Formation of organo-mineral phases at early addition of superplasticizers: The role of alkali sulfates and C3A content

A. Habbaba, Z. Dai, J. Plank

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Most superplasticizers (SPs) exhibit significantly higher dispersing performance when added to an already mixed concrete (delayed mode) instead of addition with mixing water (early addition). Here, the specific parameters which determine this effect were investigated. At first, the tendency of four polycarboxylates and a naphthalene-polycondensate to intercalate into C 3A hydrates was correlated with the flow values of pastes prepared from six different commercial cements at early and delayed addition. It was found that the contents of alkalisulfates and C3A present in the cement samples play the key role. For cements exhibiting a low alkalisulfate/C3A molar ratio (0.04-1.29), huge differences in paste flow at early and delayed addition were observed, presumably because of chemisorption (intercalation) of SP into C3A hydrates. While at high alkalisulfate/C3A molar ratios (~ 2), AFt (ettringite) is formed predominantly, and SP intercalation is impossible. Consequently, similar flow values are attained at early and delayed addition.

Original languageEnglish
Pages (from-to)112-117
Number of pages6
JournalCement and Concrete Research
Volume59
DOIs
StatePublished - May 2014

Keywords

  • Dispersion (A)
  • Organo-mineral phase
  • Polymers (D)
  • Portland cement (D)
  • Sulfate (D)

Fingerprint

Dive into the research topics of 'Formation of organo-mineral phases at early addition of superplasticizers: The role of alkali sulfates and C3A content'. Together they form a unique fingerprint.

Cite this