Concrete durability (the life of the concrete) is always subject to a variety of variables. These variables include not only the mix design, the compressive strength, and the waterproofing technology used, but include all phases from designing the structure correctly to placing and finishing properly. As is only logical, from conception to the finishing of the structure, all parties involved should be working towards a concrete that will last the life of the structure. Keep in mind that a structure that is to last 20 years will have different needs and costs than a structure that is to last 100 years. Although Krystaline Technology can dramatically enhance concrete´s durability, it does not eliminate the responsibility of insuring that all phases from inception to termination are conducted properly.
In understanding clearly how crystalline technology will work effectively for the life of the concrete, it is important to clarify the following definitions:
- Catalyst –A substance, usually used in small amounts relative to the reactants, that modifies and increases the rate of a reaction without being consumed in the process.
- Catalysis –is the process in which the rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst.
- Adsorption –is the adhesion of molecules of gas, liquid, or dissolved solids to a surface.
The main function of Krystaline Technology is to further enhance the hydration of concrete, through the combined processes of catalysis and adsorption, until concrete becomes waterproof.
To explain the catalytic nature of true crystalline technology we must first understand a few concrete basics. The following is a very simplified version focussing only on how it relates to crystalline growth. As is common knowledge the binders in concrete are primarily as follows:
When water is added to cement, each of the compounds undergoes hydration and contributes to the final concrete product. The tri-calcium silicate (which contributes to initial strength) and dicalcium silicate (which reacts more slowly than the tricalcium silicate and contributes only to the strength at later times) begins a reaction when water is added to concrete eventually leading to the formation of calcium silicate hydrate crystals within the concrete.
Crystalline assists unhydrated tricalcium silicate and dicalcium silicate to form millions of thicker and longer calcium silicate hydrate crystals to fill the pores and capillaries. This technology uses adsorption (not to be confused with absorption) and attaches itself to the calcium silicate hydrates that occur during the reaction between water and tricalcium silicate and dicalcium silicate. As the calcium silicate hydrate grows and moves deeper into the concrete, the crystalline attached to the calcium silicate hydrate also moves further into the concrete. Since the product is catalytic in nature it is never used up and will always be present.
What does this mean to Concrete
The use of crystalline technology results in concrete that is waterproof for the life of the concrete. There are both short term and long term benefits to using crystalline technology within concrete.
Short term benefits include the following advantages:
- Crystalline technology will lowers the heat of hydration resulting in a reduction of drying shrinkage cracks and thermal dilation cracks.
- Crystalline technology increases concrete´s compressive strength resulting in stronger more durable concrete.
- Crystalline technology increases air entrainment in the concrete resulting in increased resistance to freeze/thaw cycle damage and surface scaling.
- Crystalline technology increases wet concretes slump while insuring improved consolidation and consistency.
- Crystalline technology can be used easily with other forms of protection
The long term benefits of Krystaline Technology are the greatest area of advantage. Besides providing the short term benefits and solving the obvious problems of water pooling in your structure, it allows long term performance in areas that are long term problems for most other technologies such as chloride ion penetration and carbonization.
As is commonly understood, refined metals such as reinforcing steel have a tendency to corrode. The contributing factors to the corrosion of reinforcing steel are the composition, grain structure, presence of entrained stress from fabrication and the environment in which it is placed including availability of water, oxygen, ionic species, pH and temperature.
In concrete the abundance of calcium hydroxide and the small amounts of sodium and potassium give concrete a very high pH of usually 12 to 13. In the early stages of the concrete, the high alkalinity of the concrete reacts with the surface layer of embedded reinforcing steel to create a film around the reinforcing steel. This film protects the steel from corrosion.
Chloride ions (from de-icing salts, sea water, contaminated ground water, etc.) are carried into the concrete by water and penetrate slowly through the pores and capillaries in the concrete eventually reaching the reinforcing steel. As the concentration level of chloride ions increases, the protective film created by the high pH will be destroyed. The destruction of the protective film and the presence of moisture result in corrosion of the reinforcing steel.
Carbonization refers to the deterioration of the concrete through the process of air entering the concrete, dissolving in moisture and reacting with hydroxides to create carbonates. The result is a lowering of the pH value of the concrete. Lower pH values (less than 9.5 or 10 depending which expert you follow) result in the deterioration of the protective film around the reinforcing steel reducing the resistance to corrosion and eventually leading to the deterioration of the reinforcing steel.
The effects of carbonization are further compounded when the concrete is subject to waterborne contaminants and chloride ion penetration. The Portland Cement Associationstates
“Carbonation of concrete also lowers the amount of chloride ions needed to promote corrosion. In new concrete with a pH of 12 to 13, about 7.000 to 8.000 ppm of chlorides are required to start corrosion of embedded steel. If, however, the pH is lowered to a range of 10 to 11, the chloride threshold for corrosion is significantly lower – at or below 100 ppm.”
Stopping water ingress into the concrete is the obvious solution to reducing carbonization and chloride ion corrosion of reinforcing steel. If the moisture is stopped the carbonization process and the ability of chloride ion penetration in the concrete is arrested. The protective film around the reinforcing steel is maintained together with the concrete´s pH value while stopping the cathodic reactions and reducing the electrical conductivity of the concrete. Crystalline technology has the further advantage of being part of the concrete and is never used up. The ability to stop water and the problems associated with carbonization and chloride ion penetration (as well as other types of waterborne contamination) is always present and ready to reactivate upon the presence of moisture.
“Autogenous Healing” is the term used to describe the natural occurring process in which concrete, in the presence of moisture, can self-repair cracks.
There are many variables involved in the determination of autogenous healing in regards to width of cracks and time. Test conditions seem to vary and it seems that every test achieves differing overall results. As published by The Concrete Society both BS 8007, the design of concrete structures for retaining aqueous liquids, and the Water Services Association’s Specification, it is implied that cracks up to 0.2 mm wide will autogenously seal within 28 days; cracks up to 0.1 mm will seal within 14 days. Keep in mind that the time (and even the ability to actually autogenously heal the cracks) may vary subject to how the cracks are caused, applications of tension, static water or flowing water, variations in hydrostatic pressure, fresh water or salt water, the thickness of the structure, the shape or form of the crack, the depth of the crack and the external conditions surrounding the crack. One must consider that every factor surrounding the crack, and the concrete will impact positively or negatively the performance of the concrete to autogenously heal.
Crystalline technology, both surface and admix applications, work as a catalyst between the unhydrated cement particles in the concrete and any moisture that may be present (or become present in the future) causing the concrete to further hydrate. The hydration promoted by the catalytic reaction is enhanced, resulting in additional and enhanced calcium silicate hydrate crystals within the concrete, filling the pores, capillaries and micro-cracks within the concrete. The catalytic nature of the technology results in an ability to be constantly present within the concrete even decades later.
An enhanced hydration results in an enhanced ability to autogenously heal concrete. Krystaline Technology enhances the hydration process there by enhancing the autogenous healing process within the concrete.
Factors To Consider
- There is always an abundance of unhydrated tricalcium silicate, dicalcium silicate particles and calcium silicate hydrate in concrete even decades after the concrete has been placed.
- Once crystalline technology has been introduced into the concrete it is always present.
- The catalytic nature of the product (unlike reactive products) insures that it is never depleted
- The only material necessary for continued activation even, decades later, of the crystalline process is the presence of moisture or water.
- The reaction will continue as long as moisture is present.
- Since crystalline technology enhances the hydration process, it also enhances concrete´s natural abilities such as increased compressive strength and self-healing capabilities.
- The waterproofing capabilities will last for the life of the concrete.