Papers by Keyword: Active Filler

Abstract: Deterioration of asphalt pavements by water immersion and increased moisture content, presents one of the principal issues for pavement technologists. Especially if concentrating on initial phases of the life-cycle of a pavement. Water in the form of rain precipitation and natural air moisture can be harmful to the bonds between bitumen and aggregate particles, which occurs through the medium deteriorated adhesion on the interface of those phases, or the overall deterioration of the adhesion. Even if it might look at the first glance that bituminous binder creates perfectly impermeable layer of particular aggregate particles, in reality the bitumen film makes unstable coating of aggregates in unequal thicknesses and frequencies. Those weakened areas are far more susceptible to water and moisture affects, which enter the asphalt layer on the boundary of aggregates and bituminous binder. To improve the adhesion between bitumen and aggregates and to get in general better functional characteristics of asphalt mixtures large number of available additives exists in civil engineering. First group can be defined as additives which are added directly to the bituminous binder and provides a kind of bitumen modification. Second group includes mineral additives, which may partially or completely replaced fine-grained particles, normally in the form of filler. In this article the objective was set to qualify effect of mechanically activated microfiller originating from limestone by-products or from recycled concrete as a substitute to fine-grained active filler in asphalt mixtures. The research targeted to utilize waste materials and to contribute to the reduction of overall negative impacts to the environment.

Abstract: This study investigated the effects of different active filler types and contents on the mechanical properties of foamed bitumen treated materials under laboratory conditions. Four different active fillers were tested namely Portland cement, hydrated lime, quicklime and fly ash, at varying concentration of 0%, 1%, 3% and 5%. To evaluate the effects of the additional active fillers, samples were prepared under laboratory conditions and tested using indirect tensile strength, indirect tensile resilient modulus and unconfined compressive strength tests. Based upon our findings, all active filler types except fly ash contributed in improving the strength of foamed bitumen mixtures at different levels. Cement, regardless of adding contents, always provided the highest mechanical performance compared with the other two counterparts: hydrated lime and quicklime. Fly ash was deliberated to be precluded because fly ash on its own did not affect any mechanical strength of foamed bitumen mixes instead it acted as a mineral filler to modify aggregate gradation. The addition of active filler content should be limited within 3% in terms of strength gain and potential cracking prevent when mixing with 4% foamed bitumen content and locally sourced raw materials for base course.