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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1. Schneider, M.; Romer, M.; Tschudin, M.; Bolio, H. (2011) Sustainable cement production – present and future. Cem. Concr. Res. 41, 642–650.

2. Altmann, F.; Mechtcherine, V. (2013) Durability design strategies for new cementitious materials. Cem. Concr. Res. 54, 114–125.

3. Shi, C.; Fernández-Jiménez, A.; Palomo, A. (2011) New cements for 21st century: The pursuit of an alternative to Portland cement. Cem. Concr. Res. 41, 750–763.

4. Payá, J. (2012) La "transmutación" sostenible de los residuos para nuevas materias primas en el ámbito del concreto. Dyna 79, 38–47.

5. Donatello, S.; Freeman-Pask, A.; Tyrer, M.; Cheeseman, C.R. (2010) Effect of milling and acid washing on the pozzolanic activity of incinerator sewage sludge ash. Cem. Concr. Compos. 32, 54–61.

6. Soriano, L.; Monzó, J.; Bonilla, M.; Tashima, M.M.; Payá, J.; Borrachero, M.V. (2013) Effect of pozzolans on the hydration process of Portland cement cured at low temperatures. Cem. Concr. Compos. 42, 41–48.

7. Villar-Cociña, E.; Frías, M.; Valencia-Morales, E.; Rojas, M.I.S. (2005) Validation of a kinetic-diffusive model to characterize pozzolanic reaction kinetics in sugar cane straw-clay ash/lime systems. Mater. Construcc. 55 [278], 29–40.

8. Cruz, J.M.; Payá, J.; Lalinde, L.F.; Fita, I.C. (2011) Evaluation of electric properties of cement mortars containing pozzolans. Mater. Construcc. 61 [301], 7–26.

9. Raask, E.; Bhaskar, M.C. (1975) Pozzolanic activity of pulverized fuel ash. Cem. Concr. Res. 5, 363–376.

10. Luxán, M.P.; Madruga, F.; Saavedra, J. (1989) Rapid evaluation of pozzolanic activity of natural products by conductivity measurements. Cem. Concr. Res. 19, 63–68.

11. Payá, J.; Borrachero, M.V.; Monzó, J.; Peris-Mora, E. (2001) Enhanced conductivity measurement techniques for evaluation of fly ash pozzolanic activity. Cem. Concr. Res. 31, 41–49.

12. Villar-Cociña, E.; Valencia-Morales, E.; González-Rodríguez, R.; Hernández-Ruíz, J. (2003) Kinetics of the pozzolanic reaction between lime and sugar cane Straw ash by electrical conductivity measurement: A kinetic – diffusive model. Cem. Concr. Res. 33, 517–524.

13. Frías, M.; Villar-Cociña, E.; Sánchez de Rojas, M.I.; Valencia-Morales, E.(2005) The effect that different pozzolanic activity methods has on the kinetic constants of the pozzolanic reaction in sugar cane straw-clay ash/lime systems: Application of a kinetic-diffusive model. Cem. Concr. Res. 35, 2137–2142.

14. Sinthaworn, S.; Nimityongskul, P. (2009) Quick monitoring of pozzolanic reactivity of waste ashes. Waste Manage. 29, 1526–1531.

15. Payá, J.; Monzó, J.; Borrachero, M.V.; Mellado, A.; Ordoñez, L.M. (2001) Determination of amorphous silica in rice husk ash by a rapid analytical method. Cem. Concr. Res. 31, 227–231.

16. Martínez-Velandia, D.; Payá, J.; Monzó, J.; Borrachero, M.V. (2011) Effect of sonication on the reactivity of silica fume in Portland cement mortars. Adv. Cem. Res. 23, 23–31.

17. Tashima, M.M.; Fioriti, C.F.; Akasaki, J.L.; Payá, J.; Sousa, L.C.; Melges, J.L.P. (2012) Cinza de casca de arroz altamente reativa: método de produção e atividade pozolânica. Ambiente Construído 12, 151–163.

18. Payá, J.; Monzó, J.; Borrachero, M.V.; Peris-Mora, E.; Amahjour, F. (2000) Mechanical treatment of fly ashes Part IV. Strength development of ground fly ash-cement mortars cured at different temperatures. Cem. Concr. Res. 30, 543–551.



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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