Polymer dispersion admixtures
Polymer dispersion admixtures are aqueous dispersions of synthetic polymers that form a continuous film when sufficient water is lost from the system. Concrete modified with polymer dispersion is known as polymer cement concrete (PCC). Polymer dispersions reduce the permeability of concrete (improving durability), give a more reliable bond to base materials (concrete and steel), increase toughness and resistance to abrasion/dusting and freeze-thaw action.
The reduced permeability of PCC gives improved resistance to many chemicals and to chloride ingress. Thinner sections and reduced reinforcement cover can be used without compromising durability. These properties make it suitable for bridge deck overlays, roads, sea wall defences, concrete repairs, precast products, industrial floors, etc. For economic reasons, applications are usually restricted to thin sections, i.e. concrete up to about 75 mm thick.
Polymer dispersions are also widely used in screeds, mortars, renders, and grouts.
The durability of PCC is significantly higher than that of unmodified concrete, largely because of its lower permeability and higher tensile strength. PCC has been in wide use since the 1960s and the experience gained has established a high level of confidence.