Influence of sulphate ions on the crystal chemistry of white cement mortars with a high content of marble filler powder

V A Stoyanov,V Petkova,B Kostova

doi:10.1088/1757-899x/951/1/012007

Abstract

Objects of this research are white cement mortars, characterized by both of high content of addition of marble powder and reduced water-cement ratio. The hardened cement mortars, formed after 28-and 120-day curing under standard conditions, are studied. The newly formed phases, containing [SO4]2-, [CO3]2-, [OH]-, etc., are identified using X-ray powder diffraction, infrared spectroscopy and thermal analysis (coupled with analysis of the outgoing gas mixture by mass spectrometry). Based on of the formed calcium silicate hydrates, calcium aluminate hydrates, the influence of sulphate ions is analysed and the mechanism of the thermal decomposition reaction at high temperatures in an oxidizing gas environment is studied. This allows us to establish that the hydration of Portland cement depends on the addition of marble powder (technically calcium carbonate CaCO3), as well as mono- and hemicarboaluminates are formed instead of monosulphoaluminates.

Highlights

Modern building materials have a low footprint on the environment and lower energy costs for their production [1, 2, 3]
Based on of the formed calcium silicate hydrates, calcium aluminate hydrates, the influence of sulphate ions is analysed and the mechanism of the thermal decomposition reaction at high temperatures in an oxidizing gas environment is studied. This allows us to establish that the hydration of Portland cement depends on the addition of marble powder, as well as mono- and hemicarboaluminates are formed instead of monosulphoaluminates
The phase composition was examined by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TG/DTG-DSC)

Summary

Introduction

Modern building materials have a low footprint on the environment and lower energy costs for their production [1, 2, 3]. One of the main directions for their production is the replacement of some of their components with recycled materials, as this effect is most significant for the expensive and polluting production of cement, mortar and concrete [4, 5]. Limestone quarry waste is often used as inert additives and aggregates for the production of cement-based mortars, but this component increases the content of sulphate and carbonate ions in cement mortars. The aim of this work was to study the amounts of new formed solid phases with [SO4]2-, [CO3]2-, [OH]-, formed at different curing times of mortars based on white Portland cement. Mortars with a high content of inert mineral aggregate (marble powder) and a low water-to-cement ratio were studied. The phase composition was examined by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TG/DTG-DSC)

Objectives

Methods

Results