The impacts of fabrication systems on 3D concrete printing building forms

Recently, 3D concrete printing (3DCP) technology starts entering the market from factories and laboratories, contributing to the creation of new construction methods and architectural forms. However, since the technologies of most 3DCP institutions are independently developed, there is a lack of consensus in terms of construction methods and development approaches in the industry. In this paper, based on 42 3DCP architectural works completed in last five years, a quantitative analysis was made to evaluate the impacts of the fabrication system on 3DCP building forms. The paper introduced three criteria, including Workspace Index, Geometric Complexity Index, and Tectonic Prospect Index, analyzing and answering the discussions about “adopting in-situ printing or prefabrication”, “using gantry printers or robotic arms” from the perspective of architectural form. By analyzing specific construction methods and design strategies in these projects, the research summarized three development trends, “mobile equipment, algorithmic structure, and intelligent construction”, which will affect the future development of 3DCP building forms. Finally, the paper discussed the advantages, limitations, and potential of four different 3DCP fabrication systems, expecting to point out the directions to further optimize each system and realize more diverse 3DCP buildings.     

水泥基材料3D打印技术研究进展

3D打印技术是一种增材制造、快速成型技术,应用于建筑结构具有建造速度快、建造成本低、无模化施工和建筑垃圾少等优势.本文针对建筑结构的3D打印建造,介绍了三种适用的打印工艺,讨论了3D打印水泥基材料工作性能、力学性能与耐久性能的研究现状,对3D打印配筋增强构件的研究进展做了总结分析,对目前3D打印在建筑领域应用面临的问题...     

原位建筑3D打印两层办公室的施工关键技术

总结了两层办公室项目的原位3D打印施工关键技术.设计开发了具有模块化、高精度、多功能等技术特点大型建筑3D打印机;开发了适合现场3D打印施工的专用添加剂,现场搅拌制备出性能优良的、适合现场施工的3D打印混凝土;提出了一种打印建筑竖向钢筋笼放置和连接方法,解决了打印混凝土结构构造柱根部节点与基础连接的施工难题;通过材料技...     

建筑3D打印力学性能研究综述

3D打印试样的力学性能具有各向异性,其抗压强度与抗折强度的测试方法与传统混凝土相似,但需经过加工与切割,这会造成3D打印试件的变化。在3D打印力学性能中,层间强度最差,大多数试验采用与劈裂强度相似的方法进行测量。由于需加入增稠剂等来调节原材料的流动性,这会影响3D打印试样的力学性能。3D打印接触空气的面积较大,容易造成收缩开裂,可通过加入纤维等来减少收缩。在实际工程中,也可以通过预埋支架等来提高3D打印试样的力学性能。     

磷酸盐水泥在3D打印技术中的应用研究

作为一种新兴技术,3D打印技术的出现得到各个行业的关注。近几年,一些学者开始探索3D打印技术在传统建筑行业中的应用。建筑行业一直是高能耗、高排放行业,3D打印技术的推广,必将减少能源资源的消耗和环境负荷。磷酸盐水泥具有快硬、早强、粘结强度高和良好的生物相容性等特点十分切合3D打印技术对于打印基材的需求。基于磷酸盐水泥技术性能研究,分析了磷酸盐水泥在3D打印基材中的应用技术特性,并对其所面临的问题进行了分析。     

硫铝酸盐水泥和膨胀剂对3D打印混凝土性能影响试验研究

3D打印技术在建筑领域的快速应用有赖于与打印机相兼容的高性能水泥基材料的制备。收缩开裂及耐久性是决定3D打印混凝土长期使用寿命的关键影响因素。通过掺入硫铝酸盐水泥、高效膨胀剂制备一种低收缩高耐久性3D打印混凝土,测试评估3D打印材料的可打印性、收缩和耐久性。同时采用SEM对该材料的水化产物和微观结构进行分析。结果表明:硫铝酸盐水泥掺量为15%~20%时,材料具有优异的可打印性能,膨胀剂掺量为3.0%时,120 d试件尺寸变化率为0.0528%,收缩率小,抗裂性能好;水化产物结构致密,耐久性好,抗氯离子达到RCM-V等级,120 d碳化满足T-Ⅳ等级,抗硫酸盐符合KS90要求,抗冻融符合F100冻融循环要求。     

聚羧酸高效减水剂的掺量对3D打印砂浆性能的影响

以聚羧酸减水剂对3D打印砂浆性能的影响为目标,选定和保持流动度基本不变,调整减水剂掺量和用水量,研究减水剂掺量对3D打印砂浆性能的影响。结果表明,随着减水剂掺量的增大,用水量降低,流动度经时损失降低,堆叠性降低,打印性能先变好后变差,强度增加,且性能变化较大或发生转折时的掺量与最大减水率对应的掺量有关。3D打印砂浆的减水剂最佳掺量不同于普通混凝土,综合考虑宜选中低掺量。     

3D打印技术在道路工程的应用综述

3D打印技术是一种以建模软件为基础,通过使用粘合材料来进行三维打印的技术.本文对3D打印技术的分类和应用进行了介绍,总结了3D打印技术在道路工程上的应用现状,包括道路修复、道路材料和道路施工三个方面,并对未来的研究方向进行了展望.     

3D打印水泥基材料层间界面研究综述

3D打印技术在建筑领域的应用得到广泛关注.与传统施工技术相比,3D打印技术具有诸多技术优势,但仍有一些关键技术问题需要克服,其中打印层间弱界面是一个重点.本文针对3D打印水泥基材料层间界面粘结性能的影响因素、测试方法以及性能特征进行综述.     

化学外加剂对3D打印建筑砂浆流变性能的影响

研究了减水剂和缓凝剂在不同剪切速率下对3D打印建筑砂浆表观黏度、触变性及流变性能的影响。结果表明,增加减水剂的掺量,表观黏度几乎不变,触变性先降低后趋于不变,塑性黏度先降低后增加,屈服应力逐渐降低;缓凝剂会增大3D打印建筑砂浆的表观黏度,提高浆体的屈服应力,掺量较高时会增大砂浆的触变性。掺加适量减水剂和缓凝剂可使3D打印砂浆具有较好的流变性能,使之能适应打印的需求。     

表面改性对光固化3D打印Al2O3陶瓷性能的影响

陶瓷粉体表面改性是一种改善陶瓷浆料流变性能的有效方法,已应用于光固化3D打印用Al2O3陶瓷浆料的制备,然而目前鲜有关于表面改性对光固化3D打印Al2O3陶瓷烧结体性能影响的研究报道.本文采用油酸对Al2O3陶瓷粉体进行表面改性处理,利用光固化3D打印技术制备Al2O3陶瓷,研究表面改性对Al2O3陶瓷浆料流变性能、固...     

多壁碳纳米管对3D打印混凝土性能影响试验研究

3D打印混凝土具有快速成型、无需模具、可精细化数字制作等多种优点,越来越多地应用在建筑行业中,但其强度和工作性能一直是推广应用的主要障碍。研究了碳纳米管对3D打印混凝土工作性能和抗压强度的影响。结果表明,碳纳米管的加入对3D打印混凝土的流动性没有明显影响,最大流动降低率为3.7%;适量碳纳米管对3D打印混凝土抗压强度有提高作用,特别是早期强度,对于使用52.5级硫铝酸盐水泥的试验组,3 d抗压强度较未掺碳纳米管的提高幅度最大,为33.6%。     

3D打印石膏试件的尺寸效应研究

尺寸效应是土木工程领域研究的重要课题.随着3D打印技术的广泛应用,了解3D打印试件的尺寸效应十分重要.本文通过五种尺寸的3D打印石膏立方体试件的单轴抗压试验研究3D打印石膏试件的尺寸效应,结果显示,3D打印石膏试件抗压强度随尺寸增大而降低,不同尺寸试件具有相似的破坏模式,但由于粘结点个数和位置具有一定的随机性,导致小尺...     

岩体结构三维构模技术及其可视化系统研制

根据岩体的构造特征 ,将岩体内部划分成两大类四种基本类型的构造单元 ,即连续型非褶皱岩体、断裂型非褶皱岩体、褶皱型岩体、侵入型岩体 ,并建立相应的空间数据模型。利用柱体构模、表面构模、单轮廓断面构模、多轮廓断面构模技术分别进行这四种类型岩体的三维构模。在此基础上 ,开发岩体结构三维可视化构模系统。     

Effect of nozzle temperature on the emission rate of ultrafine particles during 3D printing

Ultrafine particles and other hazardous materials are emitted during 3D printing, but the effect of temperature on such particles has not been studied systematically. The aim of this study was to evaluate the effect of temperature on the emission rate of particulate matter during fused deposition modeling (FDM) three-dimensional (3D) printing using different filament types. The number concentration of particles was measured with direct-reading instruments in an exposure chamber at various temperatures while using four filament materials during 3D printing. The temperature was increased from 185 to 290°C in 15°C increments, while incorporating the manufacturer-recommended operating conditions. The emission rate increased gradually as the temperature increased for all filament types, and temperature was the key factor affecting the emission rate after filament type. For all filaments, at the lowest operating temperature, the emission rate was 10⁷-10⁹ particles/min, whereas the emission rate at the highest temperature was about 10¹¹ particles/min, that is, 100-10 000 times higher than the emission rate at the lowest temperature. To reduce particle emissions from 3D printing, we recommend printing at the lowest temperature possible or using low-emission materials.     

A road map to find in 3D printing a new design plasticity for construction — The state of art

Recent years are showing a rapid adoption of digital manufacturing techniques to the construction industry, with a focus on additive manufacturing. Although 3D printing for construction (3DPC) has notably advanced in recent years, publications on the subject are recent and date a growth in 2019, indicating that it is a promising technology as it enables greater efficiency with fair consumption of material, minimization of waste generation, encouraging the construction industrialization and enhancing and accelerating the constructive process. This new building system not only gives an optimization of the building process but provides a new approach to the building design materiality. The direct connection between design and manufacturing allows the reduction in the number of the various construction phases needed. It is opening a new and wide range of options both formal and chromatic in customization, avoiding complex formworks, reducing costs and manufacturing time. The creative process has a strict and direct link with the constructive process, straightening design with its materiality. Cement-based materials lead the way, but new alternatives are being explored to further reduce its carbon footprint. In order to leverage its sustainability and enhance the system capacity, initiatives are being pursued to allow the reduction of the use of PC. Geopolimers are taking the first steps in 3DPC. Construction and Demolition Waste (CDW) materials are used to substitute natural aggregates. Even soil is being explored has a structural and aesthetic material. These research trends are opening a wider range of possibilities for architecture and design, broadening the spectrum of color, texture, and formal variations. The concern about textures and colours is not yet evident in many the structures already printed, opening the opportunity for future research. More can be done in the mixture and formal design of this building system, “discovering” other raw materials in others waste. This article aims to make a critical review of technologies, materials and methodologies to support the development of new sustainable materials to be used as a plastic element in the printed structure. A roadmap of 3D printing for construction is presented, and an approach on mix design, properties in the fresh and hardened state, highlighting the possibilities for obtaining alternative materials are pointed. With this review possible directions are presented to find solutions to enhance the sustainability of this system discovering “new” materiality for architecture and design.     

基于虚拟现实和3D打印技术的“虚实结合”教学模式在岩土工程课程中的应用探索

岩土工程课程是一门理论与实践紧密结合的课程,教学内容涉及边坡工程、地下工程、工程岩体等复杂“立体式”结构,传统“平面式”教学的效果往往不佳,学生难以具体且形象地掌握边坡或地下等复杂工程的结构特征。针对这一难题,探索结合虚拟场景和3D打印技术的“虚实结合”教学模式和平台建设,并在课程教学中结合岩土工程实例进行实践应用。实践表明:学生在虚拟场景学习岩土工程的复杂结构,有效解决了学生现场考察面临的成本高、周期长、潜在风险高等不利问题,也更能激发学生的学习兴趣。通过3D打印技术,将虚拟场景和数字模型实体化,能培养学生的实际动手能力和创新思维,提高岩土工程类课程的教学质量。在新工科建设要求背景下,也为学生课外创新性试验等活动提供了平台,有利于教研相长和师生的良性互动。     

基于月壤成分和月球环境的3D打印混凝土结构可行性分析

3D打印工艺在高辐射低温失重的月球环境下凸显巨大的技术潜力,针对月球基地结构的建造技术参数,结合月壤成分、材料比例和细度分布开展了3D打印混凝土配合比设计分析,归纳了月球混凝土3D打印结构的材料配合比,力学性能,工作参数和结构型式等相关研究进展,探讨了真空和低温失重环境下月球3D打印混凝土结构的技术可行性和未来发展趋势。     

Experimental investigation on the invert stability of operating railway tunnels with different drainage systems using 3D printing technology

In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in C...     

起始点逐层等角度移动时3D打印混凝土圆管可连续打印高度

为研究 3D 打印混凝土圆管可连续打印高度随打印路径等参数变化的规律,开展了打印条带质量测试研究,确定了合适的混凝土材料配合比及打印速度;通过无侧限单轴抗压试验和直接剪切试验,研究了早龄期 3D 打印混凝土本构模型;设计了起始点沿周向逐层等角度移动时圆管的4种打印方案,完成了圆管连续打印高度的试验研究;采用生死单元法对打印过程中圆管的受力进行了有限元模拟。结果表明：建立的基于摩尔库伦屈服准则的早龄期 3D 打印混凝土本构模型与试验数据吻合较好;采用 120°等角度移动方案的圆管可连续打印层数最多,为 24 层,较起始点不移动的方案提高了50%;提出的考虑每层条带结合处薄弱特性的有限元建模方法较为准确,模拟得到的圆管变形、失效模式等结果与试验结果吻合较好,可连续打印层数的模拟相对误差在10%以内。