Cement based materials (CBM) for construction are produced by mixing water, cement and other raw materials. During the initial few hours, the material behaves as a solid suspension, but it changes from a quasi fluid state to a solid state at an instance called ‘setting time’ due to a set of exothermic chemical reactions of cement minerals, known as hydration. From then onwards, the hydration reactions continue and a set of targeted properties reach their high state of maturity after a certain period of time, varying from several hours to a few days or weeks depending on the composition of the cement and conditions that aid the hydration, known as curing. This early hydration period and reactions dictate many important properties of CBM, including their rheological, strength and durability characteristics.

Therefore, an adequate understanding of the behaviour of CBM at these early stages is crucial. Furthermore, CBM undergo significant volumetric changes since early ages due to exothermic reactions that cause increase in temperature and moisture movements in the CBM. These volumetric changes frequently cause cracks at early ages, even in cases where the existing EU regulations are strictly followed. These early cracks impair the material durability, resulting in costly repairs to restore their service performance. Even if cracks do not occur at early ages, a state of internal residual stress is induced that usually limits the capacity of CBM to resist tensile stresses, thus increasing the probability of crack occurrence. This in turn may limit the capability of reinforcement to control the width of cracks in structural members, or loss of prestressing force in the long-term, where applicable. These phenomena may critically compromise their performance in service loads and environments.

In view of the complexities and uncertainties regarding the viscoelastic behaviour and shrinkage effects of different CBM, adequate assurance of important service life parameters such as cracking and deflection of structural reinforced CBM (particularly reinforced concrete) remains challenging in many applications, with frequent deviations being observed in regard to design targets. These limitations are clearly linked to insufficient capacity of existing regulations to describe the real behaviour of CBM both at early ages and throughout the entire service life. Any undesirable CBM behaviour can lead to service lives being compromised for both conventional concrete structures, such as simple one-storey family house or car parks, and large infrastructure facilities, such as bridges, tunnels, water/gas reservoirs, and even critical structures such as concrete containments of nuclear power plants and nuclear storage facilities. Furthermore, frequent and regular maintenance and repair of these structures can increase the life cycle cost of the built infrastructure and negatively contribute to their sustainability.

New priorities are also arising for incorporation of by-products and waste materials in CBM to preserve the raw materials in Europe and to decrease the environmental impact of the production of cement. The development and application of new materials also carries further challenges as society demands undisputable proof of the safety and adequate performance of these new materials. Furthermore, the inclusion of new additional materials in CBM frequently induces changes in performance that need to be taken into account by designers.

Recent scientific advances through experimental and numerical research have been addressing many of the issues raised above, with important opportunities being clearly identified towards more adequate integrated approaches to the evaluation and prediction of behaviour of cement-based materials and structures. These efforts were made by a wide range of research specialists worldwide, particularly in Europe. Even though millions of Euros have been spent on research on the subject (both by using national and EU funds), there are five fundamental levels of integration that are currently insufficient or even lacking in terms of Europe-wide research and application, which are thus relevant features of this COST Action: (i) mutual validation efforts between experimental techniques for CBM characterization and parallel development of CBM-related materials; (ii) mutual validation efforts between numerical simulation approaches to predict the service life of CBM materials and structures; (iii) mutual interaction between experimental and numerical research so as to establish integrated approaches that match adequate characterization techniques/strategies with the corresponding simulation/prediction tools; (iv) mutual interaction between developers of new products (either materials, experimental techniques or software) with companies at continental level to promote transition of new knowledge to the market; (v) effective joint efforts of the scientific community to produce guidelines and recommendations that accelerate the creation of new standards for construction. Consequently, the impact of this COST Action is relevant both at the scientific/technological levels through the unprecedented integration of knowledge, but also at the economic/societal level due to product development, drafting of guidelines/recommendations and interaction with standardization organisations, such as CEN. However, to achieve this, efforts need to focus on harnessing the research on CBM, not only at the level of countries involved, but also at the level of the numerous sub-specialties involved. The congregation of a large number of countries that a COST Action allows makes it the most adequate funding tool to promote this proposal’s aims. Fundamental to this proposal is that research activities can solely rely on funds that each partner can deploy, and, hence, the main focus of the proposal is centred on activities that are mainly dependent on networking and joint research, which is precisely the purpose of COST Actions.

Apart from the acceleration of knowledge transfer to societal applications, there is a very strong potential for new innovations based on the exchange and sharing of knowledge that would otherwise be unfeasible. The new ideas and networking confidence provided by this COST Action will nurture the necessary conditions for new funding request applications that can further deepen the impact of the Action and contribute to the perpetuation of its effects. In fact, an interesting analogy can be made between the process of cement hydration and relationship of the researchers involved in this proposal with the COST Action funding. One may consider that each cement particle represents an isolated country with its own research teams, equipment and funds. Conversely, water (and mixing procedure) represents the opportunity in this COST Action. Once water and cement are together, the hydration reaction is spontaneous due to the potential energy within the cement particles themselves. This leads to strong interconnection between particles that end up constituting a macroscopic solid. That is what this COST Action is about. It is therefore important for Europe to grant a wide collaborative network that gathers partners from research, equipment manufacturing, software development and construction industry. This not only brings an integrated outcome to recent developments, but also has the potential to create new innovations.