Rapid screening
Traditional screening methods to evaluate the quality of natural pumiceous pozzolans for cement production are not entirely compatible with a production process that requires a steady pace in the supply of high-quality raw materials. To help increase the speed of this evaluation, Cementos Progreso developed a rapid screening method using XRD analysis to determine the hydraulic activity index of pumiceous pozzolanic materials. By Luis Velásquez, Roberto Diaz, Carmela Barrientos and Elvis García, Cementos Progreso SA, Guatemala.
Figure 1: pozzolan distribution in Guatemala – light/dark brown: Quaternary volcanic rocks – yellow: pumice deposits of
different Quaternary origin – orange: Tertiary volcanic rocks – pink: intrusive igneous rocks – green: metamorphic rocks
Natural pumiceous pozzolans are largely vitreous pyroclastic materials that are the result of explosive volcanic eruptions. The violent ejection of incandescent magma into the atmosphere is responsible for the quenching and induction of an amorphous state and consequently for pozzolan reactivity.1
