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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - EnDurCrete (New Environmental friendly and Durable conCrete, integrating industrial by-products and hybrid systems, for civil, industrial and offshore applications â€“ EnDurCrete)

Teaser

Summary

Concrete based on ordinary Portland cement (OPC) has been until now the principal structural material for durable construction. Although, compared to wood or steel, concrete is a more sustainable construction material, its production consumes significant amounts of limestone, energy and fuel. Replacing part of the Portland clinker by supplementary cementitious materials (SCMs), such as industrial by-products from other industries, is already a well-established strategy. The main driving force for this development is to improve the environmental friendliness of cements. However, current state of the art concretes based on OPC with very high substitution by SCMs tend to fall behind in terms of performance and durability, which is particularly critical when exposed to severe environmental conditions.

In this context, 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.

The primary objective of the EnDurCrete project is to develop optimized low-clinker multi-component CEM II/C and CEM VI cements. This is achieved by the substitution of a significant part of the clinker with mixtures of ground granulated blast furnace slag and fly ash or ground limestone using the separate grinding technology. Moreover, other technologies are developed within the EnDurCrete project such as nano-enabled smart corrosion inhibitors, self-sensing carbon-based microfillers, multifunctional coatings with self-healing and self-cleaning properties and sensorised non-metallic reinforcement systems. Advanced non-destructive continuous monitoring and testing tools and procedures will be developed and used, including technologies tuned for self-sensing concrete systems. These are intended to complement the conventional durability testing procedures.

Multiscale modelling through behaviour simulations of materials, components and structures are also an important objective of EnDurCrete enabling a long-term durability assessment and a better understanding of the factors affecting the evolution of damage.

Durability aspects are inevitable from a life cycle perspective as the overall energy and material consumption. The EnDurCrete project is expected to lead to a positive LCA balance, strengthening competitiveness of the European industry, and its solutions are meant to be at least 30% more durable and at least 30% cheaper for end-user than current production.

The EnDurCrete materials and developed functionalities will be tested in full-scale demonstrators placed in working sites of tunnels, ports, bridges and offshore structures, in order to prove the enhanced durability and improve the long-term cost efficiency of the new concrete structures in such critical applications (Figure 1).

Work performed

During the first 18 months of the project, novel low-clinker cements and associated concrete mix designs were developed. The different additives technologies were first developed individually with the target of achieving the desired functionalities and further successful implementation into concrete. The first set of data on the hardening of the novel cements and on the durability of developed concretes were collected and the results communicated to the partner in charge of the modelling. The achievements from the EnDurCrete consortium in the first 18 months of the project are listed below:

1. Development of novel low-clinker cements. Several cement compositions were tested in the laboratory to identify the best synergies between the different cement constituents. The development was made using separate grinding technology targeting specific fineness for the ground clinker, ground granulated blast furnace slag, fly ash and ground limestone. Additionally, 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 and durability related strength requirements given by the national standards for the four EnDurCrete demonstrator applications (Figure 2). This included the screening and use of compatible admixtures.

3. Development of concrete additives. 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. The quantities and typologies of carbon-based green micro fillers and carbon-based fibers to achieve good mechanical properties and sufficient electrical conductivity have been investigated. The development of novel environmental-friendly multi-functional coating materials with both self-healing properties and resistance to aggressive agents has also been carried out.

4. Development of sensorized textile reinforced concrete. Textile and sensor specifications were defined and a set of lab-size sensorized concrete samples were produced aiming at being tested in the framework of the second periodic report.

5. Lab scale durability testing and development of advanced non-destructive tools (NDT). To ensure sample homogeneity all laboratory scale samples were casted at the laboratory of one project partner and dispatched to partners responsible for laboratory durability testing. These tests aim to confirm the improved durability of the EnDurCrete solutions and to provide data to verify the numerical models. The first steps of the development of non-intrusive in-field inspection tools took place including extraction of crack information and calibration and testing of the functionality of both carbon-based nano-fillers and the textile reinforcements.

All of the above-mentioned technologies are currently being combined into final EnDurCrete concrete solutions towards the roll out for the production of the demonstrators.

Final results

One of the primary targets of EnDurCrete is to significantly improve the service life of concrete structures compared to current solutions and thus to create durable, sustainable and environmentally friendly building materials with high added-value and long-term cost efficiency. The new low-clinker multi-component Portland cements with high performance together with the new smart corrosion inhibitors developed in EnDurCrete are expected to increase the lifetime of concrete when compared to benchmark concretes.

One added value of EnDurCrete should be an improved understanding of the factors that affect concrete durability. Modelling and simulations applied at micro-mesoscale will be carried out for cement paste, mortar, and concrete. Modelling at macroscale will take it a step further and tackle the entire concrete structures. The combined experimental and computational approach will improve the assessment of long-term durability and service life in severe environmental conditions.

It is also expected that EnDurCrete will promote technical guidelines for novel standards in the field of durability monitoring and testing as well as of new sustainable concrete materials and systems. Alignment with other European initiatives will accelerate knowledge transfer and exchange of expertise.