Microstructural analysis of coating mortar with partial replacement of natural aggregates by sediment from the Amazon River

Abstract Natural aggregates are among the of most intensively extracted natural materials in the world. This high consumption is a great concern in terms of the depletion of the natural resources used in infrastructure works, which has led to an increase in the search for alternative materials such as recycled aggregates and supplementary materials to Portland cement. Hence, the sediments of rivers have become the target of several studies, leading their quality to improve yearly. As a consequence, river sediments are already being used in the production of concrete and mortar, replacing conventional aggregate (river sand). However, their incorporation can alter the physical, mechanical and microstructural properties of the new compounds, causing anomalies that can compromise the buildings. Thus, the goal of this study is to evaluate the properties (plastic and hardened state), performance (adhesion) and perform a microstructural analysis of coating mortar produced with partial replacement of conventional aggregate by sediment from the Amazon river. The results showed that its use increased the tensile strength of the mortar and caused the formation of stable crystalline products, suggesting the coating acquired greater stability, thus making river sediment a promising material to be used as an aggregate in infrastructure works.