Innovative Design Concept of Cooling Water Tanks/Basins in Geothermal Power Plants Using Ultra-High-Performance Fiber-Reinforced Concrete with Enhanced Durability

Abstract

The structure presented in this paper is intended to be used as a prototype reservoir for collecting water coming from the cooling tower of a geothermal plant, and is primarily designed to compare the performance of different materials (traditional reinforced concrete and Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC)) as well to assess the performance of different structural solutions (wall with constant thickness versus wall provided with stiffening buttresses). In the absence of specific code provisions, given the novelty of the UHPFRC used, the main properties used for the design were determined through a dedicated experimental campaign (tensile/flexural properties and shrinkage). The main focus of the design was on the Serviceability Limit States, more specifically the requirements regarding water tightness. Given the rather simple structural layout, especially in the compartments where no stiffening buttresses are present, linear elastic analysis was used to determine the internal actions. The nonlinear behavior ensuing from the peculiar tensile constitutive response of the material was taken into account locally, in order to determine the stress level, the depth of the compression zone and the crack width. The performance was finally compared with the reference compartment (made with ordinary reinforced concrete), through on-site observations and measurements.

Structural validation of geothermal water basins constructed with durability enhanced ultra high performance fiber reinforced concrete (Ultra High Durability Concrete)

“…Summarizing the results and illustration of the different displacement measurements, Fig. 11 is schematically showing the position and the deformed shaped of each wall, together with the results of a yield line analysis, reported in detail in [34] for the comparison purposes. The UHDC columns successfully stiffened the walls of the third basin, shifting the global response mechanism towards a local one, which in turns brings more redundancy to the system.…”

A holistic life cycle design approach to enhance the sustainability of concrete structures

“…To address the aforesaid problem, innovative cement based materials have been developed which, ensuring the self-repair of the cracks upon occurrence or being extremely impervious to the penetration of harmful substances in aggressive environments, improve the durability of the structure they are built of or retrofitted with. [12][13][14][15] It must be highlighted that the durability represents a design target requisite which in current design codes, 16 is achieved through "deemed to satisfy" prescriptions, including minimum water to cement ratio, minimum cement content and minimum concrete cover to guarantee the target service life. Nonetheless, because of the random and sometimes one-of-a-kind characteristics of structural service scenarios, this approach has resulted so far into a continuous need of repairing activities which for ORC structures might represent around 35% of the overall expenses throughout their SL, as already outlined in a previous work for structures exposed to an aggressive chloride environment.…”

Effects of Autogenous and Stimulated Self-Healing on Durability and Mechanical Performance of UHPFRC: Validation of Tailored Test Method through Multi-Performance Healing-Induced Recovery Indices

“…In this respect, the assessment of the healing-induced recovery of the material has to encompass both the durability/transport properties and the mechanical ones, the healingrelated recovery of the latter being likewise responsible, together with the former one, of the stability over time of the structural performance in the intended scenario, with is the truest and broadest meaning of structural durability. This also brings the breakthrough concept of transforming the material from a passive provider of protection into an active player, able to respond to degradation processes as a function of the durability requirements of the engineering application [32]. In this framework, it is evident that the experimental methodology conceived to assess the self-healing capacity of this category of materials has to be soundly based on a multiplicity of tests [33], enabling the quantification of the closure of the cracks as well as the recovery of the durability properties, which surely relies on the former, and of their mechanical tensile properties, which benefit not only from the reconstruction of the through-crack material continuity but also from a healing-induced enhancement of the fiber-matrix bond.…”

“…The material employed has been designed and tested, with reference to its mechanical and durability performance [27,[31][32][33], to be employed for the construction of a tank containing geothermal water and serving cooling towers in a geothermal power plant, as a pilot demonstrator of the Horizon 2020 ReSHEALience project (rethinking coastal defense and green-energy service infrastructures through enHancEd-durAbiLity high-performance cement-based materials-GA 780624-www.uhdc.eu, accessed on 6 October 2021) [5,32].…”