Mae Concrit Awyredig Awtoclafiedig Cyfnerth yn fath o goncrit ysgafn a ddefnyddiwyd wrth adeiladu llawer o adeiladau rhwng y 1950au a'r 1990au. Mae RAAC yn awyredig iawn, ac mae iddo wahanol briodweddau o ran deunydd o'i gymharu â choncrit confensiynol. Mae Llywodraeth Cymru wedi bod yn gweithio gyda Llywodraeth y DU a llywodraethau datganoledig eraill ers 2018 i ystyried y goblygiadau posibl o ran rheoli adeiladau sy'n cynnwys RAAC. Yn haf 2023, dywedodd Adran Addysg y DU fod digwyddiadau wedi dod i'r amlwg dros gyfnod yr haf a arweiniodd at bryder ynghylch risg diogelwch uwch posibl.
RAAC is a form of lightweight concrete used in construction in many buildings between the 1950s and 1990s. RAAC is highly aerated with different material properties to conventional concrete. The Welsh Government has been working with the UK Government and other devolved governments since 2018 to consider the potential management implications for buildings with RAAC. In summer 2023, the UK Department for Education reported incidents had emerged over the summer period which gave rise to concern over a potential higher safety risk.