Advanced Materials Research Vol. 923

Abstract: The paper presents the results of an experimental comparison of essential moisture characteristics of two types of sandstone, intended for the outdoor use. In addition to traditional physical properties, dynamics of absorption of both materials in its original condition as well as after the hydrophobization were investigated. The aim of the experiment is to determine the most suitable material variations for the reconstruction.

Abstract: Roofing slate is a traditional natural material for roofing and other construction applications in various types of buildings. The paper deals with both traditional methods of mineralogical-petrographic analysis as well as completely new methods (X-ray CT) rendering fast and reliable determination of qualitative parameters and potential slate durability in building constructions. A mutual combination of the methods represents a rapid, effective and modern alternative to lengthy laboratory tests to determine physical-mechanical properties of newly used roofing, especially in historical buildings.

Abstract: The aim of the contribution is to present the results of research focused on cement mineralogical composition changes and their influence on physical-mechanical properties of sandstones. Three types of Czech sandstones were tested during this experiment Hořice, Kocběře and Božanov. The sandstone samples were treated in the climatic chamber in order to simulate weathering processes that are typical for winter period in Prague. The influence of road salts was also taken into consideration. For the purposes of mineralogical changes determination the sandstone cement was separated and subsequently analyzed using X-Ray diffraction a DTA/TG analysis. The physical-mechanical properties such as e.g. uniaxial compressive strength, water absorption and open porosity were determined before and after the climatic treatment to enable evaluation of the influence of weathering processes.

Abstract: Assessment of suitability of mortar intended for reconstruction based on their characteristics, namely basic, hygric and mechanical parameters, chemical analysis and frost resistance, is presented in this paper. Properties of the load bearing structure as well as natural factors were also taken into account in assessing the suitability of the used mortars. Comparative measurements with original historic plaster are done as well. On the basis of the experiments performed, it can be concluded that not only mortar properties but also environment conditions and technology of application as well as load bearing structure characteristics have a great importance to the service life of the repaired parts of historical buildings.

Abstract: The experimental, in-situ and laboratory research has manifested a relatively large variance of the physical and mechanical characteristics of historical masonry found e.g. within a masonry wall, a massive masonry pillar etc. Artical presents the evaluation of the experimentally determined physical and mechanical characteristics of masonry members and the binder obtained by sampling specimens and by non-destructive measurements relies on the application of appropriate probabilistic methods.

Abstract: How perhaps everybody from us must notice the degradation of buildings is omnipresent and it doesnt avoid even historic buildings that many times belong to our national heritage. Most of historic buildings were built from the most common material of that time, i.e. from full burnt bricks. But these bricks werent as similar as eggs are each other how it is ordinary for materials at these days. Within our research project the tests that determine the ranges of properties of the historic bricks were performed. The tests of mechanical properties and particularly damp tests were performed. The goal of our research was also the comparison of surface finishing of full burnt bricks from the point of view of diffusion transport of moisture. This paper summarizes valuable results that show what range of properties of historic bricks we can expect and how we should behave towards these old buildings in our best.

Abstract: In this paper are explored the changes of pore structures of mortar with pozzolanic admixture exposed to aggressive environments, namely 5% wt. sodium sulphate solution. Influence of non-flowing sulphate solution on the test specimens were determined in dependence on the different type of cement and used minced clay brick as pozzolanic admixture. Attention is also paid to the properties of the individual components of the mortar. From the results obtained follows that the additive of minced clay bricks has positive impact on the sulphate resistance.

Abstract: The experimental research of failure mechanism of stone columns made of coursed masonry of regular sandstone blocks and coursed masonry of irregular (freestone) blocks under concentric compression and the research of the performance of non-reinforced as well as CFRP-reinforced stone columns completed to-date pointed out the necessity of a different approach to the assessment of the load-bearing capacity, or residual load-bearing capacity, of masonry composed of stone blocks.

Abstract: It is often necessary to determine strength of concrete (Normal-weight, High-performance and Light-Weight) in the structure. To determine strength, ultrasonic pulse method is used. However, the basic condition of its effective use is existence of relations between velocity of ultrasonic pulse propagation and strength. These relations are elaborated for normal weight concrete in great extent. However, for other types of concrete, relations for determination of strength on the basis of ultrasonic pulse velocity are stated in technical literature and their practical applicability could be questioned. The paper gives analysis of such relations from the point of view of practical applicability for determination of parameters of concrete built in a structure.

Abstract: The paper presents the results of research aimed at modifying the composition of the cement-bonded particleboards. These materials can be used as a suitable finish surface treatment among others for renovations of not only older buildings. Specifically, a problem of analyzing of selected and actually produced alternative raw materials in connection with previous results and findings. The effect of pretreatment with suitable grinding equipment was tested. Furthermore, it was the use of thermal methods for the quantification of the constituents of the analyzed material. In terms of subsequent modification of the composition of cement-bonded particleboards outputs can be found the outputs stated in the article as essential and beneficial for continuing research. The presented results also provide details of earlier findings made in this area.