Construction of rigid-flexible interpenetrating network in carbonated magnesium slag composites by in-situ polymerization of acrylamide

The in-situ polymerization of acrylamide (AM) was utilized to tailor the mechanical properties and microstructure of carbonated magnesium slag (MS) composites. The results revealed that appropriate AM incorporation substantially enhanced the flexural and compressive strengths. This enhancement was attributed to the flexible polyacrylamide gels in-situ polymerized from AM, which formed interpenetrating networks with the rigid MS carbonation products, thereby increasing compactness and toughness. AM incorporation did not alter the carbonation products but increased calcite formation. The polyacrylamide gels were uniformly dispersed in the carbonated matrix, reducing porosity and improving density. Moreover, AM formed stable chemical bonds with cations released from MS. The temperature rise and CO2 pressure during carbonation served as the dominating factors that initiated the in-situ polymerization of AM. The established rigid-flexible networks synergistically amplified the flexural and fracture toughness. However, excessive AM reduced the strengths due to phase segregation. The above results provide an efficient approach to establishing polymer-inorganic interpenetrating networks in MS carbonation systems, remarkably improving the mechanical performance. •In-situ polymerized AM forms interpenetrating networks with carbonated MS.•PAM remarkably improves flexural and compressive strengths simultaneously.•Carbonation temperature/CO2 pressure triggers acrylamide in-situ polymerization.