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Examination of microstructure of solidification product containing hazardous sludge
(Elsevier, 2016-08-03) Hodul, Jakub; Drochytka, Rostislav
The tests involved with the microstructure evaluation must be also added to the processes which significantly support the evaluation of long-term durability of solidification product (SP). Monitoring the microstructure by analyses such as scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and differential thermal analysis (DTA) it can be assumed according to the new compounds being formed during the hydration whether the hydration products are modified. Moreover, it could also be determined how the pollutants contained in input hazardous waste (HW) are incorporated in solidification product (SP) matrix. Within this work four different types of sludges (S) containing dangerous substances, mainly heavy metals were selected as input hazardous waste (HW) for laboratory preparation of samples of the solidification products (SP) for the microstructure analyses. On the basis of the findings from microstructure analyses it can be assumed whether contaminants contained in input HW, sludges, is immobilized into the matrices of solidification products (SP) by incorporating into the hydration products of SP matrix.
Alternative Evaluation of the grindability of Pozzolanic Materials for Cement Production
(IOP Publishing, 2017-10-25) Dvořák, Karel; Dolák, Dušan
All conventional methods for the evaluation of grindability require a specific grinding instrument. These grinding instruments do not have any other practical use and thus are not very common. This paper focuses on the alternative evaluation of grindability. Inspired by the VTI method used in the coal industry, a new method was created. The first modification in methodology was the use of a planetary mill instead of a porcelain drum mill. Another modification was in the measurement of undersize by means of laser granulometry.
Repairing composite using hazardous waste containing heavy metals
(IOP Publishing, 2018-07-16) Žlebek, Tomáš; Hodul, Jakub; Drochytka, Rostislav
This research deals with the possibility of using hazardous waste in epoxy resinbased polymeric substances. More specifically, it is the use of neutralising galvanic sludge (NGS), which produces as a by-product in the surface treatment of metallic elements. The objective of the research was to incorporate as much as possible of this hazardous waste into a suitable polymeric substance because the further use of this waste is very problematic and is costly to treat and dump. Experiments carried out have shown that homogenisation of this hazardous waste with a suitable epoxy resin results in the coating of all filler particles in the form of waste by the binder and there is no release of heavy metals and other undesirable contaminants. From an ecological point of view, it is, therefore, possible to use the pre-treated neutralising sludge as suitable filler in the polymer-based repairing composite. On the basis of the assessment of the mechanical properties test evaluation, it can be stated that the most suitable seems the application of 40% quantity by weight of this hazardous waste type to be used in the repairing mortar. The perfect distribution of hazardous waste particles in the epoxy matrix was confirmed by the evaluation of scanning electron microscope (SEM) images. The distribution of the individual elements found in the filler was monitored by energy dispersive X-ray analysis (EDX).
Effect of particle size of waste brick powder on the properties of alkaline activated materials
(IOP Publishing, 2018-07-12) Brînduş-Simuţ, Jiřina; Vyšvařil, Martin; Bayer, Patrik; Keppert, Martin; Rovnaníková, Pavla
The properties of alkaline activated brick dust mixed with water glass with a silicate modulus (Ms) of 1.0 were studied in fresh mixtures as well as hardened products in connection with the particle size of the dust. The brick dust (ground waste brick) was separated into 5 fractions according to particle size. The influence of particle size on the rheological properties of the fresh mixtures was studied via measurements of the yield stress and viscosity. The flexural and compressive strengths of the hardened products were determined after storage under laboratory conditions for 7, 14 and 90 days; the influence of 7 days of curing at 65°C on strength was evaluated as well. The microstructure of the hardened products was studied by means of porosimetry and SEM.
The Acoustic Emission Parameters Obtained during Three-point Bending Test on Thermal-stressed Concrete Specimens
(Elsevier, 2017-06-02) Topolář, Libor; Kucharczyková, Barbara; Kocáb, Dalibor; Pazdera, Luboš
Fire response of concrete structural members depends on thermal, mechanical, and deformation properties of concrete. These properties vary significantly with temperature and also depend on the composition and characteristics of the concrete batch mix as well as heating rate and other environmental conditions. Concrete structures could be exposed to extreme temperature conditions. Examples of such conditions are concrete foundations for launching rockets carrying spaceships, concrete structures in nuclear power stations or those accidentally exposed to fire, for instance in the case of tunnel fires. This paper analyses acoustic emission signals captured during three-point bending test on thermal-stressed concrete specimens. The method of acoustic emission is an experimental tool suitable for monitoring the failure processes in materials. The typical parameters of acoustic emission signal were identified during the acoustic emission records for different concrete specimens to further describe the under-the-stress behaviour and failure development. The amount of crack growth was continuously monitored using four acoustic emission sensorsmounted on the specimens.

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