Application of Phytoremediation to Hydraulic Binders Alkaline Inclusion in Forest Roads Pavement Construction

Abstract

The use of hydraulic binder materials for the improvement of pavement subgrade has many implications for the surrounding ecosystem due to the possible leakage of alkaline compounds. The objective of this study is to evaluate the capacity of plants to remedy the subgrade affected by alkaline inclusion. To reduce the impact and return the subgrade to its original state, a phytoremediation process is studied. The impact of two materials commonly used for the subgrade improvement is analysed – fluid ash (slag) and lime+cement mixture. Three different mixes of plants – Mix A, Mix B and the native natural vegetation Mix N – are proposed. Totally 99 samples were collected and 990 specimens were chemically and geotechnically analysed and statistically evaluated. The success of phytoremediation process for both Mix A and Mix B can be observed. It is considerably higher for the undersurface alkaline inclusion than for the surface one. Mix B appears to be the best for fluid ash binder and Mix A for lime+cement mixture binder. It is worth noting that the native natural vegetation in Mix N also contributes to the phytoremediation process and that the appropriate plant selection – e.g. Mix A and Mix B – can accelerate this process.