No abstract

Among the techniques used to retrofit existing reinforced concrete structures, methods involving Ultra High Performance Fiber Reinforced Cementitious Composites (UHP-FRCC) are widely regarded. However, current practices make the use of this material for in-situ application expensive and complicated to perform. Accordingly, a new method to strengthen existing concrete beams by applying a precast UHP-FRCC layer on the bottom side are introduced and described herein. Two test campaigns are performed with the aim of defining the best conditions at the interface between the reinforcing layer and the existing beam and to reducing the environmental impact of UHP-FRCC mixtures. As a result, the eco-mechanical analysis reveals that the best performances are attained when the adhesion at interface is enhanced by means of steel nails on the upper surface of the UHP-FRCC layer, in which 20% of the cement is replaced by fly ash.

Evaluating which is the best choice between renovating an existing construction or building a new structure in countries like Italy, where a huge post-war un-listed building heritage does not satisfy the current standards and the economic resources are limited, is not trivial. Several parameters come into play, such as such the extent of the construction work, the environmental cost of disposing old materials, the carbon footprint and volume of new materials. This paper is devoted to the analysis of two projects. The first consists of a renovation of a multi-storey existing school built in 1960s having total area of about 9900 m2. The second is a new construction of a three-story school having a total area of about 14000 m2 and made with timber. The results show that the existing school building, although having a lower embodied carbon related to materials, has a higher overall carbon footprint due to the CO2 emissions related to operational energy.