairline cracks and pores. Because the tiny gaps and pores within the concrete are filled, water cannot penetrate through at all – the concrete is completely waterproof.
A sealer is a more common method of waterproofing concrete, and you can choose from a penetrating sealer or a coating sealer. A penetrating sealer sinks into the concrete itself and reacts with it in order to provide protection against water and other substances. Penetrating sealers are great if you don’t want to change the look of the concrete at all, such as when you’ve used coloured concrete or otherwise applied a treatment to it. A coating sealer forms a film over the top of the concrete, and the film stops water from getting through. Coating sealers can be clear or coloured and are very easy to apply. Be aware that both penetrating and coating sealers may need to be reapplied over time, however.
Concrete Waterproofing Membranes
A concrete waterproofing membrane is a waterproofing agent available in either sheet or liquid form. Sheet membranes are applied to the concrete using an adhesive and provide a permanent, waterproof barrier when correctly applied (with the necessary overlaps etc.). A liquid membrane is applied using a roller, paintbrush, or spray gun, and it dries to form a rubbery membrane that completely covers and waterproofs the concrete. These membranes are incredibly effective but may need to be repaired if they get torn or damaged in any way.
Cementitious Concrete Waterproofing
Cementitious concrete waterproofing is an effective method of waterproofing. It works by using a mix of a cement-based compound, additives, water, and bonding agents that are applied to concrete in a slurry form. The slurry then dries, and it completely waterproofs the concrete.
Treatment of Concrete Surface Defects
An important factor affecting the performance of waterproofing systems is the quality of the concrete surface. A smooth surface essentially free of honeycombs, depressions, fins, holes, humps, dust, dirt, oils, and other surface contaminants is necessary to provide continuous support to the waterproofing material and good adhesion between the membrane and the substrate. Water pressure acting on unsupported material may cause it to extrude, deform and eventually rupture.
Good adhesion between the concrete surface and the waterproofing membrane is also essential to prevent water migration and leakage if there are any openings or imperfections in the membrane or concrete surface. Form coatings or release agents and concrete curing membranes could interfere with the development of good adhesion and should be removed before the waterproofing application.
The designer should specify proper substrate preparation in the concrete division of the specifications. Separate trades typically complete concrete placement and waterproofing application, and this situation can create confusion and problems. Areas of contention often centre on what is considered proper concrete preparation and whose responsibility it is to perform the repairs required for the waterproofing application.
The designer can eliminate these issues by providing language stating that concrete placement and repair be completed in accordance with ASTM D 5925. This is an excellent reference guide that contains a list of remediation measures for identifying and repairing fins, bug holes, form kick-outs and similar surfaces that are unsuitable for the application of waterproofing. Reference to this standard in the Concrete Section and Waterproofing Section will eliminate potential problems during the project. The designer should also require that the waterproofing contractor approve the surface in writing before installation.
Specific issues that must be addressed in the design specifications include concrete repair after form removal and removal and repair of any surface defects that occur during construction. Precast concrete is normally produced in a shop operation. Sharp offsets between precast sections should be corrected as indicated for new cast-in-place concrete. Surface defects, including tie holes, should be repaired immediately after the forms have been removed.
All honeycombed and defective concrete areas should be removed down to sound concrete. If chipping is necessary, the edges should be perpendicular to the surface or slightly undercut. No feathered edges should be permitted. The area to be patched and a surrounding band of approximately 6 inches should be dampened to prevent absorption of water from the patching mortar. A bonding grout or bond coat should be prepared using a mix of approximately one part cement to one part fine sand that is mixed to a consistency of thick cream. The mix should be evenly brushed into the surface.
Fins, protrusions or similar irregularities projecting from the concrete surface should be removed back to the surface by chipping, hammering or wire brushing. Care should be exercised to obtain a reasonably planar surface for the application of the waterproofing membrane system. Sharp offsets in the surface, such as those caused by formwork misalignment, should be mechanically abraded to provide gradual and smooth transitions between the offset surfaces. Some waterproofing systems do not require all concrete surfaces to be within the same plane as long as the transitions are gradual and smooth. The waterproofing manufacturer should be contacted for specific requirements in these cases.
Tie rod holes should be thoroughly cleaned out and dampened prior to complete fill with a proper patching material.
Some other benefits of waterproofing concrete.
- It prevents mould and mildew from getting into the walls and floor. This makes waterproofing essential to structural integrity and health.
- It reduces maintenance costs and clean-up. With waterproof structures, you have a lot less work to do when cleaning up after a heavy rainstorm or flood. Basic maintenance is much easier; the waterproof factor keeps things clean.
- Waterproofed walls and floors increase property value. When the time comes to sell, a waterproofed basement or sub-floor is a good selling point. No one wants to buy a house with water problems.
Things to do before waterproofing concrete:
- Make sure the surface is clean and dry. Use a scraper to remove old paint or wall/floor coverings. Sweep everything to ensure no dirt is hiding that you cannot see. If need be, use a warm water and soap mix to scrub walls or floors, making sure to rinse after you scrub. Allow drying thoroughly.
- Patch all holes with a hydraulic expanding concrete mix. Allow the patches to dry for a minimum of 24 hours.
- Tape off all items extending onto the floor or the walls like stairs or electric boxes.
Concrete Surface Preparation
An important step toward achieving adequate bond strength is to pay careful attention to the preparation of the surfaces that are to receive the waterproofing materials. Proper waterproofing performance depends on good surface preparation. The concrete surface must not be contaminated by chemicals that can have an adverse effect on the adhesion properties of the waterproofing membrane to the concrete surface. The surfaces must be newly exposed concrete that is free of loose, weak or unsound materials. Concrete surfaces should be generally dry; however, some waterproofing membrane manufacturers allow the placement of their materials over damp concrete surfaces.
The waterproofing manufacturer should be contacted for specific requirements in these cases. Care must be taken to prevent moisture from collecting at the interface between the concrete and the waterproofing membrane during curing. Before the application of the waterproofing membrane, testing should be completed to determine the adequacy of the surface preparation. The strength of the prepared concrete, as well as the ability of the membrane to adhere to the concrete, are two major items that must be checked before the project inception. The waterproofing manufacturers requirements and requirements of the American Concrete Institute and ASTM should be reviewed for recommended practices in these cases.
We have a huge range of waterproofing services Melbourne at Hitch Property Constructions that offers stress-free services for any water problem you got!
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 success of the waterproofing system will rely on proper concrete surface preparation. All concrete surface defects must be addressed acceptably prior to waterproofing application. As an architect, it is best to provide proper concrete surface guidelines 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 most difficult to design and highly litigated components of the building.