New Insights into the Sustainability of Ultra High-Performance Concrete (UHPC) and its Eco-Profile Improvement Through the Use of Recycled Aggregates (R-UHPC)
Presented By: Davide di Summa, Politecnico Milano
Nowadays, the use of Ultra High-Performance Concrete (UHPC) is starting to be more and more widespread in the construction market. Nevertheless, due to its initial cost and to the high cement content, usually associated to huge environmental impacts, it is used to be considered as less performing in terms of environmental and economic sustainability in comparison to more traditional solutions such as Ordinary Reinforced Concrete (ORC). In view of this, this paper investigates, through the use of Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) methodologies, the holistic sustainability of UHPC assessing also the potential advantages resulting from the use of recycled aggregates instead of virgin ones. In this regard, the self-healing properties of UHPC containing 0 – 2 mm recycled aggregates (R-UHPC) have been prior investigated by means of capillary water absorption tests and microscopic crack healing at predetermined time points following pre-cracking. Then, after having observed that R-UHPC showed better self-healing capabilities in comparison to UHPC, a large-scale case study has been assessed, namely a water basin structure exposed to extremely aggressive environment (chlorides attack). To better address the potential advantages deriving from the structural performances of UHPC, a Durability Assessed Design (DAD) has been performed. This allowed to design a structure with a wall thickness of 0.40 m as for the reference ORC solution, reduced up to 0.15 m and 0.10 m as or the UHPC one, depending on whether a uniform wall or a slab supported by buttresses has been designed. With regard to the use of recycled aggregates, it has been supposed the replacement of 30% of the aggregates for the reference structure while 100% has been accounted for the UHPC solution. The comparison of UHPC structure to the ORC one already outlined interesting results such as more than 50% of reduction for the Terrestrial Ecotoxicity impact indicator.
