Printability and efflorescence control of admixtures modified 3D printed white Portland cement-based materials based on the response surface methodology

3D printed white Portland cement-based materials (WPCMs) were supposed to be a promising cementitious material used in the 3D printing of colored and decorated building components due to the excellent whiteness. This paper was concentrated on the rheology, printed structure, and efflorescence control of 3D printed WPCMs modified by the hydroxypropyl methylcellulose (HPMC), calcium formate (CF), and ethylene-vinyl acetate (EVA) powder based on the extrusion-based 3D printing system. The experimental results show that the HPMC and EVA improve the static yield stress of 3D printed WPCMs significantly, however, the reverse phenomenon is true for the CF dosage of 0-1%. When the dosage of CF exceeds 1%, the yield stress increases gradually. Additionally, the printed structure is well built up when the dosages of HPMC is larger than 0.3%. Furthermore, the response surface methodology (RSM) is used to investigate the properties of 3D printed WPCMs with hybrid admixtures due to their different functions. The optimal dosage of hybrid admixtures is determined for realizing controllable rheology and stable printed structure.