Evolution to carbonated compounds of phases developed on ternary systems materials

Abstract

The incorporation of supplementary cementitious materials to the cement industry is an alternative to reduce consume of large amounts of raw materials and gives up a huge spectrum of blended cements that have been noted not only for its properties of reducing energy consumption and CO2 emission but also for its well known durability properties. In this research work we evaluate ternary systems from CAC/FA/C$ mixtures, focusing on their durability. Selected formulations in the ternary system CAC/FA/C$ hydrated and carbonated have been studied at 14 and 90 days of carbonation time. The carbonation process of ettringite phases and calcium aluminate hydrates proceeded from different formulations, i.e. calcium aluminate cement, fly ash predominance, and calcium sulphate is analysed and discussed by means of infrared spectroscopy, x-ray diffraction but also mechanical properties of samples. The analysis of the results have shown that developed hydrated compounds depend on formulation; after carbonation process, the ettringite decomposition can promote metastable calcium carbonate polymorphs (aragonite and vaterite) due to inorganic compounds (aluminium hydroxide, gypsum, etc) presence. Long term carbonation of the blended samples analysis by Raman spectroscopy allows the identification of a new hydrated phase with carbonate, sulphate and calcium ions in its structure.