Laboratories Predict the Safe End-of-Life for Concrete Building Structures

AUSTIN, Texas - Oct. 2, 2023 - PRLog -- Concrete building materials are in the news spotlight. In this Formaspace report, we take a look at the role material testing labs play in investigating concrete structural failures and what you can do to keep concrete structures safe.

The Growing Crisis Of Reinforced Autoclaved Aerated Concrete (RAAC) Buildings In The UK

UK news in recent weeks has been dominated by the news that over 50 schools won't be able to reopen in the fall term due to safety concerns that flat roofs and other key structures built from reinforced autoclaved aerated concrete (RAAC) decades ago could suddenly collapse.

RAAC, which also goes by the names "aerobar," "aircrete," and "bubbly" concrete, was originally pioneered in Sweden. When it was introduced in the UK in the 1950s, RAAC was considered an innovative, lightweight, and lower-cost alternative to traditional concrete for use in applications such as flat roofs until its use was discontinued in new structures during the mid-1990s.

Why has this become a crisis, critics might ask, given that from the beginning, RAAC was known to have a finite lifespan of circa 30 years?

One possible explanation is there may be confusion between the economic lifespan of a structure and the actual physical lifespan of structurally sound, safe structures.

Many buildings are said to have an economic lifespan of a certain number of years; 40 years is typical, but future retrofits can usually be updated and recertified to provide additional decades of service.

Unfortunately, structures built with RAAC appear to fall outside this common understanding of a building's lifespan.

Material testing laboratories confirm that as the RAAC material reaches the end of its useful life, it can become inherently dangerous and subject to sudden failure, especially if there has been water intrusion or inadequate reinforcement added during construction. The risk of sudden collapse without warning is the justification for closing schools with roof structures built with RAAC.

NIST Investigates The Champlain Towers South Collapse Near Miami Beach

Fortunately, there do not appear to be any structures built with RAAC in the United States. However, material testing labs are called in to evaluate the soundness of existing concrete structures, and, sadly, sometimes, they are first called to the scene only after a fatal collapse occurs.

Tragedy did occur two years ago in Surfside, Florida (located just north of the Miami Beach city line), where the Champlain Towers South condominium tower partially collapsed in a matter of minutes, costing the lives of 98 residents and guests.

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