Desarrollo de materiales cementantes de baja huella de carbono para aplicaciones en la industria de la construcción y adaptación para fabricación aditiva en arquitectura de bajo impacto ambiental

Abstract

The use of low carbon footprint cements as an alternative to traditional Portland cement is a viable solution for the effective reduction of greenhouse gas emissions. These cements, in turn, allow the use of waste as raw material, which implies a better environmental performance, enabling the circular economy in construction. On the other hand, the use of technologies such as additive manufacturing enables a significant improvement in construction processes, allowing a significant reduction in consumption and thus, the environmental improvement of the construction industry. This is why this work addresses, on the one hand, the development of alternative mechanisms to traditional cementitious materials that involve a reduction of the carbon footprint and the study of their production from waste, with a special focus on those suitable for implementation in the construction market. On the other hand, given the role that additive manufacturing can play in the future of construction, the rheological viability of the materials developed and their adaptation for 3D printing are studied. This Doctoral Thesis consists of three main experimental campaigns. On the one hand, the development of four alternative mechanisms to traditional Portland cement has been carried out, discriminating the formulations that did not meet the requirements for immediate large-scale application and selecting those that presented the best characteristics of each of the mechanisms. Next, the greenhouse gas emissions of each formulation developed have been evaluated, quantifying the equivalent carbon dioxide emissions, and finally, each material has been adapted for use in additive manufacturing in construction. The development of the alternative mechanisms to Portland cement was aimed at reducing the clinker content in cements whose compatibility with current regulations and the requirements of the material allowed their application. The four alternative mechanisms with which the cements of this Thesis have been developed are: alkaline activated cements, supersulphated cements, hybrid cements with alkaline activation and calcined clay cements. In the case of alkaline- activated cements, as they are outside the norm, but have very good performance and excellent environmental behaviour, it was decided to carry out a demonstrative experimental campaign, constructing a full-scale prototype of the façade of a building with the material developed. The modelling and simulation of the life cycles was carried out using the LCA calculation tool SimaPro 9.4.0.2 PhD, with the use of the Ecoinvent v.3.8 (2021) database. Stages A1-A3 in the life cycle analysis have been studied using the IPCC 2021 Global Warming Potential 100 calculation method. The adaptation of the materials for 3D printing was carried out by incorporating thixotropy modifying additives. Viscosity modification has been quantified by rheological tests and the content of each additive has been adapted to the requirements of each formula. The formulas have been tested and iterated in a 3D concrete printer until the feasible dosages for additive manufacturing were reached. Demonstration parts have been produced by 3D printing with each of the materials. The technical feasibility, the regulatory fit and the environmental improvement of the alternative formulas to traditional Portland cement developed have been demonstrated, as well as the feasibility for their application in constructions carried out by additive manufacturin