Behaviour of Cement Composites with Lightweight and Heavyweight Aggregates at High Temperatures

This paper presents new results of the research of the influenceof individual input components done on the behaviour of cementbased composite materials exposed to high temperatures. Anew approach of this research lies in combining a fraction ofbasalt fine aggregate and an aggregate base on expanded clayfor a composite material with lower volume weight and higherstrengths and a resistance to high temperatures. In the field ofdispersed reinforcement, new polypropylene fibers treated bylow temperature plasma were tested. Degradation of the structureof designed mixtures was evaluated by comparing densitychanges, mechanical and acoustic properties before and afterexposure to high temperatures. An optical microscope was usedfor determining the width of cracks caused by a thermal load.The contribution of this research was the use of non-destructivemethods for diagnostics of quality and properties of designedconcrete mixtures exposed to high temperatures

Utilization of Alternative Raw Material Sources from Agriculture for the Production of Insulating Materials

Jiri Zach, Jiri Brozovsky, Albinas Gailius Utilization of Alternative Raw Material Sources from Agriculture for the Production of Insulating Materials Conference Information: 8th International Conference on Environmental Engineering, MAY 19-20, 2011 Vilnius, LITHUANIA Source: ICEE-2011 - International Conference on Environmental Engineering Book Series: International Conference on Environmental Engineering (ICEE) Selected papers ISSN: 2029-7106 print / ISSN 2029-7092 online ISBN: 978-9955-28-831-2 CD Year: 2011 Publisher: Vilnius Gediminas Technical University Press Technika Pages: 461–464 View full text in PDF format Abstract Thermal insulating materials based on natural fibres currently represent a progressive direction in the area of thermal insulations, particularly from the viewpoint of sustainable development in the area of the production of building materials and construction because it concerns materials based on an easy-renewable and locally available raw material base. In existing constructions, these materials may well replace other thermal insulating materials (e.g. EPS or mineral wool), which are more demanding in terms of energy and raw materials (Zach and Hroudova 2010b). The main use of these materials is primarily in so-called healthy constructions, i.e. in constructions where traditional construction technologies and natural construction materials are used which by their thermal moisture behavior is close to the demands of the human body. From the viewpoint of utility properties, insulating materials on the basis of natural fibres have very good thermal-insulating properties, good mechanical properties and low eco-toxicity (Zach and Hroudova 2010a; Uihlein, and Ehrenberger et al. 2010). The article addresses the complex evaluation of the production of thermal insulating materials on the basis of natural fibres, mainly flax and hemp. According to implemented measurements it was find out, that insulating materials on the basis of natural flax and hemp fibres dispose of very good thermal insulating properties. Measured values of thermal conductivity of test specimens range between 0.0368 and 0.0419 W.m-1.K-1 (in dependence on bulk density and type of fibres). Next finding was that specimens with higher content of flax fibers have better thermal insulating properties comparing to samples with higher amount of hemp. Keywords: thermal insulating materials, thermal conductivity, natural fibres, technical hemp, flax, eco-toxicity, healthy constructions, renewable row materials

Estimation of initial elastic properties of 2D homogenised masonry model based on tensor scale indices

The paper discussed numerical approach for an estimation of initial elastic material properties for homogenised models of masonry. The tensor scale parameter is utilised. The paper discusses the principles of the use of the tensor scale for such task and it also discusses current limitations of the procedure. A numerical example is provided to illustrate the practical use of the proposed method