Developments in the Built Environment (Apr 2024)
Compressive strength development and microstructure evolution of mortars prepared using reactivated cementitious materials under carbonation curing
Abstract
The effect of carbonation curing on depth-wise carbonation gradient and compressive strength development of RCM was evaluated. The RCM mortars were carbonated for seven curing periods, complemented by a thorough investigation of carbonation degree, phase assemblage, and microstructural at varying depths. Results showed a significant increase in compressive strength, from 3.3 MPa on the first day to 51.7 MPa after seven days and 63.5 MPa after 28 days of carbonation curing. A notable gradient in CaCO3 concentration was observed, decreasing from 41.4% at the surface to 16.8% at 25 mm depths. Additionally, the formation of CaCO3 polymorphs and Ca-modified silica gel in the surface layers was found to enhance microstructural density and impede CO2 penetration, while a higher prevalence of micropores was noted in the inner regions. These findings highlight the potential of optimizing the carbonation regime or employing internal carbonation methods to achieve a more homogeneous microstructure.