Calcium oxychloride formation in pastes containing supplementary cementitious materials: Thoughts on the role of cement and supplementary cementitious materials reactivity

  • Prannoy Suraneni Oregon State University http://orcid.org/0000-0002-0899-2601
  • Vahid Jafari Azad Oregon State University
  • Burkan O. Isgor Oregon State University
  • William Jason Weiss Oregon State University
Keywords: deicing salts, calcium oxychloride, differential scanning calorimetry, thermogravimetric analysis, thermodynamic analysis

Abstract

Over the last decade many concrete pavements in North America have begun to show excessive damage at the joints. This damage appears to be due to two primary causes: classic freeze-thaw damage due to local saturation caused by the pooling of water at the joints, and formation of an expansive phase known as calcium oxychloride due to a reaction between chloride-based deicing salts and calcium hydroxide in concrete. This letter explores the formation of calcium oxychloride in cementitious matrices based on constituent materials and mixture compositions. Low temperature differential scanning calorimetry and thermogravimetric analysis were used to quantify the amount of calcium oxychloride and calcium hydroxide, respectively. Thermodynamic modeling was used to predict calcium hydroxide contents from the constituent material compositions. It is shown that calcium oxychloride contents are well correlated with calcium hydroxide contents in cementitious pastes. Supplementary cementitious materials, such as fly ash and slag, can reduce calcium oxychloride formation by reducing the amount of calcium hydroxide. Complexities in the determination of reactivity of supplementary cementitious materials based on their replacement level and different water-to-cement ratios are discussed. Although it is clear that supplementary cementitious materials are beneficial in reducing calcium oxychloride formation, additional analysis tools are needed to more accurately quantify the specific mechanisms (such as dilution, pozzolanic or hydraulic reaction, changes in cement hydration) that result in the beneficial aspects of each supplementary cementitious material.

Author Biographies

Prannoy Suraneni, Oregon State University
Post-doctoral researcher, Civil and Construction Engineering
Vahid Jafari Azad, Oregon State University
Post-doctoral researcher, Civil and Construction Engineering
Burkan O. Isgor, Oregon State University
Professor, Civil and Construction Engineering
William Jason Weiss, Oregon State University
Professor, Civil and Construction Engineering
Published
2016-05-29
How to Cite
Suraneni, P., Azad, V. J., Isgor, B. O. and Weiss, W. J. (2016) “Calcium oxychloride formation in pastes containing supplementary cementitious materials: Thoughts on the role of cement and supplementary cementitious materials reactivity”, RILEM Technical Letters, 10, pp. 24-30. doi: 10.21809/rilemtechlett.2016.7.
Section
Articles