Thermal Properties of Lightweight Concrete with Scrap Tire Rubber-Based Aggregate

Most of waste tires are landfill disposed, which is the most common method. This method will be drastically reduced in the near future due to the recent introduction of European Union directives that include significant restrictions on this practice in favor of alternatives oriented towards material and energy recovery. One of the possible solutions for the use of scrap tire rubber is to incorporate it into concrete, to replace some of the natural aggregate. This paper is aimed at the thermal performance of a lightweight concrete incorporating high volume of crushed waste tires as partial substitution of natural silica aggregate of the same grain size. In order to quantify the effect of waste tires-base aggregate on concrete properties, a reference concrete mix without waste rubber was studied as well. For the applied crushed waste tire rubber, bulk density, matrix density, and particle size distribution were measured. Specific attention was paid to thermal transport and storage properties of waste rubber that were examined in dependence on compaction time. For the developed lightweight concrete, thermal properties were accessed using transient impulse technique, whereas the measurement was done in dependence on moisture content, at the dry state and at the fully water saturated state. Additionally, the investigated thermal properties were plotted as function of porosity and density. Mechanical resistance was also tested. The tested lightweight concrete was found to be an alternative construction material possessing improved thermal insulation function and sufficient mechanical resistance. Furthermore, the environmental advantages caused by reusing used tires and consequently eliminating their disposal should also be taken into consideration.