With advancement in building technologies, builders have tried out various systems to address construction challenges and improve efficiency in projects. Over time, some systems have proven to be better suited as regards ease of execution and cost savings on site. One of the systems tried out extensively in building construction is post tension technology.
In post tension technology high tensile steel tendons are placed and stressed to keep the concrete in compression reducing tension stresses under loading. This technology borrowed from the road and bridges industry has been touted as the future of construction as it provides greater flexibility and efficiency in construction of large and complex structures.
Post-tensioning offers direct cost reduction over conventionally reinforced slabs primarily by reducing concrete and rebar material quantities as well as rebar installation labor. Typically, savings of 20% in direct cost are achieved.
Post tensioning design results in reduction of member sizes i.e. thinner slab (1/3 of RC alternative) with less reinforcement. Hence a reduction of material quantities, labor, and material handling costs during construction. Buildings executed with this technology have reduced total building height hence less cladding cost and economical column and footing designs.
Efficiency from use of Post tension technology arises from the faster construction cycles with rapid reuse of formwork. Formwork removal in 4 days after casting compared to 21 days for traditional slabs. Simplified and cheaper formwork as the slabs have flat soffits without down stand beams. This in effect reduces the floor-to-floor height of the buildings by elimination of the down stand beams.