Objective
To better understand the function, selection and benefits of the broad types of liquid surface treatments for concrete.
Liquid surface treatments for concrete – overview
Liquid treatments come in two broad types:
- Penetrating – densifiers & impregnants
- Film-forming aka Topical – curing compounds, coatings & toppings
Densifiers & Impregnants
Concrete is a porous material. Penetrants (densifiers & impregnants) do their work here.
Coatings & Toppings
Densifiers
- 15% – 20% of the portland cement used in concrete forms into calcium hydroxide as a by-product of the hydration process
- This calcium hydroxide is rather soft and does not contribute to the structural strength of the concrete – it has virtually no value
- Liquid densifiers react with calcium hydroxide and harden, thereby strengthening the concrete surface
Quick summary
The silicate group – Sodium, potassium, magnesium, lithium
Colloidal silica group of products:
Silicate Densifiers
- Chemical hardening & densifying takes place over the course of 1 – 2 weeks, not in hours
- They are not curing compounds
- Should be applied to dry slabs
- Work down to ~ 3 mm max (depends on porosity)
Impregnants
Work by changing the surface chemistry of the top surface of the slab
- Generally, do not change the appearance
- Do not provide any additional abrasion or chemical protection
- Can provide stain protection
- May need to be re-applied from time to time
- EpiMax950
Product Selection Coatings vs Penetrants
Coatings
- mechanical protection
- chemical protection
- eliminate abrasion/dusting
- colour choices
- non-skid
Penetrants
- hardens surface => enable polishing (densifiers)
- stop water entry (impregnants)
Product Selection Coatings vs Densifiers
- Polished concrete surface grind issue
- Coatings: less than 80 -120 metal-bonded
- Densifiers: more than – 120 metal-bonded
Coatings – Selection Clear vs Coloured
Clear
- Economy
- Can add architectural value
Coloured
- Brighten environment
- Gives greater architectural choice
- Delineate safety & hazards
Coatings – Selection Internal vs External
Internal
- Widest choice
- Economy
External
- UV issue
- PU systems
Coatings – Selection Dry vs Wet
Dry
- Widest choice
- Economy
Wet
- Safety
- Anti-slip requirement BCA
Issues to watch out for
- Effect of temperature on work time
- Old slabs & osmosis potential
- Cutting – in with colours
- Joints
