Experimental procedures for determining the level of segregation of lightweight aggregate concretes

Resumen

In this work, four different segregation indexes were applied to evaluate the segregation phenomenon in lightweight aggregate concretes (LWAC). LWAC permits greater design flexibilities, positively impact the energy consumption of the buildings and may mean a substantial cost saving. However, LWACs are susceptible to present aggregate segregation during mixing, transport, placement and dormant periods, due to density differences between components. Segregation causes a non-uniform distribution of aggregates in the mixture and may strongly affect the strength and durability of the material. These facts justify the use of indexes to properly quantify this phenomenon. Just a few segregation indexes that permit an evaluation of hardened concrete samples were found in the bibliography. The non-destructive ultrasonic pulse velocity method has been widely applied to the investigation of concrete materials and its results can be easily related to the physical properties of the materials, such as the concrete density. In this study, four experimental segregation indexes were tested applying two different types of experimental data: classic methods of density measurement and through ultrasonic velocities. The results prove the effectiveness and precision of the methods proposed and compare their advantages and disadvantages within another method found in the literature