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HYDRATION OF PORTLAND CEMENT IN THE PRESENCE OF SOME AIR ENTRAINING AGENTS

The influence of two types of air entraining agents, Darex AEA and Master Builders MBVR, on the hydration of the cement was studied. This included studies of the variation of pH and the Ca ion concentration, the change of percent non-evaporable water as a indication of the degree of hydration, the calorimetric determination of a cement mix, and the compressive strength. The solutions of 0.1% air entraining agent were used in the study. In all the investigations, cement mixes with and without the air entraining agents were used, so that comparisons could be made. The presence of the air entraining agents which contains polar groups, 800 ion or SO3 ion tends to disturb the chemical equilibria by forming a less soluble Ca ion compound or by physically adsorbing onto the cement particles. However, the extent of the fluctuation can not be expressed quantitatively at this time due to the lack of statistical analysis and the complicated nature of the chemical reactions involved. The hydration of cement with air entraining agents present was found to be somewhat delayed at w/c = 0.4. The effect of the admixture on the temperature rise of a cement mixture in an adiabatic system appeared to be insignificant at the initial stage. The changes of compressive strength after 7 days and 28 days in the 0.1% Darex AEA mix was minimal, while the 0.1% MBVR mix showed some reduction in these values. This study demonstrated the complicated nature of chemical reactions and the importance of on-site evaluation of a concrete mix. (FHWA)

Media Info

  • Pagination: 25 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00349486
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/ME/TP-81/07 Final Rpt.
  • Contract Numbers: BP-81(545)
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Jun 30 1982 12:00AM