Bending Improvement of CO₂-Activated Materials through Crosslinking of Oligomers

Calcium carbonate is the main carbonation product of most CO2-activated materials (CAMs); however, its brittle nature usually leads to low bending, which represents the major drawback of CAM in its application as a construction material. Herein, the bending of CAM was greatly improved by the addition of triethylamine (TEA) in the carbonation process. Both the grain size of the carbonation product, i.e., calcite, and the intensity ratio of the crystal planes from (104) to (113) obviously increased with the addition of TEA, as shown by the scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements, suggesting the crosslinking of oligomers. Compared with the CAM without TEA, the flexural strength of CAM was significantly improved under optimized curing conditions, which was attributed to the crosslinking of oligomers formed with TEA addition. The present work may provide a promising strategy for improving the bending of CAM materials.