Suchergebnisse

Trabajo presentado a la Conference on Durable Concrete for Infrastructure under Severe Conditions, celebrada en Ghent (Belgium) del 10 al 11 de septiembre de 2019. ; The aim of this work is to analyze the enhanced durability performance of an Ultra High Durability Concrete (UHDC) exposed to chemical attack (XA exposure conditions), with reference to an intended application into infrastructures serving geothermal plants. This study is based on a reference Ultra High Performance Concrete (UHPC) with steel fibers and crystalline admixtures (reference mix) and other two mixes that modify in some aspect the reference one: addition of alumina nanofibers (ANF) and addition of cellulose nanocrystals (CNC). Accelerated and short-term tests, complemented with mineralogical and microstructural characterization, have been employed to measure critical durability indicators according to an XA environment. Based on the monitoring and damage evolution of the UHPC under the intended exposure conditions, a criterion for durability performance assessment is being defined in order to understand the differences due to the incorporation of nanoadditions. ; The research activity reported in this paper has been performed in the framework of the ReSHEALience project which has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 760824.

Since concrete is the most widely utilized construction material, several solutions are currently being developed and investigated for enhancing the sustainability of cementitious materials. One of these solutions is based on producing Recycled Concrete Aggregates (RCA) from existing concrete members resulting by either industrial processes or demolitions of existing structures as a whole. Moreover, waste resulting from industrial processes other than the building construction (i.e., tire recycling, production of steel, powders resulting from other depuration processes) are also being considered as possible low-impact constituents for producing structural concrete and Fiber-Reinforced Cementitious Composites (FRCC). Furthermore, the use of natural fibers is another option for producing environmentally-friendly and cost-effective materials, depending on the local availability of raw materials. To promote the use of concretes partially composed of recycled constituents, their influence on the mechanical and durability performance of these concretes have to be deeply investigated and correlated. This was the main goal of the EnCoRe Project (www.encore-fp7.unisa.it), a EU-funded initiative, whose activities and main findings are summarized in this paper. ; The authors wish to acknowledge the support to the networking activities provided by "EnCoRe" project (www.encore-fp7.unisa.it) (FP7-PEOPLE-2011-IRSES, n. 295283) funded by the European Union as part of the 7th Framework Programme for Research and ...

Current solutions for new concrete constructions in Extremely Aggressive Exposures, as recommended and enforced by design codes, are not taking into account new cement-based construction materials, such as Ultra High Performance Fibre Reinforced Concrete, neither new constituents specifically conceived to improve the concrete durability, because of the lack of standards and technical awareness by most designers and contractors. The H2020 ReSHEALience project will upgrade to the concept of Ultra High Durability Concrete (UHDC), combining nano-scale constituents (nano-cellulose, alumina nanofibers) and self-healing promoters (crystalline admixtures). The paper will present the approach pursued in the project together with a synopsis of the results of ongoing research. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 760824. ; peer-reviewed