New Developments in Chemical Admixtures-An ACI 212 Update-Viscosity and Rheology-Modifying Admixtures (Recorded Presentation)

Viscosity and Rheology-Modifying Admixtures (Recorded Presentation)

Video Transcription

Video Summary

The presentation, led by Ketan, focuses on the ACI 212 document's Chapter 11, which covers viscosity-modifying admixtures (VMAs), rheology-modifying admixtures (RMAs), and anti-washout admixtures. VMAs improve concrete cohesion by increasing its plastic viscosity, crucial for maintaining structure in high-slump and self-compacting concretes, preventing bleeding and segregation. They are particularly effective in constructions using less desirable materials like recycled aggregates and manufactured sand, contributing to better pumpability, air void stability, and optimized cementitious content. RMAs, on the other hand, reduce the yield stress, enhancing flow without altering the slump or plastic viscosity, useful in extrusion mixes. Anti-washout admixtures are stronger versions of VMAs, used for concrete placements underwater, minimizing cement washout and allowing self-placement. Part of the quality assurance involves selecting appropriate admixtures, regular moisture corrections, and carefully managing the concrete’s raw materials and mix design.

Keywords

viscosity-modifying admixtures

rheology-modifying admixtures

anti-washout admixtures

self-compacting concrete

recycled aggregates

concrete cohesion