Industrial Wastes as Filler in Bituminous Materials for Construction Industry: Toward Circular Economy

A circular economy creates a connection between extraction, manufacturing, and disposal of materials and reduces the pressure on the consumption of natural resources. Thus, there is a need for using materials as long as possible and recycling them back into economy. As an opportunity for circular economy, this study describes the preparation of a new composite material based on waste as an alternative to the bituminous mastic used presently in the construction industry. The new material replaces the commercial filler prepared from nonrenewable resources with a composite based on two industrial wastes (stone dust and waste cooking oil). The simplicity of the preparation method along with environmental and economic advantages encourages in using this modified composite material as an effective replacement in the mastic currently used. Characterization of materials with different contents of the waste composite in terms of their chemical and physical properties and in reaction with bitumen was done by X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX), Fourier-transform infrared (FTIR), porosity, and surface area measurements. It was observed that stone dust has a higher specific heat capacity than the commercial filler, which may cause the final mastic to heat up more slowly after being exposed to sunlight than the mastic currently used. Selected bituminous mastic compositions were tested at laboratory level and compared to the corresponding standard requirements for commercial products by determining the density, softening point, elastic recovery, and cone penetration. In order to study their compression and dynamic shear response, a dynamic mechanical analyzer (DMA) was used. The results showed that substituting the filler with the waste composite, regardless of the ratio, does not significantly affect the properties of the standard bituminous mastic.