n型筋布置方式对3D打印混凝土抗弯性能的影响  

Effect of Layout of n-Shaped Bar on Flexural Properties of 3D Printed Concrete

作　　者：王振地 李昕泽 王玲 WANG Zhendi;LI Xinze;WANG Ling(China Building Materials Academy,State Key Laboratory of Green Building Materials,Beijing 100024)

机构地区：[1]中国建筑材料科学研究总院有限公司,绿色建筑材料国家重点实验室,北京100024

出　　处：《硅酸盐学报》2025年第1期27-36,共10页Journal of The Chinese Ceramic Society

基　　金：吴中伟青年科技奖项目(ZA-100);中国建材集团原创技术策源地项目(2021YCJS01-2-1)。

摘　　要：挤出式混凝土3D打印技术被认为是最可能实现大型建筑建造的主流工艺,缺少有效的配筋方法是该技术实用化的主要障碍之一。n型筋垂直贯入3D打印混凝土(3DPC)已被证明是行之有效的纵向配筋方法。为评价n型光圆钢筋布局方式对3DPC抗弯性能的影响,定义了钢筋不搭接贯穿度P_(non)和搭接贯穿度P_(ovr),制备了P_(non)和P_(ovr)不同的8种试件,通过三点弯曲加载试验研究了贯穿度对配筋3DPC抗弯强度、荷载位移曲线以及断面形貌的影响。结果表明:不搭接的配筋方式对抗弯强度没有增强效果且破坏模式均为脆性破坏;当n型筋搭接布置时,3DPC的抗弯强度随贯穿度增加而增大,但钢筋的贯穿度对抗弯强度的提升存在一个饱和值。搭接n型筋增强3DPC的破坏模式为韧性破坏,并出现了明显的应变硬化特性。通过讨论得到了配筋率、钢筋贯穿度、3DPC基体抗弯强度对配筋3DPC抗弯强度的影响权重,还对比分析了n型筋(不搭接和搭接)、铆钉与短切直筋等4种纵向配筋方法对3DPC抗弯强度的提升效果,相关结果对配筋参数和方法的选择具有重要的参考价值和指导意义。Introduction Compared with the conventional moulded concrete process,the layer-by-layer stacking process produces a large number of interlayer interfaces in 3D printed concrete(i.e.,3DPC),leading to a low flexural and tensile strength of 3DPC and a poor structural integrity of 3D printed concrete structure,which restricts the development and large-scale application of concrete 3D printing technology.Reinforcement is considered as one of the most effective measures to improve the flexural and tensile properties of 3D printed structures and enhance the structural integrity.Various reinforcement techniques for 3DPC,such as fiber reinforcement and transverse reinforcement,are developed,but all of them fail to effectively reinforce the interlayers.A longitudinal reinforcing approach involving short-cut straight and n-shaped bars was firstly proposed in 2018,and some work showed that longitudinal reinforcing method of n-shaped bar could enhance the mechanical properties of 3DPC.In this paper,the influences of the penetration degree of the n-shaped bars and the overlapping conditions on the flexural properties of 3DPC were investigated,and the damage process of 3DPC was analyzed via crack displacement and section morphology.The different reinforcing methods were compared.Methods Portland cement P·I 42.5 according to Chinese standard and natural river sand with a fineness modulus of 3.4 as a fine aggregate were used.Hydroxypropyl methylcellulose(HPMC)with an apparent viscosity of 198 Pa·s was selected as a viscosity enhancing agent and a bauxite-based powdered accelerator with a fineness(80μm square-hole sieve residue)of 9%was used to adjust the thixotropy and buildability of 3DPC.A polycarboxylic acid-based high-performance superplasticizer with a solid content of 39%was used to adjust the flowability of the printed materials.In this work,a ratio of the layer number penetrated by n-shaped bar(L_P)to the total layer number(L_P)was defined as a penetration degree(P)including overlapped penetration degree P_(ovr)and non

关 键 词：n型筋 3D打印混凝土 贯穿度 抗弯性能 

分 类 号：TU528[建筑科学—建筑技术科学]