Concrete Superplasticizers

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Concrete Superplasticizers
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What is a superplasticizer

• Developed in the 1960s
• First used in Japan and Germany
• Introduced in the U.S. in the 1970s
• 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

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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)

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Important factors

• Type of plasticizer
• Dosage
• Time of addition of superplasticizer
• Amount of cement

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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

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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