Self-healing cementitious composites are a broad category of smart construction materials to which strong and highly qualified research efforts are currently being devoted worldwide, with the aim of providing a sound scientific background to their consistent, and – design-wise – “consciously safe”, use in the engineering practice. Tailored additions can be employed to enhance the self-healing capacity, among which the so-called crystalline admixtures, play a prominent role. Crystalline admixtures consist of proprietary active chemicals, which, because of their hydrophilic nature, react with water and cement particles in the concrete to form calcium silicate hydrates, increasing the density of the CSH phase, and/or pore-blocking precipitates in the existing micro-cracks. The mechanism is analogous to the formation of CSH and the resulting crystalline deposits become integrally bound with the hydrated cement paste, thus contributing not only to a significantly increased resistance to water penetration but also to the healing of the existing damages and cracks. This paper summarizes the results of a wide experimental investigation jointly performed by Politecnico di Milano (Italy), Indian Institute of Technology Madras, Chennai (India) and Universitat Politecnica de Valencia (Spain) to assess the effectiveness of different commercially available crystalline admixtures on the self-healing capacity of cement based materials.

Advances in concrete technology have led to the development of a new class of cementitious composites with improved mechanical and durability properties, named high performance concrete (HPC). Along with improved performance of HPC there is high cement consumption in the production of this type of concrete which leads to certain increases in CO2 emissions. Ecological and environmental benefits support the use of waste glass powder as supplementary cementing material by decreasing the necessity for landfills, by the reduction of non-renewable natural resource consumption, by the reduction of energy demand for cement production (less cement is needed), and by reducing the greenhouse gas emissions. The present research is focused on design of an HPC using different glass waste cullet ground along with sand into powders which have the most promising effect on the properties of concrete and the effectiveness of application of new generation poly-phosphonic superplasticizers blended with PCE based superplasticizer for HPC concrete. Portland cement is substituted at a level of 20% by mass with glass waste powder which gives the improvement of workability and mechanical properties of the concrete what makes glass powder a valuable Portland cement substitute.

A novel technique to upgrade the mortar durability by surface coating layer formation and densification using an electrodeposition method is suggested here. In this technique, the SiO32- ions as key raw materials are applied. Under the applied electric field, they are transported into the pores to react with Ca(OH)2 to promote the additional C-S-H gel formation, which induces the densification of mortar. Besides, the accelerated hydrolytic reaction of SiO32- ions, and the reaction of SiO32- ions in the outer electrolyte with the leached Ca2+ promote C-S-H/silica gel precipitation on the mortar surface. Furthermore, by a comparative experiment, it has been found that this technique can moderately increase the compressive strength and flexural strength of electrodeposited mortar sample. Also, the chloride diffusion into the electrodeposited mortar sample is notably decreased, which demonstrates the effectiveness of this electrodeposition technique in upgrading the durability.

Concrete is the most versatile construction material. However, the image of concrete looks often one of something non-friendly from an environmental point of view. Further developments, “green chemistry” and new techniques, should continue to be introduced into the cement and concrete industry. This will provide distinct alternatives to OPC dominating inside cement market. Simultaneously new scientific and technological breakthroughs are required. One of such additional strategies is based on advanced concrete technology concepts, which enables the reduction of the quantity of cement used in concrete, by combining fillers and various admixtures. Another strategy is based on a new design of the structural component, to evaluate the use of different materials and to achieve an overall reduction of the environmental impacts. This strategy highlights Life Cycle Analysis and Design, Performance Standards for Durability, Environmentally Driven Design and the role of the reinforcement, because the conventional steel reinforcement contributes to environmental footprint as much as the cement in the concrete. Composite materials, including polymer composite reinforcement, non-metallic fibers and the external reinforcement for repair and strengthening, would be widely used in modern construction. Additional benefits of synergy between these different solutions might be realized leading to reduction of more than 50% of environmental load.

Mix-design of self-consolidating concrete (SCC) with construction and demolition concrete waste (C&DW) as recycled aggregates is investigated. The novelty of this paper consists in the possibility of using both fine and coarse high-grade C&DW for the preparation of new SCC. The effects of recycled aggregates on porosity measurements and mechanical investigations combined with time-dependent properties are investigated. A reference SCC mix, with natural aggregates and the same water/powder ratio as SCC with recycled aggregates, is reported for comparison. Results are correlated in an integrated approach to study the feasibility of structural SCC with medium-high mechanical strength. Finally, this work attempts to strengthen the concept of sustainability in civil constructions.