Active rheology control of cementitious materials with responsive polymers

In this chapter, the concept of switchable/smart superplasticizers is introduced. Novel concrete smart superplasticizers that could be triggered by the application of external stimuli (e.g. electric and magnetic fields) have been investigated for the first time. In normal conditions, these superplasticizers act as high-range water reducer agents. However, they undergo chemical and/or physical changes in response to external stimuli and change their properties, enabling rheological changes on-demand. This chapter introduces the concept of switchable/smart superplasticizers. Polyaniline is one of the most studied conducting polymers due to its high electronic conductivity, redox and ion-exchange properties, excellent environmental stability and ease of preparation from common chemicals. Magneto-responsive polymers are an interesting research topic due to their applications in different fields such as biomedical, coatings and microelectronics. TEMPO radicals are known to possess high stability and fast electron transfer kinetics, enabling a fast response triggering effect. Thus, novel concrete superplasticizers consisting of the redox-responsive nitroxide radical, TEMPO and methacrylic acid have been prepared using the RAFT polymerization technique. Isothermal calorimetry can be used to study cement hydration kinetics at a constant temperature, whereby the heat flow release can be monitored over time. The concept of ASC was extended by employing magneto-responsive polymer composites that could immediately respond to applied external magnetic fields.