Protección superficial del hormigón reciclado mediante la biodeposición de sílice biogénica

Abstract

The environmental problems linked to the production and management of construction and demolition waste (CDW) are experiencing exponential increase at a global scale. For this reason, the reuse of these wastes as recycled aggregates is proposed as a solution for the sustainable management of materials, promoting the circular economy in the construction industry. However, concrete made with this type of aggregates can have inferior mechanical and durability properties compared to conventional concrete. This thesis addresses this challenge by investigating possible surface treatments that improve the properties of recycled concrete. Specifically, the feasibility of using coatings generated by biodeposition of diatom cellular shells through various techniques is studied. This approach involves the accumulation of the cell bodies of these microalgae as the colony grows and adheres to the surface of the treated material, in order to form layers of biological silica, whose covering effect can provide sealing and repairing properties in this type of cement-based materials. For this purpose, the biofilm formed by the microalgae on the surface of hardened concrete has been explored in detail, in order to obtain ideal conditions for the growth of diatoms, which will improve the efficiency of the deposition of biogenic silica for use as a protective biomaterial. After the silica biofilm is generated, its impact on the mechanical and durability properties of the recycled concrete must be assessed by comparing the protective properties provided by the biotreatment with those of untreated samples. This technique has proven to be highly effective in improving the durability and properties of hardened concrete, with the aspiration of reducing the dependence on synthetic surface treatments in repair or maintenance operations on concrete structures. Thus, this thesis presents biogenic silica biodeposition as a sustainable strategy with significant implications in construction, promoting the circular economy and improving the properties of building materials.