Abstract
3D concrete printing has proven to be a highly favorable construction method in terms of time reduction, cost optimization, architectural flexibility, sustainability, energy use, and others. However, the quality of the final product certainly has a priority over all of these attractive features of the technology. Yet research has given little consideration to investigating the structural integrity of 3D printed concrete structures. Research states that printed structures exhibit sufficient strength as compared to traditionally built structures. Nevertheless, the fact that this strength is sensitive to numerous factors including the machine setup, the printing process, existing conditions (e. g. temperature) and others, should be studied. A major determinant of the reliability and quality of printed structures is the adhesion level between subsequent layers. Poorly adhered concrete surfaces result in weak bonds that in turn reduce rupture strength. The time elapsed between printing successive concrete layers should be bounded to ensure that concrete is flowable enough to adhere to previous layers. For a given concrete mixture design, this time is a function of travel distance and speed. Thus, this research aims at finding the optimum printing path that minimizes the formation of weak bonds without compromising buildability for a given structure and a defined speed. The research employs Discrete Event Simulation to model the printing process for numerous possible travel paths and assess their adequacy by comparing travel time to allowable time limits.
Highlights
3D concrete printing is an additive manufacturing technique that allows an automated transformation of 3D design models to actual structures
It enables printing any desired sophisticated structure regardless of its architectural complexity. This is due to the ability of adjusting many parameters such as the printer head speed, nozzle selection, speed of concrete flow and concrete properties (Bos et al, 2016). Despite these and other advantages, one might question the structural integrity of a member that is constructed by depositing thin layers of concrete as compared to structural members that are monolithically cast
It is of no doubt that the formation of poor bonds or cold joints reduces the tensile strength of a structure
Summary
3D concrete printing is an additive manufacturing technique that allows an automated transformation of 3D design models to actual structures This is achieved through the deposition of concrete layer after layer (El Sakka and Hamzeh, 2017; Rouhana et al, 2014). The major contribution of this automated construction technique is that it allows building low-income structures in a timely manner (Feng and Yuhong, 2014) It enables printing any desired sophisticated structure regardless of its architectural complexity. This is due to the ability of adjusting many parameters such as the printer head speed, nozzle selection, speed of concrete flow and concrete properties (Bos et al, 2016). To what extent are poor bonds formed in 3D printed structures?
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