Comparison of Concrete Hardeners, Concrete Densifiers

·     Comparison of CONCRETE HARDENERS/DENSIFIERS

·      Sodium (N) Potassium (K) Lithium (Li) Silicates and Nano- Silica

·       Sodium (N) Potassium (K) Lithium (Li) Silicates

·       Developed in the 1930s (N&K) and late 1990s (Li)

·       Used to penetrate and harden concrete

·       Largest molecular ion size prevents deep penetration providing deepest (4-5 mm)

·       Varying degrees of reactive “Sites” provide low to moderate chemical reaction and bonding time

·       Water soluble (N&K) causes expansion/contraction in Wet/Dry cycles. Li is insoluble and remains stable

·       Very corrosive, increases the pH of the concrete to (pH 11-13)

·       Not good for sealing concrete

·       Generates corrosive, gelatinous slurry that must be scrubbed away and disposed of as hazardous waste

·       Requires continuous stirring and scrubbing to create any reaction with concrete.

·       May contribute to sweating and white deposits (N&K)

·       Requires dwell time

 

·        Nano-Silica Concentrated dispersion of Nano-silica in water

·        Developed in the 2000s                                          

·        Penetrates and hardens concrete to increase abrasion resistance. Up to double the abrasion resistance compared to silicates.

·        Minimum molecular ion size 5-30nm) provides deepest penetration depth (6.4 mm)

·        Highest concentration of reactive “sites” on nano-silica molecule provides the most efficient (fastest) chemical reaction and bonding

·        Water insoluble; remains stable under volatile climatic conditions

·        Non-corrosive (up to 1000 times less corrosive) and inert, maintains a neutral pH balance (pH7-9)

·        Can be used to seal concrete

·        Does not produce excess mineral salts or white deposits even if over-applied. No need to scrub or discard

·        Spray-on application no ongoing agitation, scrubbing or rewetting required; reacts to concrete immediately upon contact

·        Does not contribute to sweating or white deposits

·        Not dependent on dwell times