Active control of properties of concrete: a (p)review

Abstract

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.

Extrusion-based concrete 3D printing from a material perspective: A state-of-the-art review

“…Another approach to tackle the conflicting rheological requirements is by actively controlling the rheological behaviour by external stimuli. By adding a receptive material in the concrete at the mixing stage, activating them using mechanical, electrical, or magnetic signals could allow the active control of the rheological properties [84][85][86]. By activating the receptive material just after the deposition, a sudden increase in yield stress and elastic modulus could be achieved [87].…”

The launch of BMC Materials

“…The proper selection of materials and the way in which they are integrated into products is a key issue that defines our present state-of-the-art, and will determine our future exploitation of materials as an activator and a tool for progress in science and technology. From employing tailored biomaterials for the improvement of cell transplantation and to help tissue regeneration [1], to the development of stimuli responsive materials allowing active control of construction materials [2], materials science research is paramount to progress across all science, technology, engineering and mathematics (STEM) disciplines.…”

An Evaluation of Two Key Extraterritorial Techniques to Bring Human Rights Standards to Bear on Corporate Misconduct<br>Jurisdictional dilemma raised/created by the use of the extraterritorial techniques

“…86 The harshest critics say that this transnational In an article specifically addressing host state sovereignty concerns, Olivier De Schutter notes the traditional understanding that when a state adopts regulations that seek to influence situations extraterritorially, it competes with the sovereignty of the territorially competent state and should only do this in exceptional circumstances. 89 He argues however that theoretically extraterritorial regulation of corporate misconduct facilitates the role of the host state in regulating foreign investors. By ensuring that foreign direct investment contributes to human development and benefits local communities, he continues, extraterritorial regulation enhances rather than restricts the exercise by the host state of its sovereignty.…”