1. Concrete Superplasticizers

2. 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

3. 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)

4. Important factors Type of plasticizer Dosage Time of addition of superplasticizer Amount of cement

5. 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

6. 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