Improving Interlayer Adhesion of Cementitious Materials for 3D Construction Printing

The popularity of additive technologies in construction is increasing every year. At the same time, there are still a significant number of unresolved issues in this area related to the complexity of ensuring uniformity of printing due to technical difficulties with the mortar. One of the main issues is the adhesion of printed layers. This is especially true for continuing the printing process after it has been suspended with the formation of a cold joint. The authors consider the possibility of improving the technological properties of 3D construction printing (3DCP) mortars by introducing redispersible polymer powders (RPPs) and surface-active substances (SASs) into their composition. A comprehensive analysis of the effectiveness of various RPPs and SASs was carried out using standard testing methods to identify the most effective options and combinations of admixtures depending on their structure and mechanism of action. Laboratory tests of the mortar composition for 3DCP using the selected RPPs and SASs were carried out with the imitation of the formation of a cold joint. The most effective combination of RPPs and SASs was used to create the mortar for making the form-forming element using a construction 3D printer. Based on the results of the tests, the patterns of RPPs and SASs influence on the adhesive strength of such mixtures were determined.