Effects of the addition of graphene on the compressive strength of geopolymeric mortar developed from k-feldspar mining waste

Abstract

Contemporary organizations are showing a growing interest in the reuse of solid waste from industrial processes with the intention of reducing environmental impacts and reducing costs. The mining activity is one of the main waste generators in Brazil. In parallel, geopolymeric materials have been gaining prominence in studies that make it a possible substitute for ordinary Portland cement, due to its environmental advantages. Therefore, the present research proposes to study the feasibility of using K-feldspar mining waste as a possible raw material for the manufacture of geopolymer cements. In addition, in line with the latest technological trends, the addition of multi-layered graphene was evaluated as a structural reinforcement for geopolymeric mortar. Graphene was added in three percentages: 0.1 wt.%, 0.3 wt.% and 0.5 wt.%. Specimens were produced in order to evaluate the compressive strength of these materials. As a complementary characterization, the analysis of EDX, laser diffraction particle size and XRD of the waste were performed, as well as SEM and TEM analysis of the graphene used. The results showed that the geopolimerization was effective and that the 0.5% graphene content promoted a significant increase of 65% in the compressive strength. It is concluded, therefore, that with the achieved mechanical strength values, the studied waste can be applied as mortar in auxiliary structures using the geopolymerization technique and that graphene can be used to promote increases in the mechanical strength of the material produced.