“Integral systems block the passage of water from both the positive and negative sides by working from within the concrete.”

Concrete by its very nature is porous. Any water absorbed into unprotected concrete can cause reinforcing steel corrosion and concrete spalling – Idevastating long-term effects to both the durability and structural integrity of a structure. The answer to designers, engineers and contractors perpetual headache is simple: keep the water out of the concrete. The solution is not as complicated as some may fear.

——————————————Gary Penk, Kryton International——————————————

There are three options. Concrete can be waterproofed from the positive (wet/exterior) side, negative (dry/ interior) side or from within the concrete itself (integral systems).     The oldest and most widely used method is positive-side waterproofing using sheet membranes but its failures and limitations are common and costly.     Integral systems block the passage of water from both the positive and negative sides by working from within the concrete. This technology, which dates back to the early 1900s, has undergone many improvements and developments over the last 30 years. It is now a highly effective, time-saving and cost-saving technology to use in place of traditional membrane systems.

Integral waterproofing

Integral crystalline waterproofing is most often a dry powder mix of Portland cement, fine silica sand and a specific (and usually proprietary) blend of chemicals. It is either an admixture added to ready-mixed concrete at the time of batching for in-situ pours or sprayed concrete applications, or a surface-applied mixture used for existing structures. Surface-applied crystalline waterproofing formulas are brushed or sprayed onto existing structures as a slurry coating or spread over and trowelled into freshly poured concrete slabs as a dry-shake treatment. 

When the blend of chemicals comes into contact with water, as it inevitably does, long narrow crystals grow within the concrete. These block the movement of water by filling the natural pores, capillaries and hairline cracks in concrete. Instead of forming a barrier on the positive or negative side of your concrete, they turn the concrete itself into a water harrier.     The advantages of this solution: 

Permanent solution – becomes a part of the concrete so it won’t wear away, crack, tear or peel – even against high hydrostatic pressure.

Perfect for blind-wall applications – can be added to the concrete or applied to the negative side of the structure (against water pressure). There is no need to save room outside the structure for membrane application.

Protects reinforcing steel – adds to the longevity of concrete structures by preventing the penetration of waterborne contaminants and chloride-laden liquids that cause the corrosion of reinforcing steel.

Saves weeks on construction schedule – can be applied to green concrete or added directly to the concrete. No need to wait for membrane application and backfilling can begin right away.

Two types of integral crystalline waterproofing

Close-up of Krystol grout, part of the Krystol KWS system being installed at five blocks high.Most integral waterproofing systems are compounds that either increase the density of the concrete or increase its ability to repel water. As these systems work to repel water, they are ‘hydrophobic’. Although hydrophobic systems may perform satisfactorily for damp-proofing, they can’t reliably resist liquid under hydrostatic pressure and have limited to no ability to reactivate and self-seal f u t w cracks and leaks. In contrast, hydrophilic systems actually use available water to grow crystals within the concrete – effectively shutting off pathways for moisture that can damage concrete.     Hydrophilic technology, such as Kryton International’s Krystol Waterproofing System, has distinct advantages over other crystalline products: 

penetrates deeper into concrete – many inches over time self-seals hairline cracks – minimum 0.5mm reactivates in the presence of moisture – even years later effective against hydrostatic pressure – up to 140m of head pressure impervious to physical damage and deterioration.

    Kryton’s Krystol line includes Krystol Internal Membrane (KIM), an admixture for new concrete. It also includes Krystol T1 and T2 surface-applied slurry system for existing concrete and Krystol Broadcast dry-shake system for concrete flatwork. Krystol systems have also been developed for repairing cracks, holes and water-proofing concrete construction joints, tie-holes and pipe penetrations.

BBA approved

KIM has received an Agrément Certificate from the British Board of Agrément stating that KIM provides watertight concrete, enhances concrete durability, improves protection against corrosion of reinforcing steel and is safe for use in potable water applications such as reservoirs, culverts and other similar structures. It was approved by the British Drinking Water Inspectorate to ensure the product does not contain or produce toxic materials that would make water unsafe for human consumption.

Environmental benefits Many traditional waterproofing methods use petroleum- based membranes or coatings on the concrete surface that require adhesives with highly volatile organic compounds. Oil from membranes can leach out and contaminate ground water. Vapour from the compounds can cause respiratory problems and contribute to ‘sick building syndrome’. However, hydrophilic and hydrophobic crystalline waterproofing is environmentally friendly. Crystalline waterproofing is a non-toxic, non-flammable, odourless product, and crystalline-treated concrete can also be recycled, unlike membrane-coated concrete.

London City Hall

Located on the south bank of the River Thames and next to Tower Bridge, London City Hall is a state-of-the-art building with a series of underground concrete tunnels and transformers room that were constructed using conventional membrane waterproofing systems. Leaks soon occurred through the concrete to allow room for service pipes, also leaked due to the high water pressure of the River Thames. In 2001, before City Hall opened, the Krystol concrete waterproofing system was chosen for repairing cracks, joints and

holes in concrete. It was applied from the inside against the water pressure to eliminate water entry. The drilled holes for the service pipes were filled with Krystol Bari-cote, followed by a slurry application of Krystol T1 and T2 to stop all water from entering the service rooms. By the time City Hall opened in 2002, the building was watertight.

Manchester

Manchester contractor Westshield chose KIM for its latest private residential development at Bowdon near Altrincham. The team needed a product that would be suitable for a below-grade structure that was to be built using the Amvic ICF (insulating concrete formwork) wall system and specifications outlined by the purchaser.    KIM was chosen to treat the concrete for the lift pit, car lift, ground floor slab (split pour), walls of the basement and the attached ground floor level swimming pool retaining structure. In total, around 170 cu m of KIM treated concrete was placed in conjunction with approximately 200m of Krystol Waterstop System.    Using Kryton in the basement meant that Westshield did not have to over-excavate the site in order to apply an external tanking membrane – they could take advantage of all the space available to them. In addition, once the ground floor was in place, they could backfill with confidence that their structure was 100% waterproof. Completion on the home is expected before the end of 2009. 

Protecting Structure............ Naturally!! Hydronil International is the branded manufacturer for cutting edge crystalline waterproofing systems, with a focus on a unique “Multiguard In-depth Crystalline Therapy” commonly referred to as “MICT”. The name of Hydronil is synonymous with watertight concrete!  Concrete structures treated with Hydronil’s MICT based products are healthier, more sound and resistant to corrosive chemicals including water and waterborne contaminants. In the end, what we get is a highly durable structure.What Hydronil is all about? Hydronil is about quality hydrophilic crystalline technologies that assure a watertight concrete. Treatments with Hydronil technologies begin as a surface applied slurry, dry shake, or as an admixture and work as a catalyst to create a reaction between un-hydrated cement particles and water within the concrete. This reaction over time creates billions of pin like crystals to fill the pores and capillaries. The process will continue as long as water and cement particles are present.

Multiguard In-depth Crystalline Therapy  (MICT)

Hydronil’s MICT concrete therapy is an excellent remediation procedure for revitalizing water-damaged concrete and to provide an effective protection against the deterioration of healthy concrete due to water ingress.

It is a physical treatment to the entire concrete structure to create a catalytic reaction within the concrete matrix resulting in a stronger, more durable and waterproof concrete. Hydronil´s therapy can be used as a preventative safeguard or as a cure. It will increase the durability of the concrete, autogenously heal micro cracking, and eliminate the need for any other waterproofing system. 

There is no need to allocate extra time for Multiguard In-depth Crystalline Therapy, hence projects are completed much in advance and there is a complete savings in waterproofing cost. As the Multiguard In-depth Crystalline Therapy occurs within the body of concrete, treatment can be done from negative or positive side of water pressure.

There is no need to provide extra space for application of MICT outside the structure, which ultimately saves excavation cost.

What Hydronil is all about?

Hydronil is about quality hydrophilic crystalline technologies that assure a watertight concrete. Treatments withHydronil technologies begin as surface applied slurry, dry shake, or as an admixture and work as a catalyst to create a reaction between un-hydrated cement particles and water within the concrete. This reaction over time creates billions of pin like crystals to fill the pores and capillaries. The process will continue as long as water and cement particles are present.

What is Multiguard In-depth System?

Multiguard In-depth System is a revolutionized protection system for concrete structures, concrete blocks and cement-sand rendered brickwork. It is a blend of special Portland cement, a group of active ingredients and surface treated quartz. The system is either applied by brush, spray, sprinkled or directly added into green concrete. Multiguard In-depth System thrives on moisture for migrating into the body of the concrete and generating billions of pin like crystals (see photo 1) sealing all capillaries and voids.

Other Benefits

Multiguard In-depth System offers many other benefits to concrete structures:

Waterproofing treatment makes concrete impermeable to full depth of structure.

 Enhances self-healing properties to hairline cracks up to 0.4 mm width.

Waterproofing characteristics are reactivated in presence of moisture-even many years later.

Hydronil treated structures can withstand hydrostatic pressure up to 170 metre (560 ft) of water head. With wide number of products manufactured by Hydronil, crystalline treatment scheme corrects flaws left out during concreting by showing path and location of the same. Being catalytic in nature, there is no product to get consumed, which ultimately makes system highly durable and long lasting. 

As the ingredients penetrate deep into concrete, Hydronil does not require any protection during backfilling or during placement of steel, wire mesh or any other material.

As Hydronil is active in moisture, application of coating does not require dry substrate.

It is an In-depth treatment to the body of the concrete, hence is no layer to get damaged, tear or pill off from the surface

There are many ways to benefit by treating concrete with Multiguard In-depth System and MICT.

Need of Waterproofing

CONCRETE

Contrary to common belief, concrete itself is a complex composite material. It has low strength when loaded in tension and hence it is common practice to reinforce concrete with steel, for improved tensile mechanical properties. Concrete structures such as bridges, buildings, elevated

highways, tunnels, parking garages, offshore oil platforms, piers and dam walls all contain reinforcing steel (rebar). The principal cause of degradation of steel reinforced structures is corrosion damage to the rebar embedded in the concrete.

POROSITY IN CONCRETE

When most of us think about concrete, we consider it to be an impenetrable barrier. What most of us don't realize, however, is that concrete is actually a very porous material by nature that will allow moisture to pass through it readily. Or we may call it ‘Hard Sponge’.

Imagine: Average pore size in concrete is 1,000 -10,000 nm where as the diameter of water molecule is only 0.28 nm! The average pore in concrete is at least 3,571.42 times larger than the diameter of a water molecule!

Typical Concrete Structure (Credit: Paul Stutzman, NIST)

Concrete’s porosity has a strong correlation with the water/cement ratio (W/C) but also depends on curing practice, the rheology characteristics of fresh concrete, the mix design etc.  It’s not only the pores percentage that counts but also pores sizes, pores distribution and the interconnections between the pores.  It’s logical to observe that concrete durability is closely linked to water intrusion and movement rates.  Furthermore, water inside concrete’s mass plays

the role of the carrier for harmful substances that can potentially have deleterious effects on the concrete and its steel reinforcements.

Water movement inside the concrete has to do with its permeability which is closely related to the total porosity and its distribution in the cementitious matrix of concrete. The building envelope when in contact with water, it absorbs varied degree of amount of water depending on its porosity.The mechanisms of water uptakes by building materials are as varies as the possible damages it causes to the building.

NEED OF WATERPROOFING

There are many reasons to waterproof concrete. They include health, cost effectiveness, structural integrity, reduced opportunity costs, usage purposes, visual appeal, and to increase the life of a concrete structure.

Here are some of the common problems associated with humidity and moisture ingress;

Humidity and moisture ingress often result in fungus and mold growth leading to itching, asthma, sneezing and a variety of health related problems.

Humidity and moisture ruin mortar, paint and drywall and result in costly repairs and unusable spaces.

Humidity and moisture can lead to the forced closure of hotels, restaurants, bars and impede revenue generation in many businesses.

Water ingress related problems can lower the value of houses, apartments and businesses. Humidity and moisture ingress increase maintenance costs and lower rentability of any

structures in which warehousing, housing people or housing animals is necessary. Humidity and Moisture can eventually lead to very expensive repairs or even

deterioration to the point in which a structure is rendered useless.

While the above listed humidity and moisture problems are commonly understood, what many fail to understand is how the long term costs and problems associated with water ingress into their structures can be prevented through effective waterproofing through crystalline technology.

A Leaking Basement

Water ingress is a major contributor to many of the concrete related problems that cause deterioration of concrete within concrete structures. These include corrosion, chlorides, carbonization, alkali-silicate reaction, freeze/thaw, and chemical attack.

1 Water Ingress and Corrosion The two most common causes of reinforcement corrosion are (i) localized breakdown of the passive film on the steel by chloride ions and (ii) general breakdown of passivity by neutralization of the concrete, predominantly by reaction with atmospheric carbon dioxide. Sound concrete is an ideal environment for steel but the increased use of deicing salts and the increased concentration of carbon dioxide in modern environments principally due to industrial pollution, has resulted in corrosion of the rebar becoming the primary cause of failure of this material. The scale of this problem has reached alarming proportions in various parts of the world.Corrosion deterioration in concrete normally occurs due to an electrical reaction caused by exposure of the reinforcing steel to oxygen and moisture. When the iron in the steel oxidizes, it expands, and causes tensile stress in the concrete until eventually the concrete cracks or spalls. As the cracks and spalls begin to occur increased amounts of water and oxygen access the reinforcing steel increasing the rate of corrosion and accelerating the deterioration effects. Stopping water ingress will also stop the effects of corrosion on the reinforcing steel thereby preventing tensile stress cracks and spalling.

2 Water Ingress and ChloridesIn 1962, it was reported that the required minimum concentration of chloride in the concrete immediately surrounding the steel to initiate corrosion, the chloride corrosion threshold, is 0.15% soluble chloride, by weight of cement. In typical bridge deck concrete with a cement factor of 7, this is equivalent to 0.025% soluble chloride, by weight of concrete, or 0.59 kg soluble chloride per cubic meter of concrete. Subsequent research at FHWA laboratories estimated the corrosion

threshold to be 0.033% total chloride, by weight of concrete.There are indications that the chloride corrosion threshold can vary between concrete in different bridges, depending on the type of cement and mix design used, which can vary the concentrations of tricalcium aluminate (C3A) and hydroxide ion (OH-) in the concrete. In fact, it has been suggested that because of the role that hydroxide ions play in protecting steel from corrosion, it is more appropriate to express corrosion threshold in terms of the ratio of chloride content to hydroxide content, [Cl-] / [OH-], which was recently established to be between 2.5 to 6.

When a concrete structure is often exposed to, salt splashes, salt spray, or seawater, chloride ions from these will slowly penetrate into the concrete, mostly through the pores in the hydrated cement paste. The chloride ions will eventually reach the steel and then accumulate to beyond a certain concentration level, at which the protective film is destroyed and the steel begins to corrode, when oxygen and moisture are present in the steel-concrete interface. Even high alkalinity will have minimal abilities to reduce deterioration. If water ingress is stopped even cast in chlorides will not deteriorate the concrete.

3 Water Ingress and CarbonizationCorrosion can also occur even in the absence of chloride ions. Carbonization is a chemical reaction between carbon dioxide in the air and the calcium hydroxide in the hydrated cement paste and with the presence of moisture reduces the pH of the concrete through the creation of carbonic acid. Over time this process will lower the pH as low as 8.5 of the concrete thereby permitting corrosion of the embedded  steel. By stopping water ingress the effects of carbonization can be dramatically reduced.

4 Water Ingress and Alkali-Silica Reaction/ Alkali Aggregate ReactionASR (Alkaline Silica Reaction) or AAR (Alkaline Aggregate Reaction) are basically a reaction that occurs when alkaline contaminated aggregates and moisture ingress cause an expanding gel  to form around the cast in aggregates in the concrete. The expansion of the aggregates causes cracking and spalling of the concrete and the entry of more moisture ingress. Stopping water ingress can stop the expansion process of the silicate reaction formed around the gel and prevent expansion of the gel formed around the aggregate thereby preventing cracking and spalling.

Multiguard In-depth Crystalline waterproofing is a very interesting and promising concept and it will surely draw more and more attention in the future as the relevant technology makes leaps.

Green Chemistry

Enjoyment of life, environmental protection and global fairness are the salient criteria of the Green Lifestyle. Hydronil’s MICT is a perfect fit for green chemistry.

Green chemistry encompasses the fundamentals of two significant trends: Healthiness and sustainability. All our products, technologies and activities are based on the principal of sustainable development, achieving a sensible balance between economics, ecological and social development without compromising the opportunity of future development.

As a global player, we are very much aware of our social responsibility and the respect that we owe both our employees and our neighbours.  Life, environment, company, products, the sustainability philosophy of Hydronil extents across all these aspects.

Concrete WaterproofingConcrete waterproofing is a process of making concrete surfaces, such as slabs, walls, floors, etc, water-resistant. Various methods and materials are used in this kind of waterproofing.Ads by GoogleWaterproof Your Terrace With Dr.Fixit Newcoat Register Now for a Free Check-Up! www.doctor-fixit.com/newcoat/index.aspxConcrete by itself is not waterproof in nature, it is porous. Water seepage through concrete may cause damage to the construction leading to money losses, besides other inconveniences. Thus, waterproofing the concrete is a must.

What is Concrete?It is a construction material composed of cement, water, aggregates, reinforcing materials, chemical and mineral admixtures. The aggregates include sand and gravel, while the reinforcing material is mostly the metal bars. Glass and plastic fibers can also be used as reinforcements. Chemical admixtures add special characteristics to the plain concrete. Mineral admixtures are added to the concrete to improve its strength. These can also be used as a replacement to Portland cement present in the concrete. Let us find more about the water proofing systems and related concepts.

Waterproofing SystemsThe two important systems in these are Integral Waterproofing System and the other that uses membranes. Hydrophilic system and hydrophobic system are the subtypes of the Integral Waterproofing System. Among different hydrophilic waterproofing systems, crystalline technology is the most popular one. In this method, the water present in concrete is converted into insoluble crystals. Some hydrophilic waterproofing products make use of a property called hydraulic swelling. Here, the waterproofing material swells as it absorbs water, eventually filling pore spaces present in the concrete. In the hydrophobic system, externally applied products viz. coatings, membranes, etc, are used as a protection against water.

MembranesWaterproofing membranes are either liquid or sheet membranes. The liquid membranes are sprayed on the concrete, forming a rubber-like coating about 60 mm thick on the concrete surface. Quick application and low pricing are its major advantages. The sheet membranes are prepared from asphalt. These membranes are laminated to polythene films and the sheets thus formed are then pasted onto the concrete. The sheets are consistent in thickness. Excellent waterproofing can be provided to foundation walls, parking lots, tunnels, etc, using these sheet membranes. As the sheets need to be manually pasted, it raises the labor cost which proves to be

its main disadvantage.

Hydrophobic ConcreteUnlike the hydrophobic membranes, 'hydrophobic concrete' is totally a different and innovative concept. Instead of applying any external agent for concrete waterproofing, here the concrete itself is manufactured waterproof. The concrete is made hydrophobic by adding admixtures to it at the time of production. These admixtures stop capillary action occurring in the concrete, thereby making it waterproof. This kind of concrete has been successfully used in Asia, Europe and Australia. It has also proved to be a boon for construction teams, since it allows construction to carry on even in the rains.

Crystalline WaterproofingLet's see how this technology can be used as an option to Integral Waterproofing System. First of all, the concrete which has to be waterproofed is saturated with water and then a low density solution is applied, followed by the crystalline waterproofing material, which is a high density solution. After this, the chemical diffusion process starts. The high density crystalline waterproofing solution seeps inside the concrete and travels towards the low density solution until an equilibrium is attained. Since water is applied to the concrete, cement hydration occurs. This hydrated cement now reacts with the crystalline material to form crystals inside the concrete. The diffusion process may take this crystalline waterproofing 12 inches inside the wall. This waterproofing is highly efficient, because crystals that are formed within the concrete remain protected from any kind of external damage. Resistance to 130 degree heat in a constant state is another advantage of this kind of waterproofing. It also resists chemical reactions like carbonation - which reduces alkalinity and damages the concrete. It stops chloride ion diffusion in the wall, protecting the steel present in the concrete from oxidation and also expansion.

Before You StartBefore one starts the waterproofing process, it is necessary to take into consideration some important points. The concrete surface should be clean. Any kind of debris, honeycombs, etc, should be removed. Rough surfaces should be smoothened, and holes need to be patched up. Check if the waterproofing material is compatible with the substance used for patchwork, so as to avoid any harmful chemical reactions. Some of the products used for waterproofing are flammable and due care should be taken while handling them.

Following these cautions will help in making waterproofing a safe activity, that will strengthen your house in the best way possible. Read more at Buzzle: http://www.buzzle.com/articles/concrete-waterproofing.html

Waterproof ConcreteGoing beyond surface treatments to reduce concrete permeability.

5 Waterproof Concrete

Water is essential to concrete production, placement, and curing. But once it fulfills its role in those processes, water is no longer concrete’s friend. Depending on its function and the nature of its exposure, concrete can of course perform well in wet environments. As a naturally porous material, though, and one that is prone to cracking, concrete is vulnerable to water infiltration. The unfortunate results can be freeze/thaw damage and deterioration due to corrosion of embedded steel reinforcement.

Any number of products and systems are available to help protect concrete structures from damage due to water, from coatings to sealers to membranes and more. Enormous amounts of effort and money are spent to design and apply such protection, with varying degrees of effectiveness.

One method that can simplify the protective process is to make concrete with admixtures that reduce its permeability—in effect to make the concrete itself waterproof. A variety of such admixtures are now on the market, and ACI Committee 212, Chemical Admixtures, offers some guidance on their use in its 2010 revision of ACI 212.3 “Report on Chemical Admixtures for Concrete.”

Chapter 15 of that report covers permeability-reducing admixtures (PRAs) and differentiates between those suitable for concrete exposed to nonhydrostatic conditions (PRAN) and concrete exposed to hydrostatic conditions (PRAH). Besides reducing permeability, some PRAs impart other beneficial characteristics, such as reduced drying shrinkage, reduced chloride-ion penetration, improved freeze/thaw resistance, and enhanced autogenous sealing.

6 Three types of PRAs

The materials used to produce PRAs vary, but they generally fall into three categories. The largest category consists of hydrophobic, or water-repellent, chemicals derived from soaps or

fatty acids, vegetable oils, and petroleum. These materials form a water-repellent layer along pores in the concrete, but the pores themselves remain open.

The second category is finely divided solids—either inert or chemically active fillers such as talc, clay, siliceous powders, hydrocarbon resins, and coal-tar pitches. These materials densify the concrete and physically limit the passage of water through the pores. Some experts also consider supplementary cementitious materials (SCMs) to be in this category.

The third category consists of crystalline products—proprietary active chemicals in a carrier of cement and sand. These are hydrophilic materials that increase the density of calcium silicate hydrate or generate crystalline deposits that block concrete pores to resist water penetration. The various types of materials can be used alone or in combination to give different levels of performance.

According to the ACI report, concrete produced with hydrophobic chemical admixtures could theoretically resist some hydrostatic pressure. However, because the hydrophobic material does not uniformly coat all pores and because the concrete also contains larger voids, such products are not typically classified as PRAHs.

There are also some latex-polymer admixtures that can resist hydrostatic pressure, but they can’t bridge cracks in concrete and thus don’t produce truly watertight concrete structures. These admixtures are sometimes added to repair mortars, but are not typically used in ready-mixed concrete.

It is the hydrophilic crystalline admixtures that provide concrete with the greatest resistance to infiltration of water under hydrostatic pressure. Their active ingredients react with water and cement particles to form calcium silicate crystals that integrally bond with the cement paste. These crystalline deposits block both pores and micro cracks in the concrete, to prevent the

passage of water. This reaction continues over the life of the concrete, serving to seal not only initial shrinkage cracks, but also cracks that occur over time.

Table 1, reproduced from ACI 212.3, summarizes results from a series of permeability tests performed on concrete mixes with and without three different types of PRAs. Note that these results only indicate the reduction in permeability between the reference and test concrete for each admix type. They can’t be used to directly compare the different admix technologies because the reference concrete mix for each type was different.

When to use them

In theory, a PRA could be added to any concrete mix without adverse effects, but it’s not usually necessary in practice. The value of a PRA depends entirely on the environment the concrete will be exposed to and the importance of keeping water from passing through. For interior columns, beams, and floor slabs in a high-rise, permeability isn’t a big issue. On the other hand, for structures that will be exposed to moisture, salt or salt water, wicking, or water under hydrostatic pressure, using a PRA can help prevent problems such as water migration, leaks, freeze/thaw damage, corrosion, carbonation, and efflorescence.

PRANs are often used in architectural concrete, precast panels, and concrete brick, block, and pavers to repel rain and minimize dampness. Reducing permeability can help minimize efflorescence and make it easier to keep walls clean.

PRAHs are needed for more extreme and continuous exposures, such as below-grade structures, tunnels and subways, water tanks and pools, bridges, and dams. Manufacturers of the crystalline PRAHs say the products can eliminate the need for membrane waterproofing systems and epoxy-coated reinforcement, thereby reducing the cost of waterproofing.

How to use them

Like other admixtures, PRAs are typically specified by the architect or engineer and added to the concrete at the ready-mix plant. Greg Maugeri, head of New England Dry Concrete, which distributes Kryton’s line of PRAHs in the northeastern U.S., describes the process: “We market to ready-mix companies, but part of our role is to educate designers and applicators about the product. We’ll help designers understand how to detail waterstops when they use our product, because that’s different from conventional membrane waterproofing.”

“Besides reducing permeability, the admixture acts as a mild retarder, so it helps to control the heat of hydration and consequently reduces shrinkage cracking. It doesn’t drastically change the properties of fresh concrete, but it can improve workability somewhat. When someone considers using our product, we’ll review the mix design and also send it to Kryton’s lab for review, to make sure any interactions with other admixtures are taken into account. We also recommend that the contractor do a test pour, to check for air content, slump, and so on,” Maugeri says.

“The typical dosage rate for crystalline PRAHs is 2% by weight of total cementitious materials,” says John Ladas, a sales representative for Xypex Chemical Corp.’s waterproofing admixtures,

“except in an extraordinary case, such as an exceptionally corrosive atmosphere. We can also modify the formula depending on the circumstances. We make one formulation that doesn’t retard set at all. We might recommend that for large flatwork areas, cold weather, or a mix that contains a lot of slag.”

Successful projects

Waterproofing admix was used in the renovation and expansion of the Mark Jefferson Science Complex at Eastern Michigan University in Ypsilanti, completed earlier this year. Concrete containing the Xypex crystalline PRAH was used for green roof slabs on the building addition and for an underground utility tunnel. It was the first experience with the material for Jennifer Emerick, project manager for general contractor The Christman Co. in Lansing, Mich., and she was favorably impressed. “The tunnel consists of a 1-foot, 2-inch-thick slab, with 1-foot-thick walls and lid. It was built about 2 years ago, and there have been no leaks since the initial shrinkage cracks were sealed by the crystallization of the admix. It worked just the way the manufacturer said it would. We also got a watertight roof on the addition, without any additional roofing materials. And the placement went smoothly, just like any concrete mix,” Emerick says.

For projects and applications that need waterproof concrete, the use of PRAs is worth considering. Contractors need only follow sound placement and finishing practices to install it successfully, and owners may be able to cover the costs by saving the labor and materials required for other waterproofing methods.

 

7 ACI International Report Examines Waterproofing Admixtures for Concrete: Crystalline vs. Pore Blocking and Other Admixtures   Other News  Subscribe to newsletter   Feb 10, 2013

This report examines three classes of admixtures that all reduce, in some way, the permeability of concrete. The classes are hydrophobic or water-repellent chemicals, mineral fillers, and crystalline materials. In addition, the report defines two sub-categories for admixtures intended to reduce water ingress as either a PRAN – for concrete not subject to hydrostatic pressure, or as a PRAH – for concrete that is subject to hydrostatic pressure.

The water repellent or hydrophobic admixtures are based mostly on fatty acid derivatives called stearates which react with calcium hydroxide in the pore water to form an insoluble stearate that

lines the pore walls. Waxes and oily emulsions can also be used as a base for hydrophobic admixtures but they are non-reactive. These types of admixtures are effective in reducing the absorption and ingress of chlorides into concrete but usually only under non-hydrostatic conditions and thus are usually classified by this document as PRANs.

The mineral fillers are inert finely ground minerals such as talcs, bentonites, clays etc but can also include chemically active materials such as lime and alkaline silicate based products. Some experts include SCMs in this category as well. While these materials will often densify the matrix and possibly shrink the pores of the concrete and restrict water passage, they typically do not fully block all pores and as such are also classified as PRANs.

Crystalline-based admixtures, on the other hand, are hydrophilic in nature and react with the constituents of the cement matrix to form CSH crystals. These crystals generate pore blocking deposits that are found to improve the concrete’s ability to resist water penetration under pressure. These admixtures have been found to remain chemically active within the concrete and will seal additional gaps up to a certain size as they occur.

The ACI 212.3R document recommends PRAH type admixtures for applications that will experience hydrostatic head such as below grade and water retaining structures. The ACI 212.3R document further recommends that the water pressure resisting capabilities of the admixture modified concrete should be checked and confirmed through the use of permeability tests such as the US Corp of Engineers C48, DIN 1048 or BS EN 12390. The results of these tests can be used to determine a permeability coefficient K, or side by side testing against a control can be used to give an indication of permeability reduction.

Xypex Admix products would be classified as PRAH and have excellent crack healing properties. As such, Xypex admixtures are ideally suited for concrete that will need to perform in the most severe waterproofing applications. Furthermore, Xypex-treated concrete improves many of the other engineering properties of concrete such as its freeze and thaw resistance, corrosion resistance, chemical resistance and carbonation resistance.

Many of Xypex’s competitors have for years suggested that their active or inert pore blocking technology will give performance similar to Xypex, but this recently released document from ACI suggests otherwise. The latest copy of the ACI 212-3R-10 is available on-line from ACI International and is suggested reading for those in the concrete industry.

Xypex introduced Xypex Crystalline Technology some 40 years ago and has become a primary resource to the concrete industry for information regarding crystalline waterproofing.

About Xypex Chemical Corporation

Xypex is a non-toxic, chemical treatment for the waterproofing and protection of concrete. Xypex's primary and most distinguishing performance feature is its unique ability to generate a non-soluble crystalline formation deep within the pores and capillary tracts of the concrete - a crystalline structure that permanently seals the concrete against the penetration of water and other liquids from any direction. Xypex crystalline products are dry powder compounds composed of portland cement, silica sand and many active, proprietary chemicals.

The ABCs of Integral Crystalline Waterproofing

Although crystalline waterproofing technology has been around for more than 50 years, it is still considered “state-of-the-art” and has only recently been embraced by the construction industry as a superior replacement for conventional membranes. Used in virtually every country around the world, integral crytalline waterproofing has been repeatedly and successfully tested.

Though concrete looks like a dense, rock-hard material, it’s actually full of pores, capillaries and microcracks invisible to the naked eye. It’s through these openings that water can enter and cause damage, making waterproofing necessary. Traditional membranes only cover the outside of

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concrete whereas crystalline chemicals actually work deep below the surface, within the concrete matrix itself.

The revolutionary technology of integral crystalline waterproofing is changing the way concrete structures around the world are protected from corrosion and water damage. When crystalline chemicals come into contact with water, a catalytic reaction occurs that produces crytals that plug the natural pores and microscopic voids of concrete. Crystalline technology waterproofs concrete by forming long hexagonal prisms that block concrete’s pores and transform the concrete itself into a strong, durable waterproof barrier.A Better Choice All Round

Unique Self-Sealing Ability

One of the unique traits of an integral crystalline waterproofing application is its ability to "self-seal". Only a small fraction of the chemicals are used to facilitate crystal growth when they are initially mixed or applied to concrete. The unused chemicals sit dormant. When future cracks occur, water acts as a catalyst to the crystalline chemicals, triggering additional crystal growth to seal the crack.

A Permanent and Sustainable Choice

Integral crystalline waterproofing is a permanent solution - it will not crack, peel, tear or wear away, even against high hydrostatic pressure, so it never needs replacing. It's non toxic, safe for potable water tanks and contains no volatile organic compounds. In comparison, external membranes are usually petroleum-based and can leach oil into the ground, contaminating drinking water. Membrane-coated concrete also goes straight to the landfill while crytalline waterproofed concrete can be safely recycle.

Easy Application

Crystalline chemicals come in powder form and can be conveniently added to new concrete at the time of batching or at the jobsite to create a powerful water barrier in slabs, walls and joints. There is no need for any type of surface application at the construction site.

Crystalline formulas can also be brushed or sprayed onto existing concrete in slurry form or broadcast onto fresh concrete flatwork by way of the "dry-shake" method. Products and application methods also exist for crack repair, construction joints, pipe penetrations and form-tie holes to protect against contamination and steel reinforcement corrosion. The best waterproofing systems can be applied to the positive or negative side of concrete, allowing the structure to be waterproofed or repaired without the costly process of digging up the perimeter landscaping.

When applied to existing concrete, crystalline chemicals are absorbed by natural capillary action and diffusion. Once inside, the chemicals begin growing crytals that fill the naturally occurring pores, capillaries and microscopic voids of concrete.

Time and Cost Savings

Using crystalline systems can actually accelerate project schedules by eliminating the need for conventional membrane application. Backfilling can begin right away and the cost of labor and surface membrane materials are reduced.

Reliability

Crystalline technology is impervious to physical damage or detorioration. While membranes are the best the day they are applied, crystalline waterproofing becomes better with time.

Crytalline Copycats - What's the Difference?

Kryton's flagship product is Krystol Internal Membranes, better known as KIM. KIM is an environmentally friendly admixture that is mixed directly into the concrete. It can be thrown into a ready-mix truck in a convenient dissolvable bag.

KIM is also the world's first and leading crystalline waterproofing admixture. Being 'the original' means there are plenty of copycats on the market. It's easy to confuse crystalline waterproofing with products that are simply concrete densifiers or pore blockers. It's

important to stay away from stearates and sodium silicates and beware of hydrophobic products.

There are many crystalline products that claim permanent, in-depth waterproofing. However, the majority of these contain stearates and sodium silicates. Stearates and sodium silicates are often classified as dampproofers and not waterproofers since they are known to break down and leach out of concrete.

Silicate-based products react with compounds in concrete such as calcium hydroxide or free lime. The reaction binds the compounds into an insoluble solid and does not panetrate more than a few milimeters into the concrete. These products do not possess self- sealing capabilities and since they are insoluble, the presence of water in the future has no effect on them.

Stearate-based products are also hydrophobic, which means they repel water. These products have minimal penetrating ability and merely fill the initial surface pores of concrete. They are best when first applied and will not withstand hydrostatic pressure over time and cannot effectively provide long-term waterproofing.

Stick to the original: KIM

Kryton's KIM is a cementitious chemical admixture that contains no stearates, sodiums silicates or harmful chlorides. KIM works through a proprietary blend of chemicals, promoting crystal growth that counteracts water intrusion. Moreover, KIM and other Krystol products are hydrophilic - they use water to facilitate a chemical reaction that creates an impermeable concrete mass. More water equals more crystals, until no additional water can panetrate. KIM's self-sealing hydrophilic properties mean it's able to grow throughout the concrete, increasing resistance to hydrostatic pressure and allowing it to become stronger with age.

In short, KIM works. It is a true crystalline waterproofing admixture that has become the industry standard for new construction. Guaranteed.

The world's leading It's never too late to A new phase in

Krystolize

concrete or

waterstop technology for concrete

8 The Science of Krystol® Technology

Krystol® technology is based on principles that are very similar to the processes that occur during the hydration and hardening of concrete. Cement is mainly made up of several calcium silicates. When cement particles are mixed with water, a chemical reaction occurs whereby these calcium silicates combine with the water to form new compounds. The new compounds are calcium silicate hydrate (CSH) and calcium hydroxide.

Building "green' is increasingly becoming a necessary part of a construction firm's best practices. Instead of just being a niche sector, green building is now at the forefront of design and construction.

The rigorous LEED (Leadership in Energy and Environmental Design) Green Building Rating System is rapidly becoming the standard for measuring a building's environmental performance. Only introduced in the US in 2000 and in Canada in 2004, LEED standards are encouraging the construction industry to create buildings that are environmentally responsible, healthy, and profitable. Governments at all levels across the US and Canada are imposing regulatory requirements to ensure new public buildings meet a certain LEED standard.

Green concreteWith growing global pressure to go green, more eco-friendly products are being developed. "Green concrete" used to refer solely to concrete that had set but not hardened. Today, it also means concrete that's made with recycled alternative materials such as reclaimed fly ash: a by-product of coal burned at power plants. Usually trucked off to landfills, the tiny glass particles of fly ash are now being used in place of traditional Portland cement to make concrete. Not only does adding fly ash increase concrete's strength and durability, but this substitution reduces the greenhouse gas footprint of concrete.

Another green innovation is a new concrete recipe spiked with titanium dioxide: a compound often used in sunscreen products. This new cement becomes chemically active in sunlight and neutralizes air pollutants such as benzene, carbon monoxide, nitrogen oxide, and others.

Finally, there is pervious concrete. Originally used a century ago in Europe as structural insulation, pervious concrete is a permeable, porous material. This environmentally friendly material is now making a resurgence in places such as parking lots, because it allows storm and nuisance water to filtrate into the ground, recharging ground water, and resulting in zero discharge of polluted runoff into waterways. This in turn reduces urban flooding, improves the health of adjacent trees, and reduces or eliminates the need for storm drain infrastructure.

However, more often in buildings and construction, it's waterproof concrete that's needed. Increasingly, in the new LEED-based paradigm, the old methods of waterproofing concrete with oil-based membrane sheets are just not environmentally acceptable.

Environmentally responsible waterproof concreteWhile concrete on its own has huge advantages as a green building material, making it waterproof using old-fashioned, externally applied membranes is less acceptable in today's eco-conscious environment.