Multiguard In-depth Crystalline technology for waterproofing provides a reliable solution to protect concrete and reinforcing steel from water ingress, enhancing the durability of structures. Contrary to common belief, concrete itself is a complex composite material. It has low strength when loaded in tension, which is why it is common practice to reinforce concrete with steel for improved tensile 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 in steel-reinforced structures is corrosion damage to the embedded rebar.
When most of us think about concrete, we consider it to be an impenetrable barrier. What many don’t realize, however, is that concrete is inherently porous and allows moisture to pass through readily — almost like a ‘Hard Sponge.’
Imagine: The average pore size in concrete is 1,000–10,000 nm, whereas a water molecule is only 0.28 nm! This means the average pore is at least 3,571 times larger than a water molecule.
Concrete’s porosity depends on the water/cement ratio (W/C), curing practice, rheological properties of fresh concrete, mix design, and more. It’s not just the percentage of pores that matters, but also their sizes, distribution, and interconnections. Concrete durability is closely linked to water intrusion and movement, which also carry harmful substances that can damage both concrete and embedded steel.
Water movement inside concrete relates directly to permeability, which is influenced by total porosity and its distribution in the cementitious matrix. This is where Multiguard In-depth Crystalline technology for waterproofing comes into play, providing advanced in-depth waterproofing by penetrating and sealing concrete pores to enhance durability and resistance against water ingress.
There are many reasons to waterproof concrete, including health, cost-effectiveness, structural integrity, reduced opportunity costs, usage purposes, visual appeal, and extending the life of a concrete structure.
Some common problems associated with humidity and moisture ingress include:
Fungus and mold growth, leading to itching, asthma, sneezing, and other health issues.
Damage to mortar, paint, and drywall, resulting in costly repairs and unusable spaces.
Forced closure of hotels, restaurants, and bars, impacting revenue generation.
Lowered property value for houses, apartments, and commercial buildings.
Increased maintenance costs and reduced rentability for warehousing, housing, or animal shelters.
Expensive repairs or even structural deterioration that can render a building unusable.
While the above-listed problems are commonly understood, many fail to realize that long-term costs and structural damage from water ingress can be effectively prevented through advanced crystalline technology. By using concrete protection crystalline waterproofing, water penetration is minimized, ensuring enhanced durability, reduced maintenance, and superior protection for any structure.
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.
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 due to neutralization of the concrete, predominantly from reaction with atmospheric carbon dioxide. Sound concrete provides an ideal environment for steel; however, the increased use of de-icing salts and higher concentrations of carbon dioxide in modern environments, largely due to industrial pollution, have made corrosion of rebar a primary cause of concrete failure worldwide.
Corrosion in concrete typically occurs through an electrical reaction when the reinforcing steel is exposed to oxygen and moisture. As the iron in the steel oxidizes, it expands, creating tensile stress in the concrete until cracking or spalling occurs. Once cracks and spalls form, more water and oxygen reach the reinforcing steel, accelerating corrosion and deterioration. Implementing effective reinforcement corrosion protection by stopping water ingress can prevent tensile stress cracks and spalling, significantly enhancing the durability of concrete structures.
In 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.
Corrosion can also occur even in the absence of chloride ions. Carbonation is a chemical reaction between carbon dioxide in the air and the calcium hydroxide in hydrated cement paste. In the presence of moisture, this reaction reduces the pH of the concrete by forming carbonic acid. Over time, the pH can drop as low as 8.5, allowing corrosion of the embedded steel. Using an effective corrosion protection coating to stop water ingress can dramatically reduce the effects of carbonation and help preserve the durability of concrete structures.
ASR (Alkali-Silica Reaction) or AAR (Alkali-Aggregate Reaction) occurs when alkaline-contaminated aggregates and moisture ingress form an expanding gel around the aggregates in concrete. The expansion of these aggregates leads to cracking and spalling, allowing more moisture to penetrate. Stopping water ingress can halt the expansion of the silicate gel and prevent further cracking and spalling.
Multiguard In-depth Crystalline technology for waterproofing offers a very promising solution, providing effective crystalline waterproofing in concrete that protects structures, mitigates moisture-related damage, and enhances long-term durability.