Aesthetic Damage
Internal - External
- Efflorescence
- Paint Peel Off/ Blisters
- Fungus
- Mold (Mildew)
- Dirt Pick Up
Structural Damage Due to Water Seepage
Cement loses its strength due to:- ASR (Alkaline Silica Reaction)
- Freezing/ Thawing
- Carbonation/Acid Rain/Sulphate
Corrosion of Reinforced Steel Bars
Leading to Loss of Ductility and Strength
Alkali-Silica Reaction
[OH-]
=Si-O-Si= + H2O ------------> =Si-OH…….OH-Si=
Carbonation Reaction
H2O + CO2 -----> H2CO3
Carbonic Acid
Ca(OH)2 + H2CO3 --> CaCO3 + 2H2O
Calcium Hydroxide Calcium Carbonate
Acid Rain
S + nO2 -----> SOx (Sulfur Oxides)
SOx + H2O ----> H2SO4 + H2SO3 + ….
Strong Acids
N2 + O2 ---- NOx (Nitrogen Oxides)
NOx + H2O ----- HNO3 + HNO2 + ....
Strong Acids
Ca(OH)2 + H2SO4 ---- CaSO4 + 2H2O
Ca(OH)2 + 2HNO3 ---- Ca(NO3)2 + 2H2O
Damage due to capillary rise
Crystalline Technology
Sodium Silicate is sold commercially different brand name, that include,Zypex, Accura 2000, DOW 771,
Sodium Silicate [Na2SiO3] water solution pH 12+
Chemistry of Crystallization
Na2SiO3 + Ca(OH)2 ---> CaSiO3 + 2 NaOH
Calcium Hydroxide Calcium Silicate Sodium Crystal Gel Hydroxide
- This chemistry works effectively only for the new concrete. Product is less effective
for the Old concrete since Ca(OH)2 distribution is not uniform. Most Ca(OH)2 on the
surface is converted to CaCO3 due to carbonation reaction.
- Generates free strong base catalyst (NaOH) which promotes ASR in concrete results
into cracks formation. Swelling of the gels can cause delamination of the concrete..
- The product just reduces pore size, does not remove surface affinity for water
- Can not be used for stone, bricks, tiles, clay and other substrates.
- pH is over 12 so special precautions must be taken. It is corrosive material.
- Does not last more than few years.
