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The requirements for the stringent implementation of sustainability criteria for development, considering the worldwide context of massive pollution, the need to preserve the natural resources and the urge for environmental protection emphasize the drive for developing high-performance building materials, both in terms of raw materials used and low production costs, as well as related to their physical-mechanical and durability characteristics along the lifespan of the structure where used. Consequently, stimulating the intrinsic self-healing ability of cementitious composites, aiming both, the increase of durability and structural lifespan expansion with simultaneous reduction of repair and maintenance activities, represents an innovative, highly explored, contemporary global research direction. This paper presents the preliminary direction concerning the theoretical investigation and the applicative development of an intelligent addition of reactive grains with polymeric encapsulation, for cementitious materials, namely for optimizing their durability by stimulating the long-term continuous hydration.

Determining the concrete compressive strength is an important issue for both existing and new constructions. Existing constructions, subject to retrofit and / or extension, require the determination of concrete compressive strength in specific elements, for the realistic and correct evaluation of the structure in terms of overall strength and stability. New constructions, on the other hand, may face situations when there are doubts about the quality of the delivered concrete, the casting operations or other technological or design flaws. The correct determination of the actual concrete compressive strength may be essential in evaluating the structural health and identifying the optimum design and technological solutions for the evaluated building. Non-destructive methods for determining the concrete strength are, by definition, minimally invasive methods, namely they do not affect the integrity of the structure. This paper provides a comparison between the combined non-destructive method and the destructive, classical method for compressive strength determination.

The demand for concrete and also for the current infrastructure facilities development is experiencing worldwide exponential growth. Environmental issues associated with the production of Portland cement are very well known and therefore they are carefully monitored, especially in terms of CO2 emissions released into the atmosphere. Therefore, it is essential to find alternatives namely creating environmental-friendly materials. The particular procedure of alkali-activating the fly ash, combined with a specific alkaline activator, offers possibilities for the development of a material with cementitious-like properties. Large quantities of fly ash, resulting from electricity production in Romania, open new opportunities for studying and developing Geopolymer composites with local materials.

he today Romanian infrastructure, road and civil, evaluated both in terms of existing or identified need of structures (buildings of different importance class and with different functionalities, roads, highways, viaducts and bridges, etc.), represents an essential part, with major and synergetic role in the society life and evolution. As consequence, its preservation and future development are major topics of interest in order to ensure the progress of Romanian space as part of European Union and European Community. Identifying the optimum solutions and the best materials for this major goal should become priorities for all parties involved in the process: research and industry, academia, economic and political entities. Engineered Cementitious Composites (ECCs) are therefore mentioned as a new type of cement-based composites, with unique features and superior performances, which can be developed, tailored and adjusted according to specific needs, destination and structural design. This paper presents a general introduction of them, their potential towards a sustainable infrastructure and also a review of ECC development in INCERC Cluj, with local raw material and with respect to some proposed fields of application.

The paper presents the experimental results obtained for bending strength parallel to the fibers of a beam element made of hardwood (deciduous) glued laminated timber. At the same time, tests were carried out to determine the physico-mechanical characteristics of the wood specimens, in order verify the wood species.

Romania’s recent joining of the European family implies a fast upgrading of all evaluation references for every direction concerning life evolution and society development, in close correlation with the European ones. In accordance with the European strategies, implemented starting with 2000, sustainability is set as a key priority, governing all further development axes. Innovation, one of the foundation pillars of durability (environmental protection and non-renewable resources management) can be successfully implemented in all fields of activity. For instance, the path to a sustainable infrastructure could include innovative building materials, designed and developed by means of new technologies and of the latest information, as well as the use of additions (industrial waste / by-products), which could contribute to the improvement of their characteristics and performance. The aim of this paper is to present a general overview of the scientific demarches developed in the topic of Material Science, where innovation is achieved by identifying the re-conversion options for wastes and by-products from industrial processes, as mineral additions for cement-based composites.

In the practice of prefabricated concrete structures considerable surfaces of intermediate floors are constructed using double floor systems with prefabricated bottom layer and upper layer. This second layer is cast on site. The quality of the prefabricated concrete is often of superior class with respect to the monolithic layer. In the service state of the double floor system, important compressive stresses appear in the upper concrete layer. On the other hand, the bond quality between the concrete layers cast in successive stages raises questions especially in the case of hollow core floor units with no connecting reinforcement in-between. The paper presents results of the numerical models prepared for double floor elements having different thicknesses for the top and bottom layers, subjected to bending. Three situations have been studied: stepped top surface of the prefabricated slab with no connecting reinforcement, broom swept tracks on the prefabricated slab with no connecting reinforcement and broom swept tracks on the prefabricated slab with stirrups connecting the concrete layers. For each situation two different ratios of the thicknesses of the layers have been considered. The results are emphasizing the critical regions of the elements, the differences in crack development and in the behaviour resulting from surface preparation and use of connecting reinforcements.

Developing non-destructive methods (NDT) that can deliver faster and more accurate results is an objective pursued by many researchers. The purpose of this paper is to present a new approach in predicting the concrete compressive strength through means of ultrasonic testing for non-destructive determination of the dynamic and static modulus of elasticity. For this study, the dynamic Poisson’s coefficient was assigned values provided by technical literature. Using ultra-sonic pulse velocity (UPV) the apparent density and the dynamic modulus of elasticity were determined. The viability of the theoretical approach proposed by Salman, used for the air-dry density determination (predicted density), was experimentally confirmed (measured density). The calculated accuracy of the Salman method ranged between 98 and 99% for all the four groups of specimens used in the study. Furthermore, the static modulus of elasticity was deducted through a linear relationship between the two moduli of elasticity. Finally, the concrete compressive strength was mathematically determined by using the previously mentioned parameters. The accuracy of the proposed method for concrete compressive strength assessment ranged between 92 and 94%. The precision was established with respect to the destructive testing of concrete cores. For this research, the experimental part was performed on concrete cores extracted from different elements of different structures and divided into four distinct groups. The high rate of accuracy in predicting the concrete compressive strength, provided by this study, exceeds 90% with respect to the reference, and makes this method suitable for further investigations related to both the optimization of the procedure and = the domain of applicability (in terms of structural aspects and concrete mix design, environmental conditions, etc.).

Cement-based composites have proved, over the time, certain abilities of self-healing the damages (cracks and especially microcracs) that occur within their structure. Depending on the level of damage and of the composite type in which this occurs, the self - healing process (SH) can range from crack closing or crack sealing to the stage of partial or even complete recovery of material physical - mechanical properties. The aim of this paper is to present the general concept of Engineered Cementitious Composites (ECCs) with their unique properties including their self-healing (SH) capacity, as an innovative direction for a global sustainable infrastructure. The experimental steps initiated for the development in Romania of this unique category of materials, using materials available on the local market, are also presented.

Year after year we witness the negative effect of water over buildings, caused by direct or indirect actions. This situation is obvious in case of old, historical building, subjected to this aggression for a long period of time, but new buildings are also affected. Moisture in building materials causes not only structural damage, but also reduces the thermal insulation capacity of building components.Materials like plasters or paints have been used historically for a long period of time, fulfilling two basics functions: Decoration and Protection. The most acute demands are made on exterior plasters, as they, besides being an important decorative element for the facade, must perform two different functions simultaneously: protect the substrate against weathering and moisture without sealing, providing it a certain ability to “breathe” (Heilen, 2005). In order to accomplish this aim, the first step is to understand the hygrothermal behavior of coating and substrate and define the fundamental principles of moisture transfer; According to Künzel’s Facade Protection Theory, two material properties play the most important role: Water absorption and Vapor permeability.In the context of recently adoption (2009) of the “harmonized” European standard EN 15824 – „Specifications for external renders and internal plasters based on organic binders”, this paper deals extensively with the interaction of the two mentioned above properties for the coating materials, covered by EN 15824.