Regresar

Hydration process of zeolite-rich tuffs and siltstone-blended cement pastes at low W/B ratio, under wet curing condition

Abstract:

An extensive study in blended cement pastes that comprised two different experimental settings was carried out so as to analyse the hydration process and compressive strength evolution up to 91 days. The aim of this study was to understand the hydration process using zeolite-rich tuffs and siltstone as supplementary cementitious materials at low water-to-binder ratio (W/B =.3) under wet curing condition. It was observed that there were two competing reactions, i.e. pozzolanic reaction and carbonation, during the hydration process, thus leading to a decrease in the content of calcium hydroxide (CH); however, carbonation played a more important role than the pozzolanic reaction in consuming it at the given W/B ratio. The total amount of CH consumed by pozzolanic reaction was likely around 8%, while carbonation transformed around 19% of the total amount of CH at 91 days. Although fully hydrated cement paste incorporates.23 g of water per g of cement, only 60% of this value was used at such a W/B ratio. In addition, the amount of normalised water in hydrates increased as the dosage increased by factor of.158% per 1% of dosage. Finally, the optimal dosages at which Zeo1, Zeo2 and Limo showed the highest compressive strength were in the ranges of 12.5-15%, 17.5-20% and 10-12.5%, respectively. © 2014 Taylor & Francis.