In less than one century concrete has become the most widely used construction material over the world. In less than half of century it is difficult to imagine a concrete totally without polymers. An ...implantation of polymers into concrete has taken effect in the form of Concrete Polymer Composite: C-PC. Since then (1975) the development of new concrete classes have been ongoing: C-PC = PMC + PCC + PI + PC, where PMC Polymer Modified Concrete (polymer cont. < 1% concrete mass); PCC Polymer Cement Concrete (> 1% concrete mass); PIC Polymer Impregnated Concrete (3-8% concrete mass), PC Polymer Concrete (8-12% concrete mass). Over the time the role of polymers have been extended and it is covered by polymer with additional preposition: polymers on concrete (overlays, coatings, waterproofing and bounding materials). All those polymer composites have been found irreplaceable application in concrete repairing industry. It is enough to say that in ten parts of the European Standards, EN 1504, the category “polymer” can be found 73 times, and that is a proof of the big significance of this material in the repairs and protection of concrete. Just for comparison reason, the term “cement” appears only 59 times in all parts of the EN 1504. Indeed, if repaired concrete is higher class then repairing material should content more polymer. The justification belongs to the adhesion, which is a fundamental challenge for concrete repair. But also short time to exploitation readiness and many others polymer composites advantages are taken into consideration. In the paper the question: how polymers enhance concrete repair performance? is discussed. The repair rules and methods versus polymer repair materials will be considered.
The repairs of building structures are inevitable and indispensable. Repairs are used to restore or maintain the usability of existing facilities, often contributing to the extension of their ...expected service life, increasing the sustainability of building resources. Given that conservation rules are observed, repairs are also used to save monuments. The concept of repair durability brings to the foreground the durability of the repaired structure (after repair): what service life has been obtained/recovered as a result of the repair. Based on the available data (limited set), a generalised distribution function of repair durability was developed, with a disappointing course. This, however, applies (necessarily) to the past. Significant progress was shown to have been achieved in the theoretical and technical fundamentals of technical repair measures. In this situation, a prognostic distribution function was also designed for future repairs according to EN 1504. A rule of thumb called estimating concrete repair durability, CRD was proposed. The risk associated with estimating the durability of repairs was indicated. A reason for optimism is that proactive monitoring of the condition of the structure and, consequently, management of the repair strategy allows to reach the designed life of the structure.
The laboratory testing of the construction materials and elements is a subset of activities inherent in sustainable building materials engineering. Two questions arise regarding test methods used: ...the relation between test results and material behavior in actual conditions on the one hand, and the variability of results related to uncertainty on the other. The paper presents the analysis of the results and uncertainties of the simple two independent test examples (bond strength and tensile strength) in order to demonstrate discrepancies related to the ambiguous methods of estimating uncertainty and the consequences of using test methods when method suitability for conformity assessment has not been properly verified. Examples are the basis for opening discussion on the test methods development direction, which makes possible to consider them as 'sustainable'. The authors address the negative impact of the lack of a complete test models taking into account proceeding with an uncertainty on erroneous assessment risks. Adverse effects can be minimized by creating test methods appropriate for the test's purpose (e.g., initial or routine tests) and handling with uncontrolled uncertainty components. Sustainable test methods should ensure a balance between widely defined tests and evaluation costs and the material's or building's safety, reliability, and stability.
The research assesses the effect of selected type II additives on concrete carbonation. Siliceous fly ash, FASi, is used as a cement component or cement replacement in concrete; ground granulated ...blast furnace slag, GGBS, is used as a cement component; fluidised bed fly ash, FFACa, is used as a cement replacement; calcareous fly ash, FACa, is used as a fine aggregate replacement; and, silica fume, SF, is used as a cement or fine aggregate replacement. The results show that waste mineral additives increase the depth and rate of carbonation, while extending water curing time increases the resistance to carbonation of concrete containing additives, significantly in GGBS cement and concretes with w/c ratio above 0.35. The results show that in the case of concrete with mineral additives, such as ash and slag, the course of the initial water curing of concrete is a very important factor influencing resistance to carbonation. The application of waste mineral additives to concrete should include the lowest possible w/c ratio and the lengthiest possible water curing, immediately after the commencement of construction activity.
Active fire protection systems are critical elements of good process safety. Among them, gaseous extinguishing systems provide quick, clean suppression and prolonged protection due to long retention ...process of the gas. Standard design methods do not provide sufficient tools for optimisation of the retention process, thus the necessity for development and validation of new tools and methods—such as Computational Fluid Dynamics (CFD) simulations. This paper presents a simplified approach to CFD modelling, by the omission of the discharge phase of the gas system. As the flow field after discharge is stable and driven mainly by the hydrostatic pressure difference, buoyancy and diffusion, this simplified approach appears as an efficient and cost-effective approach. This hypothesis was tested through performing CFD simulations, and their comparison against experimental measurements in a bench scale in a small compartment (0.72 m3), for six mixtures that differ in their density. Modelling the retention of the standard IG55 mixture was very close to the experiment. Modelling of mixtures with a density close to the density of ambient air has proven to be a challenge. However, the obtained results had sufficient accuracy (in most cases relative error <10%). This study shows the viability of the simplified approach in modelling the retention process, and indicates additional benefits of the numerical analyses in the determination of the fire safety of protected premises.
A theoretical model for predicting the carbonation depth of concrete is presented. The proposed, experimentally determined model describes the carbonation depth as a function of the time of exposure, ...the water-binder ratio, and early-age curing conditions. The result is a new mathematical formulation of carbonation depth as a hyperbolic function of time, which assumes that the depth of the carbonation is ultimately limited as the concrete pores fill with carbonation products. Tests were carried out for 6 years in a natural atmospheric concentration of CO2 in an urban-industrial environment. The results showing the carbonation depth for concrete using different types of cement are used to derive equations to predict carbonation depth. It is expected that the resulting equations can be applied to the prediction of the concrete cover thickness for reinforcement in concrete structures. PUBLICATION ABSTRACT
Sustainable Construction as a Research Area CZARNECKI, Lech; KAPRON, Marek
International Journal of the Society of Materials Engineering for Resources,
2010, Letnik:
17, Številka:
2
Journal Article
Odprti dostop
Sustainable development is one of the leading civilization ideas. This term means such a development that satisfies the present needs without a limitation of the possibility of satisfying the needs ...in the future. Sustainable development in construction is particularly important, as this branch of the industry is consuming enormous amounts of mass and energy. A new research area has been created by this idea. The new fields of investigation are involved with material, energetic, and environmental conditions, but also with such topics as protection against noise and the methods of the evaluation of the efficiency of waste materials storage. Implementation of the idea of sustainable development in the construction industry will be a source of scientific and engineering inspiration for many years to come.
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