Publications by authors named "Keppert M"

Thermally activated clays (TACs) have been identified as possible supplementary cementitious materials (SCMs). To find a suitable clay and to optimise the activation process, it is necessary to determine its pozzolanic activity. However, the nature of clays is different from that of conventional SCMs.

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One of the biggest challenges in the construction industry in recent times is the mitigation of the environmental impact of this sector, the reduction in dependence on primary raw materials, and the reduction in CO production while maintaining functional properties. Alkaline activation of a number of waste products represents a promising way to achieve the above-mentioned goals, but the availability of a number of waste products changes over time, especially in Europe. While freshwater sediments were in the past widely utilized as an agricultural fertilizer, recent precautions have significantly decreased such application, and thus new destinations must be delivered.

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The rationalization of material flows, together with the utilization of waste raw materials for the production of alternative binders, became a very attractive topic during the last decades. However, the majority of designed materials can be used as a replacement for low-performance products. In this work, the waste materials (brick powder and blast furnace slag) are valorized through geopolymerization to design high-performance material as an alternative to high-performance concrete.

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Self-compaction concrete (SCC) is ranked among the main technological innovations of the last decades. Hence, it introduces a suitable possibility for further utilization of supplementary cementitious materials (SCM) in terms of sustainable development. The aim of the work is the assessment of a new approach to binder design, which takes into consideration the activity of the used mineral additive.

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The growing utilization of various mineral additives in the building industry has caused concern worldwide to reduce the emissions of carbon dioxide from Portland cement (OPC) production. The present paper is focused on the determination of the degree of hydration of blended binding systems based on Portland cement. Blast furnace slag, fly ash, and ceramic powder are used in the study; they are applied by 12.

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Article Synopsis
  • The study investigated the ability of waste brick dust (WBD) to remove lead (Pb) and cesium (Cs) from water, using solutions of 0.1 M and 0.5 M concentrations and two types of WBD.
  • Results showed that the Libochovice-LB WBD was more effective for Pb adsorption due to better structural properties and inner-sphere complexation, while Cs showed weak adsorption and was less effectively removed.
  • The leachability of Pb from WBD was very low (0.001% to 0.3%), but Cs leachability was significantly higher (4% to 12%), indicating that while WBD can adsorb Pb well,
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Lead, a highly toxic element, is frequently present in various solid wastes as well as in industrial effluents. Sorption with a low cost sorbent is a simple way of Pb removal from liquid streams, but stabilization of spent sorbent has to be ensured in order to prevent Pb leaching out and possible environmental contamination. In previous research, ceramic sorbent, generated as waste product in brick industry, was tested as sorbent and proved high sorption capacity for lead.

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Fly ashes generated by power and heating plants are commonly used in the production of building materials in some countries, mainly as partial replacement of cement or aggregates in concrete. The ashes from municipal solid waste incinerators can be applied in a similar way. However, their chemical and mineralogical composition, granulometry and toxic constituents have to be taken into account.

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Phosphorus is one of the predominant impurities in the Hall-Heroult process for industrial aluminium production. The nature of the dissolved phosphorus species in the Na(3)AlF(6)-AlPO(4) system has been investigated by in situ high-temperature (HT) (19)F, (23)Na, (27)Al, (17)O, and (31)P NMR. The combination of these experiments enables to define the presence of PO(4)(3-), AlF(5)(2-) and (AlF(4)-O-PO(3))(4-) anions in the melt, and then the formation of Al-O-P bonding.

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The creation of an experimental group for digitalization of two-dimensional X-ray pictures of bones was the starting point for the application of selected procedures for their computer-assisted analysis. During processing of the picture first the primary digitalized picture was corrected (e. g.

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