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CROSS Safety Alert

Concrete system buildings - need for period inspection

Region: CROSS-UK Published: 1 December 2001


Overview

Precast concrete systems were quite widely used in the 1950s to 1970s for the construction of schools, offices and other buildings. Concrete components were mainly reinforced or pretensioned but post-tensioned construction of roof and floor structures was adopted in some systems.

Evidence of corrosion of tendons in post-tensioned components came to light which was associated with exposure of tendons to moisture in voids in ducts and sometimes also the presence of chlorides. The task of determining the soundness of steel tendons is especially difficult for post-tensioned construction since tendon corrosion may not produce any visible signs until sudden structural collapse occurs.

Note: this Safety Alert was published by SCOSS (Standing Committee on Structural Safety). Since March 2021, SCOSS is integrated under the name Collaborative Reporting for Safer Structures (CROSS).

Who should read this?

Those who inspect and maintain older buildings, often in the public sector such as schools, which were system built with pre-stressed concrete components. Owners, surveyors, civil and structural engineers and maintenance staff.

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