Concrete properties to a large extent depend on mix design and processing, currently leaving only limited options to actively modify concrete properties during or after casting. This paper gives a (p)review on a more advanced active control of properties of concrete, based on the application of external signals to trigger an intended response in the material, either in fresh or hardened state. Current practices in concrete industry that could be considered as active control are briefly summarized. More advanced active control mechanisms as studied in other fields, e.g. based on hydrogels and other functional polymers, are reviewed and some principles are listed. A specific focus is further given on potential methods for active rheology control. Based on the concepts developed in other fields, substantial progress could be made in order to achieve active control of fresh and hardened concrete properties. However, several challenges remain, like the stability and functioning of the responsive material in a cementitious environment, the applicability of the control signal in a cementitious material, and the economy, logistics and safety of a control system on a construction site or in precast industry. Finding solutions to these challenges will lead to marvelous opportunities in general, and for 3D and even 4D printing more particularly.

中文翻译：

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混凝土性能的主动控制：a (p)review

混凝土性能在很大程度上取决于配合比设计和加工，目前在浇筑过程中或浇筑后积极修改混凝土性能的选择有限。本文基于应用外部信号触发材料（无论是新鲜状态还是硬化状态）的预期响应，对更高级的混凝土性能主动控制进行了 (p) 评论。简要总结了混凝土行业中可被视为主动控制的当前做法。回顾了在其他领域中研究的更先进的主动控制机制，例如基于水凝胶和其他功能性聚合物，并列出了一些原理。进一步特别关注主动流变控制的潜在方法。在其他领域发展的概念的基础上，可以取得实质性进展，以实现对新拌和硬化混凝土性能的主动控制。然而，仍然存在一些挑战，例如响应材料在水泥环境中的稳定性和功能、控制信号在水泥材料中的适用性，以及建筑工地或预制行业控制系统的经济性、物流和安全性. 为这些挑战寻找解决方案将带来绝妙的机会，尤其是 3D 甚至 4D 打印。建筑工地或预制工业中控制系统的物流和安全。为这些挑战寻找解决方案将带来绝妙的机会，尤其是 3D 甚至 4D 打印。建筑工地或预制工业中控制系统的物流和安全。为这些挑战寻找解决方案将带来绝妙的机会，尤其是 3D 甚至 4D 打印。