Slump Loss of Concrete Based on RCA and Prepared by Specific Mixing Approach

Concrete is a dynamic material and its consistency changes with time, having impact on technological processes at working site. It is expressed due to slump loss - the reduction in slump from the time of original batching to the point when concrete is discharged from a truck mixer. Two kinds of additives (fly ash and recycled concrete powder) were tested to find their potential to improve the performance of recycled concrete aggregate in concrete, while the principle of triple-mixing method was adopted. Slump loss was evaluated based on measurements taken at 0, 45, and 90 minutes after mixing. The kind of aggregate, as well as kind of powdery material for coating the coarse fractions play significant role for the slump loss. Mixtures with fly ash as coating material achieved the biggest slump loss for both types of aggregate. The recycled concrete powder is well acceptable having similar impact on the slump loss as the cement has. When the NA is changed to RCA, the slump loss is higher and depends on material used for coating

THE INFLUENCE OF HOTMELT PUR GLUES ON QUALITY AUTOMOTIVE LAMINATED TEXTILES

katedra: KTM; rozsah: 74V dnešní době kladou spotřebitelé stále větší požadavky na kvalitu výrobku a proto i tomuto tématu se musí více věnovat výrobci automobilových textilií a splňovat stále přísnější požadavky automobilového průmyslu. I tato práce se bude zabývat technologií ovlivňující kvalitu textilií a nosičů v interiéru automobilu. Práce je rozdělena do dvou částí. V první teoretické části jsou popsány možné technologie lepení v JCFS, principy lepení a lepidla využívaná k lepení textilií pro automotive. V druhé experimentální části bylo vyrobeno několik vzorků na nichž bylo prováděno testování různými metodami, tak abychom porovnali zesítění lepidla a jeho závislost na lpění. Výroba vzorků, testování lpění a bodotávkem bylo realizováno v provozu a laboratořích JCFS. Testování infračervené spektroskopie proběhlo na TZU Brno.In the view of the fact that consumers place more demands on the quality, the producers of the automotive textiles have to pay attention to this issue and has to strict fulfill the higher demands of automotive. Therefore in this thesis is paid the attention to the technology that could have influence on the quality of the textile and back panels in the interior of car. The thesis is split into two parts. In the first part are described technologies of lamination used in JCFS, principles of gluing and glues used for the gluing of the automotive textiles. In the second part have been produced samples and on them has been done testing with different methods. The aim was to compare the polymerization of the glue with the dependence on the adhesion. The production, testing of the adhesion and melting point has been realized in the production plant and lab in JCFS. Testing of the infrared spectroscopy has been done in TZU Brn

Characterization of Sludge From Iron Ore Processing and Properties of Mortar Prepared by Full Replacement of Natural Silica Sand

This paper focuses on the use of sludge, which is currently a landfilled sand-like material left over from the processing of iron ore (IOP), representing an environmental burden. The incorporation of the material into some building mixtures like mortar or concrete can bring both environmental and technical benefit through the improvement of some properties of final mixture. Through the realization of the experiment programme, the authors have contributed to the knowledge about IOP and have determined the impact of this material on the properties of mortar mixture. This material is characterized using chemical, mineralogical, and granulometric analysis and then applied as 100% replacement of silica sand in standard mortar mixture. Basic physical-mechanical parameters (water demand, flexural strength, compressive strength) were tested. For the strength characteristics, both the samples with IOP sludge and samples with standardized sand (reference sample) were subjected to testing for a long-term period (14, 28, 270, and 365 days). Moreover, the capillary moisture was measured for 28-day old samples. Mortar prepared with IOP sludge shows lower compressive strength compared to the reference mixture throughout the overall time development, although the values themselves are sufficient for practical application. The flexural strength was found to be even better. The performance of the IOP sludge can be deemed as promising for practical applications when used in cement mortar