They either block the pores in the concrete to reduce absorption of water and salts or form an impermeable layer which prevents such materials from passing.
[citation needed] Other forms of damage include alkali-silica reaction (ASR), chemical intrusion, and corrosion of steel reinforcements.
In past decades attempts to protect concrete have included sealers ranging from wax to linseed oil.
Topical sealers may alter the coefficient of friction which can make substrates slick when wet – a condition that can be remedied by adding anti-skid materials.
The chemical reaction bonds active ingredients within the substrate blocking surface moisture.