An inspection of 40 structures in the UK constructed prior to 1977 and containing exposed structural lightweight concrete has been carried out. Of these, six structures were selected for detailed study, including the extraction of cores and subsequent laboratory analysis. Following a review of both previous research based on UK lightweight aggregates and the performance of overseas lightweight aggregate concrete structures, the paper describes the condition of structures inspected and presents detailed results of the laboratory studies on six selected structures. There is no evidence from the results of this investigation that lightweight aggregate concrete is any less durable than normal-weight concrete, although it might be more sensitive to poor workmanship. The modern practices of using cement contents in excess of 400 kg/m3, natural sand fines, and water-reducing admixtures, are likely to overcome any concerns regarding the rate of carbonation or early age microcracking.
G.C. Mays and R.A. Barnes