This technology developed in the UK, which has led to several International patents, involves the external lateral pre-tensioning of Reinforced Concrete (RC), leading to a better utilisation of the confining materials and ductile RC elements.
It is known that the strength and ductility of RC can be enhanced by lateral confinement. Traditionally this is achieved by providing suitable steel links at the construction stage. Due to a variety of reasons, the strengthening of RC columns and flexural elements is required. However, conventional techniques, such as jacketing, are very expensive.
Recently, advanced composite materials (also know as FRP – Fibre Reinforced Composites) and high tensile steel are used to strengthen RC. However, in full-scale applications, due to the relatively small confinement provided, these materials are rarely well utilised, and concrete can fracture well before their full mobilisation.
The confining materials can be pre-tensioned (either directly or through expansive agents) so that their full potential is reached prior to the fracture of the concrete. This can lead to guaranteed enhancement in strength and ductility.