Valorization of Mining By-Products for Rammed Earth Construction

Mining and manufacturing produce large amounts of waste. One effective way for the valorization of many inert wastes or by-products from these industries is their use for the development of sustainable construction materials. This work analyzes the ability of different mix proportions of two by-products from mining, a mining clayed sludge, and a spent foundry sand, for the formulation of a by-products based rammed earth construction material. To achieve this objective an experimental laboratory campaign was developed. First, the physic-chemical properties of both by-products were measured, and the geotechnical properties of clayed sludge especially clay content and granulometry were evaluated. Then, these four by-product materials were combined to create three different combinations of soils with continuous granulometric curves, adequate for rammed earth construction, following the available literature. A Standard Proctor test was carried out to determine the optimum dry density and optimal water content of the mixes. Then, the mechanical strength was characterized by Unconfined Compressive Strength (UCS) tests. The proportions of the materials with higher bulk density show a direct relationship with the UCS values obtained. Water immersion was considered for the characterization of the durability of the developed material. During the durability test, the samples lost their integrity. This work shows the ability of these by-product mixes to produce even more sustainable rammed earth constructions with 100% of recycled constituents, achieving the mechanical strength requirement, not durability ones. Further investigations are required to improve this by-product made soil durability performance.