Effects of the Incorporation of Expanded Clay on the Physical, Mechanical, Thermal and Microstructural Properties of Self-Compacting Lightweight Concrete (SCLC)

Self-compacting lightweight concrete (SCLC) has become one of the most promising materials in civil construction. This work applies expanded clay as a light aggregate in the production of SCLC, seeking to evaluate the influence of the use of this material on the properties in the fresh state, mainly regarding workability, viscosity, passage capacity and resistance to segregation. In addition, density, compressive strength, thermal and microstructural properties were investigated. The results showed that expanded clay improved the workability of concrete when compared to self-compacting concrete (SCC) with conventional aggregates. As for the mechanical characteristics, resulting from the compressive strength, the SCLC, due to its reduced density, presented values lower than those found for the conventional CAA, produced with denser aggregates. It was observed that the use of lightweight aggregates promotes a reduction in thermal conductivity, a performance that guarantees better thermal insulation. As for the microstructural analysis, it was found that, with the use of expanded clay, there was a decrease in pores in the cement paste matrix and in the thickness of the interfacial transition zone (ITZ). It was evident, therefore, that the use of expanded clay maintained the mechanical characteristics and also ensured better thermal insulation than conventional concrete.

Keywords:
self-compacting lightweight concrete; mechanical strength; thermal insulation; microstructure