Advanced Materials Research Vol. 923

Abstract: Protection of masonry and constructions of buildings against water and moisture is an important part of building industry. Contribution deals with problems of moisture, its classification and moisture level on the constructions. The chemical grouting method for protection of autoclaved aerated concrete masonry against capillary moisture via treatment by using the hydrophobic grouting solution Freezteq DPC System is described in this contribution.

Abstract: The sample of not sustainable way of reconstruction of small but important and significant structure of Plecnik ́s foot bridge located at Prague Castle area is discussed at this contribution. The structure was strongly impaired 10 years after complex reconstruction. This damage and degradation was caused mainly due to malfunctioning of new waterproofing and frozen water in the drainage system of the bridge deck.

Abstract: The geocement-based coatings for repair and protection of concrete structures of which the installations for production of biogas, water supply and sewage water disposal pipelines are made have been developed and have been tried in practice. Resistance of the developed coatings in an aggressive environment (5 % solution of ammonium sulfate) as well as basic physico- chemical processes taking place during interaction of the ammonium salts with the geocements have been studied and the results are discussed. A conclusion was made that among other geocement hydration products which can resist attacks of sulfate-ammonium ions, faujasite, chabazite and mordenite had the highest resistance, whereas heulandite and hydrosodalite have the lowest resistance. This assumption is in agreement with the outcomes of other researchers. The results of examination show that the ammonium-containing zeolites have been synthesized within the hydration products, these were: ammonium analcime, (NH₄, Na)-zeolite-E, zeolite a, zeolite ZK-21 and NH₄-zeolite-W. The coated concrete (a geocement (Na₂O×Al₂O₃×6SiO₂×30 H₂O)-based coating)) is found to be corrosion resistant in aggressive environment containing ammonium sulfates: its coefficient of resistance is 1.01, being at an age of 30 days by 1.2 times higher compared to that of the uncoated concrete of the same age.

Abstract: The contribution deals with the possibilities of measuring the sound absorption coefficient of concrete panels. On the example of the modified concrete shows one of the possible methods that could be used to check for changes in the case of acoustic properties of restoration of the damaged panels. The issue of evaluation of the sound absorption coefficient is quite complex and difficult in the interpretation of the results, primarily due to the impact of the size of the tested element and parasitic interference in the surrounding environment.

Abstract: Production of artificial aggregates is one of the suitable ways how to use the maximum ratio of fly ash in construction materials. Subsequent use of aggregates is directed in addition to various embankments, filter layers and also for lightweight concrete. Concrete can be used wherever required low weight while maintaining the necessary strength. The contribution is geared to verify the applicability of newly produced artificial aggregates from different types of fly ash for standard concrete.

Abstract: Physico-chemical processes of hardening of a cement stone are accompanied with shrinkage is known to result in crack formation, loss of concrete structure integrity and finally, to shorter service life. These drawbacks make problems in using traditional portland cement based mortars for joint grouting and crack repair in concretes. Known-in-the-art solutions based on calcium aluminate cements are also not efficient due to high cost and instability of cement stone hydration products over time in various service conditions. Shrinkage-compensating alkali activated slag cement mortars are proposed to solve the problems connected with crack repair and joint grouting. They are simple in preparation and application and have a set of high physico-mechanical properties, excellent durability and reasonable cost.

Abstract: In the Czech Republic, the deicing salt resistance is determined through the scaling from the sample exposed to 3% NaCl solution after prescribed numbers of frosting-defrosting cycles (see ČSN 731326). The surface layer of concrete is contacted as the first with aggressive substances and is an entrance gate for unwanted ones. Its quality is not only affected by the proposed mix and procedure of placing fresh concrete with following curing, but also by the final modification performed with various types of smoothers.

Abstract: In recent years, textile reinforced concrete (TRC) is at the beginning of industrial production mainly in Germany and relates especially to facade panels and concrete footbridges. The subtle panels with a minimum thickness of coverage layer can be designed due to the textile reinforcement, which is resistant to corrosion. Furthermore, a long durability is expected in case of these structures. The textile reinforcement with the fine-grained ultra-high performance concrete (UHPC) enables to produce concrete elements with a minimum thickness. Therefore, the concrete element with up to 70 % lower weight compared to element with conventional reinforcement can be produced and significant environmental savings can be achieved (reducing the consumption of non-renewable raw materials, transport energy, reduced dead load acting on the supporting structure, etc.).

Abstract: This paper presents reSBToolCZ, the first multicriterion assessment tool for existing buildings and their refurbishments which takes into account their cultural-historical value. The assessment scheme comes from a general platform of SBToolCZ and adjusts selected criteria in a way that the assessment reflects cultural-historical value of buildings and recognizes it as a quality that is an inseparable part of sustainable development..

Abstract: Many structures resting on pile foundations, which are surrounded by water in the soil for decades or centuries. In the context of status explorations or assessments questions arise concerning their conservation status and their durability. The paper presents the results of extensive in situ studies and laboratory tests, which were performed on older wooden pile foundations of port facilities, bridges and building foundations in the framework of planning of maintenance measures. In the focus of this work are studies on the biotic attack to the woods and its effect on the density and strength characteristics of the piles. Inter alia, the investigations have revealed that the wood under the said anaerobic conditions suffers deterioration due to bacterial attack, rarely by higher fungi. As discovered by microscopic investigations on thin sections, the bacterial attack appears as a partial degradation in the individual wood cells, especially in the middle lamella of the late wood cells and the dots. As indicated by the results of the of the density and strength test results, the bacterial attack is - compared to fungal attack - a very slow but steady process. It causes also strength reduction of the woods and losses of the load bearing capacity of the structures, and has to be taken into account in the static assessments.