The feasibility of producing “just add water” alkali-activated self-consolidated (AASCC) mixtures using multi-powder activators and various cement-less binder combinations was evaluated in this study. During this study, fresh properties for mortar mixtures were evaluated by conducting the mini-slump flow test. Moreover, the relative performance of activated mortars and potential interactions among materials used in the mixtures was examined using the isothermal calorimeter. The performance of the hardened mortar mixtures was evaluated after 3, 7 and 28 days by conducting compressive strength tests. Results indicated an increase in the mechanical properties was observed while increasing the dry-powder activator ratio and source material nature for ground and non-ground mixtures.

The production of cement by calcination of limestone releases large amounts of carbon dioxide. Development of concrete quality lead to optimize the sustainability and maintenance phases of concrete structures, so, using supplementary cementitious materials (SCM) is one of the methods adapted to reduce the environmental impact of cement production. In addition, self-healing of concrete appears as a process to considerably improve the durability of a damaged structure [1]. As revealed by most analyses, mineral additions can be used to improve the autogenous healing ability of cementitious materials [2].

In this study, the influence of using a combination of SCMs, such as ground granulated blast furnace slag and metakaolin, on the mechanism of autogenous crack healing was assessed in ternary formula. Self-healing evolution was characterised by means of mechanical tests carried out on notched mortar samples with different substitution ratios. The mechanical recovery was investigated after the healing period. Moreover, the micro-chemical structure of the healing products was determined using various techniques (TGA, SEM/EDS and XRD). The primary results showed that using metakaolin and ground granulated blast furnace slag together greatly improve the healing efficiency.

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.

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.

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.