On the use of weathered rocks in road pavements: An experimental study on Tazekka schists

In Morocco, the management of materials in the road sector is framed by a panoply of technical and normative standards including the Moroccan guide of road earthworks dating from 2002. This document was inspired by its French counterpart and dictates the rules for soil reuse in embankments constituting an important part of the pavement structures. In fact, this document made the use of friable rocks (R category) complicated and leaves to the geotechnical engineer the definition of the necessary precautions. This ambiguity often discourages the administrative services from considering these materials as a reusable deposit and consequently they resort to more stable soils or rocks. This work illustrates the results of an experimental campaign carried out at the level of the Taza Province on several schistose massifs. The conclusions indicate the possibility of reusing these materials by adapting them through secondary treatment. In addition, the laboratory tests carried out on 250 samples from 35 different sites indicate the possibility of using these schists as road aggregates for low traffic roads constituting 70% of the provincial network of Taza. In addition, the treatment of this rock via hydraulic binders constitutes a promising and viable solution allowing its reuse in backfill and roadway subgrades. Indeed, the findings have shown that reduced proportions can significantly improve the behavior of schists and reduce their sensitivity to erosive factors.