Lithium Silicate Chemistry
Around World War II, many chemical companies began making sodium and potassium silicate products to harden and protect the surface of concrete.
The Chemistry
Sodium and Potassium Silicates:
Silicates and siliconates have one silicon (carbon) atom bonded with 3 or 4 oxygen atoms. The higher alkalinity of the sodium and potassium silicates causes a fast, violent reaction with the available free calcium in the concrete, leaving clumps of unreacted calcium hydroxides behind that will absorb moisture.
Lithium Silicate (Quartz-Lithium™ Technology):
Compared to sodium and potassium silicates, Lithium has lower alkalinity and lower viscosity. This makes the reaction in concrete slower and more even. When lithium reacts with the free calcium in concrete, it forms insoluble tricalcium silicate structures that are stronger and more stable, and keeps moisture out of the concrete better than sodium and potassium silicates. The lower alkalinity makes the concrete less likely to effloresce. The lower viscosity also means the penetration is better.
Alkali-Silica Reactivity (ASR):
Alkali-Silica Reactivity is a world-wide problem that causes cracks and microcracks in concrete. It occurs when reactive, high-alkali aggregate, silica, and water combine to form concrete. The resulting reaction forms an expansive gel that fractures concrete. Sodium and potassium silicates are higher in alkalinity and may contribute to ASR at the surface. Lithium-silicates fight ASR in three ways: 1) keeping moisture out, 2) reducing alkalinity, and 3) introducing lithium into the reaction, which can calm and even stop the ASR reaction. For subsurface ASR, we recommend using a lithium nitrate product followed by an application of lithium silicate.
Crenz Protect:
Salt intrusion into concrete is likely to be problem in parking decks, bridges, loading docks, and marine facilities. Crenz Concrete has developed Crenz Protect to fight this problem. This lithium silicate-based product combines the excellent hardening and dust proofing characteristics of a densifier with the superior salt protection properties of a silane. Crenz Protect keeps out at least 91% of all chloride over a specified period of time.
Compared to coatings and silanes, Crenz Protect has the following advantages:
♢ Penetrates a few mm, so it won’t peel or wear off.
♢ Impervious to UV exposure
♢ Easy application water-based and non-hazardous
♢ Shorter cure time
♢ Lower cost