Abstract
This paper provides the formulation and description of the framework and methodology for a Durability Assessment-based Design approach for structures made of the Ultra-High-Durability Concrete materials conceived, produced and investigated in the project ReSHEALience (Rethinking coastal defence and Green-energy Service infrastructures through enHancEd-durAbiLity high-performance cement-based materials) funded by the European Commission within the Horizon 2020 Research and Innovation programme (Call NMBP 2016–2017 topic 06-2017 GA 780624). The project consortium, coordinated by Politecnico di Milano, gathers 13 partners from 7 countries, including 6 academic institutions and 7 industrial partners, covering the whole value chain of the concrete construction industry. The innovative design concept informing the whole approach herein presented has been formulated shifting from a set of prescriptions, mainly referring to material composition and also including, in case, an allowable level of damage defined and quantified in order not to compromise the intended level of “passive” protection of sensitive material and structural parts (deemed-to-satisfy approach; avoidance-of-deterioration approach), to the prediction of the evolution of the serviceability and ultimate limit state performance indicators, as relevant to the application, as a function of scenario-based aging and degradation mechanisms. The new material and design concepts developed in the project are being validated through design, construction and long-term monitoring in six full-scale proofs-of concept, selected as representative of cutting edge economy sectors, such as green energy, Blue Growth and conservation of R/C heritage. As a case study example, in this paper, the approach is applied to a basin for collecting water from a geothermal power plant which has been built using tailored Ultra-High-Durability Concrete (UHDC) mixtures and implementing an innovative precast slab-and-buttress structural concept in order to significantly reduce the thickness of the basin walls. The geothermal water contains a high amount of sulphates and chlorides, hence acting both as static load and chemical aggressive. The main focus of the analysis, and the main novelty of the proposed approach is the prediction of the long-term performance of UHDC structures, combining classical structural design methodologies, including, e.g., cross-section and yield line design approaches, with material degradation laws calibrated through tailored tests. This will allow us to anticipate the evolution of the structural performance, as a function of exposure time to the aggressive environment, which will be validated against continuous monitoring, and pave the way towards a holistic design approach. This moves from the material to the structural durability level, anticipating the evolution of the structural performance and quantifying the remarkable resulting increase in the service life of structures made of UHDC, as compared to companion analogous ones made with ordinary reinforced concrete solutions.
Highlights
The engineering professional and research community along with the society stakeholders has been paying more and more attention to effectively implement the concept of sustainability into the design, construction, management and maintenance of reinforced concrete structures and infrastructures
Ultra-High-Performance (Fiber-Reinforced) Concrete (UHPC/UHPFRC) has been proved a promising category of materials for the aforesaid goal to be pursued, through several applications around the world [1,2,3,4,5,6,7]. This is especially true considering that reinforced concrete (R/C) structures exposed to marine and chemically aggressive environments (XS and XA exposure conditions as per Eurocode 2 [8]) experience several durability time-dependent problems, such as ageing and corrosion of reinforcement, which result in the need of early and often continuous repairs
Since the structure under the study is used to collect geothermal water, which contains a significant amount of chloride and sulphates, the corresponding degradation mechanisms, which are chloride-induced corrosion and concrete leaching, are going to be considered in this study for the formulation of the proposed Durability Assessment Based Design methodology and its validation with reference to the selected pilot case study
Summary
The engineering professional and research community along with the society stakeholders has been paying more and more attention to effectively implement the concept of sustainability into the design, construction, management and maintenance of reinforced concrete structures and infrastructures. Though the verification of some durability-related limit states may include a crack width control, no information is provided on the evolution of such a width along the structure service life, due to interaction with material aging and deterioration phenomena, which can affect (accelerate) the predicted advance of the deterioration mechanism critical front This is due to the fact that most of the currently available design codes have been originally formulated with reference to normal-strength (ordinary Portland cement) concrete and further extended, with some limitations, to the broad category of high-performance concrete. The high level of mechanical and durability performance achieved by UHPC may allow for a profound rethinking of the current structure concepts, in terms of element dimensions, structure shape and material service stress levels
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
