Stay in Place Formwork, Encased Reinforced Concrete Column: A Review

Formwork systems are required for almost all cast-in-place concrete construction. However, some forms cost too much, often exceeding 30% of the entire cost of the concrete construction. Thus, the stay-in-place (SIP) formwork, a premanufactured permanent constructional member that holds fresh concrete to the intended sizes and stays in the site to afford loads over the construction lifecycle, could be an auspicious alternative to the classic formwork procedure. Several types of stay-in-place (SIP) formworks for columns have been reviewed, like PVC tubes, CFRP, steel tubes, and the composite of two or more types of stay-in-place (SIP) formwork used together. Moreover, some types of concrete and mortar used as stay-in-place (SIP) formwork have been reviewed. The mechanical, restrain, and deformability characteristics of several types of stay-in-place (SIP) formwork system for concrete columns is discussed. Further, the effect of change in the thickness of several kinds of stay-in-place formworks is highlighted. The impact of the change in the strength level of the core of concrete-filled stay-in-place formworks on the confinement efficiency of stay-in-place formwork is also investigated. Finally, the recommendations for futurity researchers in this area are introduced.