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New Environmental friendly and Durable conCrete, integrating industrial by-products and hybrid systems, for civil, industrial and offshore applications – EnDurCrete

Periodic Reporting for period 3 - EnDurCrete (New Environmental friendly and Durable conCrete, integrating industrial by-products and hybrid systems, for civil, industrial and offshore applications – EnDurCrete)

Okres sprawozdawczy: 2020-07-01 do 2021-12-31

Concrete based on ordinary Portland cement (OPC) has been until now the principal structural material for durable construction. However, its production consumes significant amounts of limestone and energy.

One already well-established strategy to remedy the environmental impact of concrete production is to replace the Portland cement clinker by supplementary cementitious materials (SCMs). However, current state of the art concretes with very high contents of SCMs tend to fall behind in terms of performance and durability. For this reason, legislation so far only allows for a clinker replacement either by a restricted number of SCMs or by a maximum proportion of 35 wt% when all SCMs are combined. The first objective of the EnDurCrete project is to develop concretes with optimized low-clinker multi-component CEM II/C and CEM VI cements able to compete with concretes based on current benchmark cements.

A complementary route to improve the overall energy and material consumption of concrete structures is to increase service life, hence decreasing costs of repair or delaying the need for full reconstruction. The second objective of the EnDurCrete project is to develop solutions to further improve concrete durability and early identification of degradation. EnDurCrete partners are working on novel nano- and micro-concrete additive technologies to provide even better material properties, self-sensing and self-healing capacities. Advanced non-destructive continuous monitoring and inspection techniques will complement the conventional durability testing procedures.

Another important aspect of the EnDurCrete project is to develop numerical tools enabling the long-term durability assessment and a better understanding of the factors affecting the evolution of damages. This is done through multiscale modelling of behaviour of materials, components and structures.

The final objective of the project is to test the developed materials and functionalities and to validate numerical models in full-scale demonstrators placed in working sites of tunnels, harbours, bridges and offshore structures. This will prove the enhanced durability and the improved long-term cost efficiency of the new EnDurCrete concretes in such critical applications.
The main achievements of the project are:

1. Development and characterization of novel low-clinker cements. Several cement compositions were tested to identify the best synergies between the different cement constituents. Separate grinding technology was used to target specific fineness for the ground clinker, granulated blast-furnace slag, fly ash and limestone. The production of the best performing CEM II/C and CEM VI cements took place for the first time on an industrial scale.
2. Development of concretes using the novel low-clinker and low-cost cements. Three different concretes were developed based on the workability, strength and durability requirements given by the national standards. This included the screening and use of compatible admixtures. These concretes were then further engineered to accommodate the different additive technologies (see Figure 1).
3. Development of smart corrosion inhibitors. The functionalization of the smart corrosion inhibitors was successfully evaluated in aqueous solution and the production was scaled up reaching the synthesis of nearly 1 kg of product in one batch.
4. Carbon-based additives. The quantities and typologies of carbon-based green additions have been investigated. A mix of fillers and fibres was engineered to reduce electrical impedance (for monitoring purposes) and to enhance compressive and tensile strength of concrete. The related monitoring technology was validated detecting induced degradation and verifying the correlation with the measured electrical impedance.
5. Development of sensorized textile reinforced concrete. Textile and sensor specifications were defined and the best strategy for the damage monitoring procedure established on a set of lab-size sensorized concrete samples, characterized also in terms of mechanical performances up to braking point.
6. Development of other advanced non-destructive tools (NDTs). The development of other non-intrusive in-field inspection tools took place including crack detection and their aperture assessment.
7. Multifunctional protective coatings. Functional agents with self-healing, self-cleaning, anti-moulding and light-reflective properties were developed and successfully integrated in coatings.
8. Lab scale durability testing. Laboratory durability testing was carried out across different laboratories with the aim to confirm the improved durability of the EnDurCrete solutions and to provide data to verify the numerical models. Chloride ingress, carbonation, corrosion resistance and freeze-thaw were tested, showing properties above requirements for the targeted applications.
9. Modelling. Modelling of carbonation and chloride ingress performance of the novel binders has been successfully achieved and compared against results of accelerated durability tests. Increase in service life (between 37% to 97%) of concrete macrostructures were found via computational analyses depending on the application and on the structure studied.
10. Life Cycle Assessment (LCA). Life Cycle Assessment at material level has been performed for the five EnDurCrete innovative sub-products, and at product level for the selected tunnels, harbours, bridges, and offshore structures. The target reduction of Global Warming Potential (-45% GWP) has been reached.

Demonstrator activities. Combining all the technologies developed in EnDurCrete, full scale demonstrator panels and cubes were cast and sent to different demonstrator locations in Europe, in working sites of tunnels and harbours (Spain), bridges (Croatia) and offshore structures (Norway) – see Figure 2-4. Monitoring was carried out continuously, after 6 months and 12 months of exposure and will continue beyond the project end.
The EnDurCrete project aims to develop new cost-effective sustainable concretes for long lasting and added value applications. The concept is based on the integration of novel and optimized low-clinker cement, new nano- and micro- additive technologies and hybrid systems ensuring enhanced durability of concrete structures with self-healing and self-monitoring capacities.

One of the primary targets of EnDurCrete is to significantly improve the service life of concrete structures compared to current solutions. The new low-clinker multi-component Portland cements with high performance together with the new smart fillers and reinforcement developed in EnDurCrete increase the lifetime of concrete. The new EnDurCrete solutions led to a positive LCA balance, strengthening the competitiveness of the European industry. The project achieved a Global Warming Potential (GWP) reduction of more than 45% for concretes that are at least 30% more durable.

One other added value of EnDurCrete is an improved understanding of the factors that affect concrete durability. Modelling and simulations were carried out for cement paste, mortar, and concrete. Modelling at macroscale took the project a step further and tackle the entire concrete structures.

EnDurCrete contributed to technical guidelines for novel standards in the field of durability monitoring and testing. Alignment with other European initiatives will accelerate knowledge transfer and exchange of expertise.
Figure 4: EnDurCrete solutions being tested in demonstrator site of offshore in Norway
Figure 2: Geographical illustration of the sites chosen for the demonstrators
Figure 1: EnDurCrete novel concrete integrating novel additives for improved durability
Figure 3: EnDurCrete solutions being tested in demonstrator site of Krk bridge in Croatia