New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions


  • M. M. Tashima UNESP – Univ Estadual Paulista
  • L. Soriano Universitat Politècnica de València
  • J. Monzó Universitat Politècnica de València
  • M. V. Borrachero Universitat Politècnica de València
  • J. L. Akasaki UNESP – Univ Estadual Paulista
  • J. Payá Universitat Politècnica de València



Reaction, Characterization, Siliceous pozzolan, Silica fume, Rice husk ash


A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide:pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH)2 in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 °C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels.


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How to Cite

Tashima, M. M., Soriano, L., Monzó, J., Borrachero, M. V., Akasaki, J. L., & Payá, J. (2014). New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions. Materiales De Construcción, 64(316), e032.



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