A kinetic study about the pozzolanic reactivity of loessic soils by conductometric methods: kinetic parameters

Loessic sediments, widely distributed in the Argentine plains, are composed mainly of silt particles, transported and accumulated by wind during Quaternary geological times. At that period an important aeolian process took place together with explosive volcanic activity in the western area of the country. The chemical and mineralogical composition of loess and also their pozzolanic behaviour depend upon the predominance of each geological process. The present paper presents a kinetic study of the pozzolanic activity of loessic soils. The kinetics of reaction in loess/calcium hydroxide solution is investigated by means of electrical conductivity measurements and later the kinetic parameters are quantified by applying a kinetic–diffusive model to the process. The kinetic parameters that characterise the process (in particular the reaction rate constant) were determined in the fitting process of the model. The index of pozzolanic activity evaluated according to the obtained values of the reaction rate constant permits the characterisation of the pozzolanic activity of these materials in a rigorous way. The results show the variability and good pozzolanic properties of the loess analysed.