Durability of autoclaved aerated concrete based on Polish experience

Abstract

AbstractThe question of durability in the construction industry applies to building materials, components, and structures. In general, building materials, components, and structures are considered durable if their properties remain stable. Durability characteristics depend on a number of complex factors and conditions and may not always be effectively determined using simple standardized methods. Despite ongoing discussions and research, the question of durability and its measuring methods remains elusive. Studies revealed, for example, that shrinkage, phase composition, and durability of autoclaved aerated concrete (AAC) are interrelated. The durability of a building or structure, as discussed in research papers, involves the durability of products and the (designed and anticipated) useful life. Studies on the durability of AAC have been prompted by the increasing production and use of AAC in the construction industry in Poland, specifically in wall constructions. Researches began in early 1960s and focused on AAC materials in industrial production and AAC partitions in experimental conditions and real‐world residential buildings. The studies examined the levels and distribution of moisture in concrete walls; conclusions have been formulated concerning the drying time, the effects of indoor and outdoor conditions, and the partition orientation relative to the points of the compass. Extended research on AAC durability co‐funded by AAC production plants and the Institute of Ceramics and Building Materials (ICiMB, formerly COBRPB CEBET) were resumed in 1999. The studies examined AAC made with fly ash and sand sampled at 5 cm intervals from partitions of 20—35, 40‐year‐old buildings and AAC stored outdoors under extreme conditions for the period of 21 and 40 years (protected with a tarpaper top cover), exposed to snow during winter. The building's technical condition was evaluated when the concrete samples were collected. The following research questions were addressed: operating moisture levels in partitions made of AAC produced using various production technologies (based on fly ash, sand); mineral composition and porosity structure of AAC after a long period of use (as compared to the mineral composition of “fresh” AAC produced using the same technologies); and whether changes in the tested parameters over time may contribute to AAC destruction, resulting in loss or significant reduction of AAC basic qualities, including compressive strength and frost resistance. The results of these studies will be discussed in this article. An analysis of the results of studies confirms the durability profile of AAC, which should be considered in formulating conclusions about the possible uses of AAC. Further research is needed to determine the limit values of AAC properties in the context of real‐world applications.