Centrum AdMaS - VP1 - MSH

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Long-term durability of cement-bonded particleboards with modified composition by waste dust
(CEMC - České ekologické manažerské centrum, 2021-12-01) Melichar, Tomáš; Bydžovský, Jiří; Dufka, Amos
This paper presents research on long-term behaviour of cement-bonded particleboards exposed to adverse conditions. The boards were subjected to frosting / defrosting cycles, up to 300 cycles. Specifically, 100, 200, 300 cycles were performed at the age of 28 days, 6 months, 12 months, 18 months and 24 months. Compositoin of the particleboards was modified by by-product, which has its origin in production of cement-bonded particleboards. Dust from cutting and grinding of the particleboards was used in amount of 7% as a partial substituent of cement (6%) and spruce chips (1%). The goal of presented research is the assessing the effect of adverse conditions at different age of cement-bonded particleboards (with modified composition), when attention is paid to mechanical properties and microstructure, respectively. Bending strength, modulus of elasticity in bending, transverse tensile strength perpendicular to the plane of the board and microstructure (SEM) were studied with respect to the changes in time (up to 2 years).
Immobilization of Heavy Metals in Natural Zeolite-blended Cement Pastes
(Elsevier, 2016-09-26) Vyšvařil, Martin; Bayer, Patrik
This paper deals with the investigation of efficiency of natural zeolite-blended cement pastes for the immobilization of heavy metals. Natural zeolite was used to partially replace ordinary Portland cement (OPC) at rates of 0% and 20% by weight of a binder and soluble heavy metal salts were added to a mixing water in an amount of 1% and 5% by weight of the binder. The flexural and compressive strength of the cement pastes were investigated, while the leachability of the heavy metals was determined. Additionally, scanning electron microscopy was performed to investigate the microstructure of the cement pastes, while the pore size distribution was analyzed with mercury intrusion porosimetry. The results indicated that the flexural and compressive strengths of the pastes containing 20 wt.% of natural zeolite were higher than those with OPC alone. It was also found out that the effectiveness in reducing the leachability of Ba, Cd, Cu, Ni and Pb was better for the natural zeolite-blended cement pastes.
The microstructure of a cement composite based on a secondary raw materials
(IOP Publishing, 2018-07-16) Figala, Petr; Drochytka, Rostislav
Waste management and its use as a secondary raw material is a matter that is being given increasing attention. Such raw materials also include waste products from the energy industry or municipal waste disposed of from the recycling process. This study explores the use of secondary raw materials in specific cement–based cement composite as a partial binder substitute. Selected secondary raw materials were pre–treated by grinding to a specific surface of 300 and 500 mkg. As a reference material, a commercially available mixture was selected to produce cement composites intended for the environment with high physical–mechanical demands. Cement was substituted by secondary raw materials at a rate of 20 and 40% in the reference recipe. Basic physical–mechanical characteristics such as compressive strength and tensile strength at bending were determined on standard 160×40×40 mm prisms. Strengths were determined after 3 and 28 days of ageing. In addition, the influence of binder substitute by the admixtures on the microstructure of cement stone was monitored by sample scanning using an RTG tomography. The positive effect of a part of the binder substitution by selected secondary raw materials on microstructure was proved in all tested samples. From the measured data, it is evident that the higher specific surface of the pre–treated admixtures did not have a significant positive effect either on strengths or the microstructure.
Raw materials for mullite grog manufacturing
(IOP Publishing, 2018-07-07) Nevřivová, Lenka
The primary condition for manufacturing is the correct choice of raw material, a suitable treatment facility, and a kiln capable of firing at temperatures above 1400 °C. This paper assesses some local raw materials for grog manufacturing and compares the results with a mullite grog of similar properties that is available on the European market.
Mortars with crystalline additive in aggressive environments
(IOP Publishing, 2018-07-16) Žižková, Nikol; Nevřivová, Lenka; Lédl, Matěj; Keprdová, Šárka
The paper describes how a crystalline additive influences the properties of cementbased composites. The investigation was focused on the degradation of mortars with crystalline additive exposed to selected aggressive environments. The specimens were tested for compressive and flexural strength. The influence on the microstructure is also discussed (high pressure mercury intrusion porosimetry, SEM, DTA). The results confirmed the positive influence of a crystalline additive on the values of compressive strength after exposure to all aggressive environments.

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