Geological and geotechnical characterization of crushed stone for road construction: case of Boane - Bela vista link road, Mozambique

The management of construction works, taking into account costs, efficiency and safety, is guided by the use of quality materials aimed at safety and long-term durability of the infrastructures. Knowing the properties and characteristics of an aggregate is of great importance to define the most appropriate uses that can be made of it (Hagemann, 2011). Geological Engineering becomes fundamental, giving reinforcement to civil engineering, contributing to the studies of the behavior of geological materials in constructions. The Boane-Bela Vista link road project uses rhyolites for base and sub-base layers and basalts for coating layer. These rocks belong to the Libombos Volcanic Mountains, a very narrow and extensive volcanic chain formed in late Jurassic, during the Gondwana breaking down (GTK, 2016). The present study aims to understand the geological and geotechnical characteristics of the crushed stone used in road construction. To achieve the established aim, this research is based on laboratory analyses of physical, mechanical and petrographic characteristics of the material, in accordance to the South-African Standards (TMH1) and the SATCC Specifications, widely used in SADC region for roads and bridge works. The work is still ongoing, and it is now in the rocks sampling (bulk sampling) stage for laboratory analyses. Some preliminary results obtained through the physical and mechanical characteristics tests performed (ACV, 10% FACT of dry and wet material, Flakiness Index, grading and dust content), fulfill the SATCC specifications. According to these results, it can be concluded that the material used in the project is in suitable and acceptable mechanical conditions, and this can justifies the good quality of the infrastructure and its lifetime.