Structure of Industrial Sacrificial Fragile Cementitious Foams

Sacrificial fragile cementitious foams (SFCFs) act as a core material of the engineered material arresting system (EMAS) installed in airports to enhance the safe take-offs and landings of aircrafts. The foam structures and foaming mechanisms that greatly impact the collapse strength, specific energy, and arresting efficiency of SFCFs, however, have not been fully addressed. Herein, the engineering properties, chemical characteristics, and pore-skeleton structures of three batches of industrial SFCFs were experimentally investigated. Penetration tests showed significant differences in collapse strength and specific energy among the SFCFs with a similar density. Three-dimensional (3D) pore-skeleton structures were resolved by microfocused X-ray computed tomography. The pore-skeleton anisotropy was investigated to uncover the stages of differences in the SFCFs' engineering properties. The results demonstrate that the pore anisotropy rather than the porosity dominates the collapse of cementitious foams. Viscosity-associated nucleation and growth mechanisms were proposed to account for the featured pore-skeleton structures of the SFCFs. The findings would contribute to better pore structure controls of SFCFs toward the improved quality of EMAS.