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In a time when the attention paid to identifying the possibilities of reducing problems due to urban pollution is increasing, the construction industry has a lot to gain if it aligns itself with the new trends of sustainable development in the field. In this context, the objective of obtaining a concrete with self-healing properties of cracks is more than appropriate, becoming a sustainable alternative for reducing the maintenance costs of transport infrastructure by increasing their operating time and by decreasing the need for the volume of repair and maintenance works, thus indirectly contributing to the reduction of environmental pollution. Preliminary results obtained using a cementitious composite with waterproofing admixture content by mass crystallization are encouraging by identifying the existence of an autonomous healing degree (closure of cracks with average opening 20-40 µm) in a proportion of at least 65% after only 96 hours of exposure in a wet-dry environment, respectively and of at least 96% after 480 hours of conditioning. The degree of novelty and value of this research is mainly due to the approach of this type of composite produced by adapting the general principles to local raw materials, including the use of specific industrial waste and by-products available in Romania (fly ash and limestone slurry).

The use of waste from industrial activities is of particular importance for environmental protection. Fly ash has a high potential in the production of construction materials. In the present study, the use of fly ash in the production of geopolymer paste and the effect of Fe2O3, MgO and molarity of NaOH solution on the mechanical strength of geopolymer paste are presented. Samples resulting from the heat treatment of the geopolymer paste were subjected to mechanical tests and SEM, EDS and XRD analyses. Samples were obtained using 6 molar and 8 molar NaOH solution with and without the addition of Fe2O3 and MgO. Samples obtained using a 6 molar NaOH solution where Fe2O3 and MgO were added had higher mechanical strengths compared to the other samples. [ABSTRACT FROM AUTHOR]

Both Circular Economy and Sustainable Development are concepts that focus on resource efficiency. This involves a complex waste management process with a high degree of recycling and recovery. Rapid population growth and urbanization in developing countries have led to large amounts of solid waste and, consequently, increased environmental degradation of the environment. Designing resilient, sustainable materials and buildings by using recycled materials or industrial by-products, which can replace some or all of the cement, leads to the development of a sustainable, low-carbon economy and furthermore to the conservation of natural resources. Industry is developing at an accelerated pace, consequently the development of modern construction materials in the economic world is more than necessary. The aim of this research is to present preliminary results regarding the design of the alkali-activated fly ash-based geopolymer paving blocks produced using Romanian local raw materials, to present several parameters that affect their mechanical properties and to assess their intended use in terms of legislation. [ABSTRACT FROM AUTHOR]

The term “geopolymer” was originally introduced by the French chemist Davidovits, representing a wide range of anorganic materials. According to him, among the nine different classes of geopolymers, geopolymer concrete is of particular interest, consisting of materials containing aluminosilicates that could be used to completely replace the amount of Portland cement in ordinary concrete. The aim of this study is to present relevant data in the field of alkali-activated geopolymer materials regarding the production of this type of materials using both ambiental and heat curing and studying the differences between the two procedures. [ABSTRACT FROM AUTHOR]