Alkali–aggregate reaction

Sodium aluminosilicate

Catalysis

Phase (matter)

Engineering

Cementitious

Metallurgy

Materials science

Mineralogy

Slag (welding)

Biochemistry

Carbonatation

Chemical engineering

Carbonation

Organic chemistry

Ground granulated blast-furnace slag

Cement

Alkali metal

Composite material

Calcium aluminosilicate

Chemistry

Carbon dioxide

Aluminosilicate

Cement and Concrete Research

Carbonation of cementitious materials induced by their interaction with atmospheric CO2 is one of the main degradation mechanisms threatening their durability. In this study, a novel thermodynamic model to predict the phase evolution of alkali-activated slags exposed to an accelerated carbonation environment is presented. This model predicts the phase assemblages of carbonated alkali-activated slag cements, as a function of CO2 uptake under 1 v/v % CO2 conditions, considering the bulk slag chemistry and activators used. The changes taking place during the carbonation process regarding the physicochemical properties of the main binding gel, an alkali calcium aluminosilicate hydrate (C-(N)-A-S-H), the secondary reaction products CaAl and MgAl layered double hydroxides, and amorphous aluminosilicate gels, were simulated and discussed. The predictions of the thermodynamic model are in good agreement with experimental data retrieved from the literature, demonstrating that this is a valuable tool for predicting long-term performance of alkali-activated slag cements.

Thermodynamic modelling of phase evolution in alkali-activated slag cements exposed to carbon dioxide