含粗骨料3D打印混凝土可打印、力学、收缩性能与碳排放分析

Printability,Mechanics,Shrinkage and Carbon Emission Analysis of 3D Printed Concrete with Coarse Aggregates

为阐明粗骨料对3D打印混凝土由打印到长期收缩过程的影响,基于水泥浆体与骨料质量比(P/A)与粗骨料连续、间断级配进行了含粗骨料3D打印混凝土配合比设计,测试了其可建造性、基本力学性能与干燥收缩性能。结果表明:P/A值越低,含粗骨料3D打印混凝土最大可建造高度越高,力学与抗干燥收缩性能也可得提升;间断级配时,大粒径粗骨料比例过高将对可建造性与力学性能产生不良影响,而在减少混凝土干燥收缩上具有良好作用。进一步探究了含粗骨料3D打印混凝土在生产制造阶段减少碳排放的效用,并与3D打印砂浆、传统浇筑方法进行了对比。发现在3D打印混凝土技术中采用粗骨料可有效降低混凝土原材料生产阶段的碳排放,但仍需进一步降低水泥材料的使用量;3D打印混凝土技术在减碳方面的优势主要依赖于无模化施工与减少劳动力的特点,在生产阶段相比传统浇筑可减少36.5%的碳排放,否则将产生约2.6%的更多碳排放。

This paper was to clarify the impact of coarse aggregate from printing to aging on 3D printed concrete.The mix design of 3D printed concrete containing coarse aggregate was conducted at a mass ratio of cement paste to aggregate(P/A)based on a continuous and discontinuous grading of coarse aggregate.The buildability,basic mechanical properties,and drying shrinkage properties were tested.The results show that the lower the P/A value is,the higher the maximum buildable height of 3D printed concrete containing coarse aggregate will be,improving the mechanical and drying shrinkage resistance.The excessive proportion of coarse aggregate with large particle sizes affects the constructability and mechanical properties but has a positive effect on reducing the drying shrinkage of concrete when using discontinuous coarse aggregate gradation.Also,the effectiveness of 3D printed concrete containing coarse aggregate in reducing carbon emissions during the production and manufacturing phase was investigated and compared with that of 3D printed mortar and conventional cast methods.Using coarse aggregate in 3D printing concrete technology can effectively reduce carbon emissions during the production stage of concrete raw materials,and it is still necessary to further reduce the use of cement materials.The advantages of 3D printing concrete technology in carbon reduction mainly depend on modeless construction and labor reduction characteristics.Compared to the conventional cast method,3D printing concrete technology can reduce carbon emissions by 36.5%during production.