Effect of ultra-sonic activation on early hydration process in 3D concrete printing technology

In this research created binder was adapted for 3D printer and developing process was analysed in detail. According to the research, early setting time and strength is gained due to ettringite crystal growth. Methods for controlling setting time and early hydration process were proposed. Final setting time of developed binders varied from 5 min up to more than 20 min. Density, flexural and compressive strengths were investigated and compared to ordinary Portland cement. Compressive strength of similar to 1 MPa at 20 min and similar to 50 MPa at 28 days can be expected of 3D concrete printed samples. Structure of developed binders was analysed with XRD, SEM and EDX methods, setting time was analysed by semi-adiabatic calorimeter. Phase composition analysis confirmed previous statement (early setting and strength is the result of intensive growth of ettringite crystals). Purposed method allows easier control of printing technology process, thus individual houses and various civil engineer structures can be constructed easier and with less malfunctions. (C) 2018 Elsevier Ltd. All rights reserved.