创新背景

混凝土作为建筑材料不可或缺的成分，应用和需求量十分庞大，但其主要组成成分沙子并非取之不尽用之不竭，建筑工程发展急需寻找能替代沙子得材料。

创新过程

新加坡南洋理工大学的研究团队寻求使用不可回收玻璃，研究利用将其通过3D打印来替代混凝土结构中常用的沙子。因为玻璃是由二氧化硅制成的，而二氧化硅也是沙子的主要成分，二者的组成具有高度相似。相关论文《使用再生玻璃混凝土的 3D 打印混凝土的可挤压区域参数研究》已于2022年1月25日发表于《建筑工程杂志》。

研究人员将玻璃废料粉碎成粗、中、细、超细和“月尘”五种不同尺寸的碎片来代替混凝土常用骨料——沙子和砾石。然后将磨碎的玻璃与混凝土的其他两种成分水泥和水结合起来。随后混合物由现有的4轴龙门式机器人3D打印机的喷嘴被挤出，创造出一个40厘米高的L形混凝土长凳。

研究人员指出，混凝土在固化之前没有变形或塌陷，流动性足以轻松流过打印机喷嘴。因为玻璃吸水程度比沙子低，制造混凝土所需的水就更少。混凝土固化后的强度接近传统的含沙混凝土。

3D混凝土打印因为缺乏模板配置求可打印混凝土具有自支撑特性，需要考虑混凝土的屈服应力和可挤压性。研究员表示，制作中所用的3D打印玻璃废料可用来替代混凝土中高达100%的沙子。璃肥料再生后的可挤压极限表面的混合设计在可挤压区域具有最大的可建造性，最适合 3D 混凝土打印。在未来建筑施工原料需求方面，再生玻璃越来越有发展前景。

创新关键点

采用3D打印混凝土技术将玻璃废料转化为沙子替代品。

3D printing may turn glass waste into sand 

A team of researchers at Nanyang Technological University in Singapore sought to use non-recyclable glass by 3D printing it to replace the sand commonly used in concrete structures. Because glass is made of silica, which is also a major component of sand, the composition of the two is highly similar. A related paper, "Extrudable region parametrical study of 3D printable concrete using recycled glass concrete", was published in the Journal of Architectural Engineering on January 25, 2022.
The researchers shredded the glass waste into five different sized pieces of coarse, medium, fine, ultrafine and "moon dust" to replace the commonly used aggregates in concrete -- sand and gravel. The ground glass is then combined with cement and water, the other two components of concrete. The mixture was then extruded from the nozzle of an existing 4-axis gantry robotic 3D printer, creating a 40cm-tall L-shaped concrete bench.
The researchers noted that the concrete did not deform or collapse before curing and was fluid enough to flow easily through the printer nozzles. Because glass absorbs less water than sand, less water is required to make concrete. The strength of concrete after curing is close to that of conventional sandy concrete.
3D concrete printing requires the self-supporting properties of printable concrete due to the lack of formwork configuration, and the yield stress and compressibility of concrete need to be considered. The researchers say the 3D-printed glass waste used in the production can be used to replace up to 100 percent of the sand in concrete. The hybrid design of the extrudable limit surface after the regeneration of the glass fertilizer has the greatest buildability in the extrudable area and is most suitable for 3D concrete printing. In terms of the demand for raw materials for construction in the future, recycled glass has more and more development prospects.