Fabric-reinforced cementitious matrix (FRCM) composites are promising structural materials representing the extension of textile reinforced concrete (TRC) technology to repairing applications. Recent experiences have proven the ability of FRCMs to increase the mechanical performances of existing elements, ensuring economic and environmental sustainability. Since FRCM composites are generally employed in the form of thin externally bonded layers, one of the main advantages is the ability to improve the overall energy absorption capacity, weakly impacting the structural dead weights and the structural stiffness and, as a direct consequence, the inertial force distributions activated by seismic events. In the framework of new regulatory initiatives, the paper aims at proposing simplified numerical approaches for the structural design of retrofitting interventions on existing reinforced concrete structures. To this purpose, the research is addressed at two main levels: i) the material level is investigated on the uniaxial tensile response of FRCM composites, modeled by means of well-established numerical approaches; and ii) the macro-scale level is evaluated and modeled on a double edge wedge splitting (DEWS) specimen, consisting of an under-reinforced concrete substrate retrofitted with two outer FRCM composites. This novel experimental technique, originally introduced to investigate the fracture behavior of fiber-reinforced concrete, allows transferring substrate tensile stresses to the retrofitting layers by means of the sole chemo-mechanical adhesion, allowing to investigate the FRCM delamination and cracking phenomena occurring in the notched ligament zone. It is believed that the analysis of the experimental results, assisted by simplified and advanced non-linear numerical approaches, may represent an effective starting point for the derivation of robust design-oriented models.

Accelerated bridge construction is becoming a subject of major importance and, combined use of steel fibre reinforced concrete (SFRC) and prestressing, this construction technique offers a unique opportunity to fulfill the demand of more sustainable infrastructure with enhanced durability and life-cycle cost reduction. Research projects carried out at Polytechnique Montreal in the past 20 years have demonstrated that the combined use of prestressing, SFRC, prefabrication and ultra-high performance fibre reinforced concrete (UHPFRC) allows developing more economical and durable bridges. A project on precast Tgirders was initiated with the aim of developing a new set of prestressed girders for new bridges in the 10 to 30 m span range using conventional prestressing and shear reinforcement, reduced top flange transverse reinforcement and field-cast UHPFC longitudinal joints between girders. It is anticipated that bridge built with this concept will only require minimum maintenance over a 75-year service life in harsh environmental conditions.

The design of building structures and infrastructures is mainly based on four concepts: safety, serviceability, durability and sustainability. The latter is becoming increasingly relevant in the field of civil engineering. Reinforced concrete structures are subjected to conditions that produce cracks which, if not repaired, can lead to a rapid deterioration and would result in increasing maintenance costs to guarantee the anticipated level of performance. Therefore, self-healing concrete can be very useful in any type of structure, as it allows to control and repair cracks as soon as they to occur. As a matter of fact, the synergy between fibre-reinforced cementitious composites and selfhealing techniques may result in promising solutions. Fibres improve the self-healing process due to their capacity to restrict crack widths and enable multiple crack formation. In particular, cracks smaller than 30-50 μm are able to heal completely. Moreover, in the case of High Performance Fibre Reinforced Cementitious Composites (HPFRCC), high content of cementitious/pozzolanic materials and low water-binder ratios are likely to make the composites naturally conducive to self-healing. In this framework the main goal of this paper is twofold. On the one hand, a state-of-the-art survey on self-healing of fibre-reinforced cementitious composites will be provided. This will be analysed with the goal of providing a “healable crack opening based” design concept which could pave the way for the incorporation of healing concepts into design approaches for FRC and also conventional R/C structures. On the other hand, the same state-of-the-art will be instrumental in identifying research needs, which still have to be addressed for the proper use of self-healing fibre-reinforced cementitious composites in the construction field.

Supplementary cementitious materials (SCMs) in conjunction with pre-wetted fine lightweight aggregate to provide internal curing are being increasingly used to produce high performance, low-shrinking concrete to mitigate bridge deck cracking, providing more sustainable projects with a longer service life. Additionally, the SCMs aid in concrete sustainability by reducing the amount of cement needed in these projects. This study examines the density of cracks in bridge decks in Indiana and Utah that incorporated internal curing with various combinations of portland cement and SCMs, specifically, slag cement, Class C and Class F fly ash, and silica fume, in concrete mixtures with water-cementitious material ratios ranging from 0.39 to 0.44. When compared with crack densities in low-cracking high-performance concrete (LC-HPC) and control bridge decks in Kansas, concrete mixtures with a paste content higher than 27% exhibited more cracking, regardless of the use of internal curing or SCMs. Bridge decks with paste contents below 26% that incorporate internal curing and SCMs exhibited low cracking at early ages, although additional surveys will be needed before conclusions on long term behavior can be made.

To improve the eco-efficiency and sustainability of concrete, the cement and concrete industry can exploit many byproducts in applications that could, in some cases, outperform conventional materials made with traditional ingredients. This Special Publication of the American Concrete Institute Committee 555 (Concrete with Recycled Materials) is a contribution towards improving the sustainability of concrete via using recycled materials, such as scrap tire rubber and tire steel wire fiber, GFRP waste, fluff, reclaimed asphalt pavements, recycled latex paint, and recycled concrete aggregate. Advancing knowledge in this area should introduce the use of recycled materials in concrete for applications never considered before, while achieving desirable performance criteria economically, without compromising the quality and long-term performance of the concrete civil infrastructure.