Study of the influence of sand on rheological properties, bubble features and buildability of fresh foamed concrete for 3D printing

•The rheological properties of FC depend on the thickness and rheological properties of paste layer.•Replacing binder with fine sand intensifies the pressure field during the mixing process.•The buildability of 3DPFC is linearly correlated with the average bubble diameter of FC.•A formula is proposed to predict the buildability based on the static yield stress and air content.