Potentials for Using Mechanically Activated Concrete Powder in Stabilized Granular Pavement Mixtures

Stabilization of granular materials is a common practice in transport infrastructure structures. It is used mainly for improving the roadbed or for achieving higher performance of base layers. The traditional approach is to use cement, lime hydrated, hydraulic road binder or standard fly-ash in mixing with soil or granular material (gravel) to get a hydraulically bond mixture which then shows improved bearing capacity and better resistance to water immersion or frost impacts. However, most of the binders (especially cement) show higher carbon footprint and represent therefore increased socio-economic cost of the structure. On the other hand, yearly many old structures are demolished and waste is created often containing huge volume of concrete material, which can be crushed and reused as a granular material. At the same time this material can be treated by high-speed milling (disintegration) process and it is possible to achieve a partial reactivation of the cement components in the concrete. This paper presents some of the achievements in soil stabilized materials and cold recycling mixtures where activated micromilled concrete powder/fine ground recycled concrete (FGRC) was used as an active filler or a binder substitute. The effect of the micromilled concrete powder with respect to its content or combination with other binders or additives is described further. Regular tests like Proctor Standard, CBR or compressive strength, indirect tensile strength or stiffness determination are done. The effect to act as an alternative binder is studied not only it terms of used content, but also with respect to its impact during test specimen curing. Finally, some recommendations are given in this paper with respect to the practical application of such material.