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.