Questworks, an engineering design and consultancy firm in building and construction held a technical seminar on post tension buildings at Strathmore Business School. The one day workshop was attended by engineers, architects, contractors, project managers, quantity surveyors, construction industry service providers and developers. The event aimed at enlightening the target audience on the significance use of post tension concrete design in construction.
Post-tensioned concrete is a variant prestressed concrete where the tendons are tensioned after the surrounding concrete structure has been cast.
Making the first presentation was Dr. Raul Figueroa, Executive Director at Questworks. He started off by giving a brief technical update on post-tensioning buildings and its impact. “Post tensioning is a technique for reinforcing concrete. Post-tension tendons, which are prestressing steel cables inside plastic ducts or sleeves, are positioned in the forms before the concrete is placed. Afterwards, once the concrete has gained strength but before the service loads are applied, the cables are pulled tight, or tensioned, and anchored against the outer edges of the concrete.”
“One of the advantages of post-tensioned reinforced concrete over traditional is that Its improved concrete performance can allow longer spans, reduced structural thickness and material saving compared to reinforced concrete,” he added.
The prestressing method can be used in construction of civil structures such as bridges, dams, silos and tanks, hardstands and pavements as well as building structures.
First used in the late-nineteenth century, prestressed concrete has developed to encompass a wide range of technologies. In Kenya, the technology has been used to construct buildings in Strathmore University, Kenyatta University hostels, Tigoni study center, Pacis Insurance among others. Questworks also participates in other activities like building of solar photovoltaic projects in Mwingi, Strathmore law school and Mariru Estate in Nyeri.
The precast concrete technology has taken a slow growth in Kenya even after it was approved by the Ministry of Urban Planning, Lands and Housing in a bid to provide the much-needed housing for low and middle income earners.