Concrete Superplasticizers

What is a superplasticizer

Developed in the 1960’s First used in Japan and

Germany Introduced in the U.S. in the

1970’s Neutralizes the surface

charges Causes dispersion Releases water in cement

particles Reduces viscosity

Linear polymers containing sulfonic acid groups

Sulfonated melamine-formaldehyde condensates

Sulfonated nephthalene-formaldehyde condensates

Modified lignosulfonates

Polycarboxylate derivatives

Main Purpose Produce flowing

concrete (7”-9” slump increase)

Easy placement (picture: concrete will fill all gaps between rebar)

High-strength (reaches up to 14,000 psi in 7 day break)

Important factors Type of plasticizer

Dosage

Time of addition of superplasticizer

Amount of cement

Benefits Reduce machine wear

(concrete on picture will go from this 1” slump to 9” slump)

Better surface texture Improve strength in

less time Reduce absorption Eliminate fine cracks

Disadvantages

High cost

Brief action (picture: restoration of the Queen Isabella Causeway after collapse in Sep. 15, 2001, time was very important)

Need strong, sealed forms