Evaluation of Mechanical Properties of Artificial Lightweight Aggregate Liapor with Different Diameters and Lightweight Concrete Made of Them

In recent years, the structural concrete have been considered by many because of its advantages as low weight, improved thermal and acoustic insulations and better resistance to frost and fire. At present, Liapor or Expanded shale which produced using expansible shale by the dry process and cooking in a horizontal rotary kilns, are one of the most important artificially lightweight aggregate which have widespread application in the construction of concrete structures.
In this study, order to determine the effect of diameter size on specific weight, water absorption and mechanical properties of Liapor lightweight aggregates, various tests were carried out on the three categories of gradation of Liapor. Also, by combining the lightweight aggregate and cement mortar and making concrete specimens with the 10 to 30 volume percent of lightweight aggregate and determining the uniaxial compressive strength, static and dynamic modulus of elasticity and dynamic poisson's ratio, mechanical properties the composite material made of them was evaluated. The results showed that the diameter of lightweight aggregates has significant effect on the the mechanical properties of the aggregates and concrete made of them. According to the SEM images taken from the area of contact between lightweight aggregate and mortar, it was found that the transition zone is less than 10 micrometers and therefore can not have an influence on the mechanical properties of lightweight aggregates.