LAUSR

Abstract The use of lightweight concrete (LWC) in earthquake resistant buildings is beneficial because of the weight and mass reduction of the structures. LWC has been used in the construction industry for many years and while attempts have been made to develop a practical and reliable code for lightweight concrete design worldwide a satisfactory, practical standard for mix design is required. There are a few standards which present methods for designing the mix of LWC such as ACI 211.2. However, in these standards the proposed compressive strength and density determinations cannot be used for all types of lightweight aggregates. The aim of this study is to provide references for three types of lightweight concretes containing clay and natural (mineral) pumice aggregates with the maximum nominal sizes of 12.7 mm (½ in.) and 19.2 mm (¾ in.) respectively. With this intent, hundred specimens of lightweight concrete were made and then tested in the laboratory using these aggregates. After presenting a standard for propositioning and adjusting propositions of the concrete mix three equations were derived using Gene Expression Programing (GEP) to obtain the compressive strength of a specific mixture. Comparison between the actual properties and their predicted counterparts indicated that the proposed derivations are a useful and reliable practical method for use by practicing engineers when designing lightweight concrete mixes.