A review of the role of lightweight aggregates in the development of mechanical strength of concrete

The application of lightweight aggregates (LWA) in concrete is aimed mainly at the reduction of weight, improvements of durability, or better thermal and acoustic properties. However, some drawbacks associated with the LWA use, such as the reduction of compressive strength, are to be considered as well. In this review, basic characteristics of selected LWA are compiled at first. Then, main factors affecting the mechanical performance of concrete with LWA are analyzed. Finally, based on the literature data a model describing the relationship between the bulk density of LWA, the percentage replacement of natural aggregate, and the resulting mechanical properties of concrete is proposed. This model fits experimental data with the coefficient of determination R2 equal to 92.4, which is better than common porosity-based models. In addition, it can predict the mechanical performance of concrete already in the phase of mix design.