Date recorded: July 13 2017
Duration: 45 minutes 0 seconds
Presented by: Luciano de Andrade Gobbo
Pozzolan are a broad class of siliceous or siliceous and aluminous materials which, in themselves posses little or no cementitious value but which will, in finely divided form and in the presence of water, react chemically with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties. The quantification of the capacity of a pozzolan to react with calcium hydroxide and water is given by measuring its pozzolanic activity. Amorphous (glassy) fractions have an important role in the pozzolanic activity.
The aim of this work is to present results and steps on the analysis of glass content of some pozzolanic materials. Some fly ash and natural pozzolan were used on the quantification perfomed with X-ray diffraction using the external standard method together with the Rietveld method and an external intensity standard is used to put all Rietveld quantities onto an absolute scale. The standard determines the instrument intensity constant, the so called K-factor and can be any 100% crystalline material consisting of one or of several phases. In this study the external standards were Rutile (TiO2), Corundum (Al2O3) and also Zincite (ZnO). The fly ash samples were mainly composed by mullite, quartz, hematite and glass and the natural pozzolan of aluminosilicate glass and also quartz, feldspar and some clay mineral.