Autoclaved aerated concrete in reinforced building applications: A systematic review of AAC/RAAC in the last 40+ years

UK industry has recently highlighted concerns relating to the structural safety of Reinforced Autoclaved Aerated Concrete (RAAC) in existing structures, together with a small number of collapses without warning. A broad body of scholarly academic research already exists on AAC in Building Structures, though much less on RAAC. Against the fact that extant research is primarily industry-led, there is a lack of a systematic critical review of the body of academic literature available. To achieve this, the paper systematically reviews 92 academic papers filtered from over 480 published studies on AAC/RAAC, each included after applying an exclusion criterion, from 1980 to 2024. The review identifies four drivers for AAC applications in building structures, namely AAC being: 1) a lightweight material, useful in reducing load transfers, 2) an insulating material, against fire, temperature, and sounds, 3) a sustainable material, of a recyclable nature with relatively low carbon emissions, and 4) an economical material because of its composition and ease of use and application. Moreover, it also identifies the popular areas of AAC application within buildings, the processes involved in its production, the material's behaviour and characteristics, the types of reinforcement, and the modes of AAC failure. Such a review of knowledge from the last 40 years will help scholars identify the understudied research gaps and several untapped research areas that are included in the proposed research agenda.