# Evaluation of 3D Concrete Printing Extrusion Efficiency
## 1 Introduction  
In the last decade, significant advancements have been made in 3D concrete printing (3 DCP) technology [1, 2, 3, 4]. This progress has driven the development of specialized construction materials, including shotcrete [5], geopolymer concrete [6], and ultra-high-performance concrete (UHPC) [7]. Foamed concrete, or cellular lightweight concrete (CLC), has also gained attention as a promising material due to its superior thermal insulation, acoustic properties, and fire resistance [8, 9, 10]. The rapid advancement of 3D-printing technologies, combined with the growing diversity of materials, appears to reflect market demands aimed at mitigating excessive waste production and addressing skilled labor shortages [11, 12]. Within the construction industry, 3D printing is increasingly valued for its environmental benefits, which include design flexibility, automation, reduced waste, lower raw material consumption, and decreased labor costs [13]. These advantages also contribute to substantial production cost savings by eliminating the need for formwork, minimizing labor input, and shortening project timelines, thereby enhancing the competitiveness of modern additive manufacturing technologies compared to traditional construction methods [14]. As a result, interest in 3D printing has extended beyond academic research into the industrial sector, where it is perceived as a means to drive innovation and achieve a competitive advantage over conventional solutions [11, 15]. To establish 3D concrete printing (3 DCP) technology as a key method for manufacturing building elements, standardization is essential [16, 17]. Components produced via 3 DCP must exhibit high repeatability and quality, with an absence of defects that couldcompromise structural integrity [18]. Consequently, scientific research often focuses on the design and operation of print heads, with particular emphasis on the construction of printing nozzles [19; 20] and the functional optimization of print heads [21; 22]. The complexity of 3 DCP technology, which integrates principles from both mechanics and materials engineering, necessitates extensive research, often involving numerical simulations to deepen understanding of specific technical challenges [23; 24; 25]. Given the growing diversity of materials employed in 3 DCP, it is crucial to control all factors influencing the printing process to ensure that modifications in materials or design changes in print-head components do not degrade print quality. Particular attention should be directed toward the potential use of waste materials as raw materials for printable substances, as this may be essential for incorporating sustainable development principles into construction [26]. Ensuring process repeatability in such conditions is critical for the safety and durability of structures. If discontinuities or interruptions occur during extrusion, structural defects may arise, reducing structural strength. Such defects, even if imperceptible, can lead to the narrowing of the deposited layer, weakening interlayer bonds and ultimately compromising the stability and durability of the structure as a whole [27]. Considering the above factors, achieving optimal print-head performance and precise parameter configuration is essential for high-quality 3D printing. Key aspects influencing print quality include:  
1. Continuity of the printed path: The print head must ensure consistent material deposition along the designated path, maintaining uniformity and stable flow dynamics, which are crucial for achieving consistent layer formation;
2. Path stability (width and height): The shape of the printed path must remain stable and precise, with controlled width and height throughout the printing process. This stability is critical for maintaining the structural integrity of the printed element;
3. System ergonomics: The system design should promote ease of use, with user-friendly features such as efficient pre-print setup and easy cleaning of components.