As 3D printing technology continues to penetrate the construction field, intelligent construction based on concrete 3D printing has become a coveted technological frontier worldwide, crucially reliant on the smooth pumping and extrusion of materials during the 3D printing process to regulate the thixotropic behavior of cement-based composite materials. The Environmental Materials and Ecological Chemistry Research and Development Center at the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, has made new advances in regulating the performance of concrete 3D printing using zeolite inclusions, injecting fresh vitality into the realm of intelligent construction.
Concrete 3D printing technology, with its unique advantages, has demonstrated immense potential in the construction industry. However, achieving the smooth pumping and extrusion of materials during 3D printing remains a pressing challenge. Addressing this challenge, the research team led by Dr. Aiqin Wang at the Lanzhou Institute of Chemical Physics has conducted efficient and non-destructive research on the key common technologies for the disintegration of zeolite crystalline bundles and achieved a series of significant breakthroughs. The relevant research papers have been published in Cement and Concrete Composites and Applied Clay Science.
It is reported that zeolite exhibits excellent thixotropic behavior and compatibility. However, due to strong hydrogen bonds and electrostatic forces, natural zeolite crystals mostly aggregate in nest-like or pile-like structures, lacking the characteristics of nanomaterials. Additionally, the efficient utilization of the unique nanostructure and physicochemical properties of zeolite itself in cement-based composite materials has not been realized.
The team has long been devoted to the efficient and non-destructive disintegration of zeolite crystalline bundles, inventing an integrated process of "roll treatment - pulping purification - high-pressure homogenization - ethanol exchange," achieving the non-destructive disintegration of zeolite crystalline bundles. However, the structural factors such as the disintegration of zeolite crystalline bundles and the aspect ratio of crystals and their correlation with the performance of concrete 3D printing still require further research. Supported by the Key International Cooperation Projects of the International Cooperation Bureau of the Chinese Academy of Sciences, they collaborated with Dr. Ye Qian's research team at the University of Hong Kong to systematically investigate the efficient disintegration of zeolite crystalline bundles of different geological origins, surface charge regulation, and their application in 3D printed concrete.
Through project implementation, an integrated process of "triple-roll treatment - pulping purification - ultrasonic treatment - pressure filtration and dehydration - strong drying" was developed, along with the development of a synchronous surface modification process for the disintegration of zeolite crystalline bundles. This yielded highly dispersed nano-zeolite crystals of different geological origins, elucidating the structure types, crystal lengths, thixotropic properties of zeolite, and the structure-property relationship of their interfacial action and toughening reinforcement performance in 3D printed concrete.
Building upon this foundation, the application of high aspect ratio octahedral zeolite crystals in concrete 3D printing was explored. By regulating the rheological properties of the system, continuous pumping was achieved, significantly enhancing the stacking performance and printable height of 3D printing, thereby realizing the application of nano-zeolite in concrete akin to "rebars." Additionally, introducing nano-zeolite into the system of 3D printed ultra-high-performance high-ductility cement-based composite materials effectively addressed fiber agglomeration issues, enabling continuous pumping and 3D printing, thereby overcoming key bottlenecks in the application of a series of zeolites in concrete 3D printing.
Related Paper Information:
Cement and Concrete Composites
Applied Clay Science
Adding 1% fiber and different mass fractions of nano-attapulgite (a-0%, b-0.25%, c-0.5%) on 3D printing performance. Image provided by Lanzhou Institute of Chemical Physics.
