Carbonated rankinite binder: effect of curing parameters on microstructure, strength development and durability...

Area of Science:

• Materials Science
• Green Chemistry
• Construction Materials

Background:

• Ordinary Portland cement (OPC) has a significant carbon footprint, driving research into sustainable alternatives.
• Rankinite, a hydraulically inactive, low-calcium material, shows promise as an eco-friendly binder.
• The carbonation hardening mechanism of rankinite requires further investigation.

Purpose of the Study:

• To investigate the carbonation hardening of rankinite as an alternative binder to OPC.
• To elucidate the reaction mechanism, limitations, and performance of rankinite.
• To assess the suitability of rankinite for various applications.

Main Methods:

• Rankinite binder preparation and curing at 45°C for 24 hours.
• Spatially resolved microanalysis techniques including Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), Nuclear Magnetic Resonance (NMR), and X-ray Diffraction (XRD).
• Durability testing of the rankinite binder.

Main Results:

• Rankinite achieved a final strength exceeding 100 MPa with only ~50% carbonation.
• The carbonation reaction is diffusion-limited, with dense product layers hindering further carbonation.
• Durability tests confirmed the excellent suitability of rankinite for diverse applications.

Conclusions:

• Rankinite is a viable, environmentally friendly alternative to OPC due to its CO2 absorption and high performance.
• Understanding the diffusion-limited carbonation process is key to optimizing rankinite binder properties.
• Rankinite demonstrates excellent durability, making it attractive for sustainable construction.