Unveiling pore formation and its influence on micromechanical property and stress distribution of 3D printed foam concrete modified with hydroxypropyl methylcellulose and silica fume

The pore features are key parameters that influence the mechanical properties, thermal insulation, and durability of concrete. The impact of the printing process and rheological property adjusting materials on the pore features of bulk filament and the interface between two vertically neighboring filaments (intVNF) of 3D printed foam concrete (3DPFC) was comprehensively investigated. The origin of pore features was analyzed. An appropriate dosage of hydroxypropyl methylcellulose (HPMC) reduces the difference in pore orientation and the porosity between the bulk filament and the intVNF. With the increase of silica fume content, the pore sphericity of 3DPFC becomes better. The elastic modulus of the matrix near the intVNF of 3DPFC shows a discrete distribution, which is affected by the uneven distribution of matrix pores. A force model of bubbles in 3DPFC was proposed. The force analysis of 3DPFC was carried out combined with experimental results and finite element simulation by considering various pore parameters.