Enhanced conductivity measurement techniques for evaluation of fly ash pozzolanic activity

Abstract Evaluation of pozzolanic activity of low-lime fly ashes was carried out by means monitoring of conductivity of fly ash suspensions in calcium hydroxide solution. Contribution of soluble salts from fly ashes to conductivity may be taken into account for evaluating pozzolanic properties of fly ashes. The pozzolanic activity was calculated as the percentage of loss in conductivity, %LC, prior the corresponding salinity correction, at several reaction times (100, 1000 and 10 000 s) and at different reaction temperatures (40°C, 60°C and 80°C). Considerations about the influence of hydrated lime/fly ash ratio in conductivity measurements have been described, and 0.04:1 ratio was proposed for yielding best results. Finally, no suitability of the proposed methodology for high-lime fly ashes was demonstrated.

[1]  J. Pera,et al.  Study of the reactivity of clinkers by means of the conductometric test , 1997 .

[2]  M. P. Luxán,et al.  Rapid evaluation of pozzolanic activity of natural products by conductivity measurement , 1989 .

[3]  R. N. Swamy.  International Symposium on the use of PFA in concrete: University of Leeds, Leeds, 14–16 April, 1982 , 1982 .

[4]  B. Marsh,et al.  Pozzolanic and cementitious reactions of fly ash in blended cement pastes , 1988 .

[5]  E. Raask,et al.  Pozzolanic activity of pulverized fuel ash , 1975 .

[6]  R. Sharma,et al.  Semi-theoretical method for the assessment of reactivity of fly ashes , 1993 .

[7]  F. Sybertz.  Comparison of Different Methods for Testing the Pozzolanic Activity of Fly Ashes , 1989, "SP-114: Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete: Proceedings of the Third International Conference".

[8]  Shuichi Sugita,et al.  Evaluation of Pozzolanic Activity of Rice Husk Ash , 1992, "SP-132: Fly Ash, Silica Fume, Slag, and Natural Pozzolans and Natural Pozzolans in Concrete - Proceedings Fourth Interna".

[9]  Caijun Shi,et al.  Acceleration of the reactivity of fly ash by chemical activation , 1995 .

[10]  Jordi Payá,et al.  Mechanical treatment of fly ashes. Part I: Physico-chemical characterization of ground fly ashes , 1995 .

[11]  P. Schubert,et al.  Test methods for determining the properties of fly ash and of fly ash for use in building materials , 1989 .

[12]  F. Lea.  The chemistry of cement and concrete , 1970 .

[13]  K. Ikeda,et al.  Evaluation of pozzolanic activity by the electric resistance measurement method , 1994 .