Obtention of eco-efficient cement-based composites using industrial waste.

Abstract

Portland cement is the main responsible for the low environmental performance of cement-based composites since its production implies the emission of large amounts of carbon dioxide in the atmosphere. Achieving more eco-efficient concrete, therefore, means an effective contribution to mitigating human-made impacts. The search for less aggressive binders and the partial substitution of Portland cement for supplementary materials of low environmental impact are effective mitigation routes that are explored in this thesis. Concomitantly, the consumption of by-products from other productive sectors as inputs in the production of concrete, besides being an effective way of saving natural resources, provides an adequate destination to environmental liabilities. Thus, as part of the work related to this research, a low environmental impact cement produced entirely with industrial and mining wastes was successfully proposed and obtained. This material presented technological characteristics compatible with belitic cements obtained with conventional materials. In addition, supplementary fine materials socalled Engineered Recycled Mineral Admixtures were designed and produced to partially replace Portland cement and increase the packing density of the fine fraction in cementitious matrices. An extensive characterization program of these materials was conducted, as well as performance evaluation in pastes, mortars and concretes, including rheology, hydration kinetics, cementing properties and mechanical performance. Finally, these materials were used in the production of densely packed concretes, where the great potential of the proposed products in the obtention of cementbased composites with high mechanical strength and/or high eco-efficiency was observed.