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Valorization of a steel industrial co-product for the development of alkali-activated materials : effect of curing environments

Sarri Arezki, Oualit Mehena, Kennouche Salim

Advances in Materials Science

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2023

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Vol. 23, nr 2(76)

45--63

EN

While natural resources are becoming scarce and climate change is accelerating, the recovery and recycling of wastes and by-products is an effective way to deal with the economic and ecological constraints of recent decades. The valorization of industrial by-products in civil engineering is a common practice either by their incorporation during the manufacture of Portland cements or as a partial replacement of cement during the production of concrete. The present work aims to develop waste-based alkali-activated materials WAAMs intended for civil engineering applications as a potential alternative to cement-based materials. A steel industrial by-product called commonly granulated blast furnace slag GBFS was used alone as a solid CaO-rich precursor; two alkaline activators such us sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) were used separately for the production of two-part alkali-activated materials. Besides the microstructure analysis of the hardened samples, the influence of activator/precursor mass ratio, NaOH molarity, and two curing environments (Room temperature and 60°C) on the compressive strength, water accessible porosity, mass loss, and drying shrinkage were assessed. The results showed that a high Liquid/Solid ratio leads to a decrease in the compressive strength of the samples, while high NaOH molarity significantly improves the mechanical properties by reducing the porosity of the specimens. Moreover, alkaline silicate activator provides higher compressive strengths compared to the alkaline hydroxide activator, especially when the samples were cured at room temperature where a maximum 28days-compressive strength value of 105.28 MPa was achieved. For the samples activated using sodium hydroxide solution, the results revealed that their curing at 60°C promotes obtaining high initial-compressive strengths (7 days) before decreasing subsequently as a function of the curing time. As an indication, at high alkaline concentration (NaOH = 9M), a mechanical strength decline of 21% was recorded between a curing time of 7 to 28 days. Moreover, curing at 60°C induced high porosity, significant mass loss and high drying shrinkage. SEM analysis highlighted a dense, homogeneous microstructure without apparent defects, in particular for the samples where the alkali silicate activator was used.

2

A study of the influence of selected transition metals on the solid state Reactivity in a Fe-KClO4 mixture

Czajka B., Foltynowicz Z., Wachowski L.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 2

271--283

EN

The effect of selected transition metal powders (Zn, Ti, Mo and nano-Fe), in the concentration range from 0-5 wt.%, when used as activators in the highly calorific mixture Fe-KClO4 (containing 16 wt.% KClO4), has been studied. It has been established that zinc and molybdenum powders can act as factors in decreasing the activation temperature and increasing the effectiveness of the oxidant used. Titanium powder increases the oxygen conversion rate and the amount of energy released. Iron nano-powder has only a slight influence on the above mentioned parameters.

3

Dodatki do probówek w medycznych laboratoriach diagnostycznych

Bergmann K.

Laboratorium - Przegląd Ogólnopolski

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2013

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nr 7-8

24--27

PL

Prawidłowy dobór oraz pobranie materiału biologicznego mają kluczowe znaczenie dla właściwego wykonania badania laboratoryjnego oraz otrzymania wiarygodnego wyniku. W pracy opisano powszechnie stosowane dodatki do probówek do pobierania krwi - antykoagulanty, aktywatory/inhibitory oraz dodatki separujące.

EN

Proper selection and collection of biological material is crucial for the performance of laboratory test and to obtain reliable results. This paper describes commonly used additives to blood collection tubes - anticoagulants, activators/inhibitors and separating substances.

4

Otrzymywanie cynkowego aktywatora wulkanizacji siarkowej

Stechman M.

Chemik

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2007

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Vol. 60, nr 10

475-478

PL

Przedstawiono główne składniki mieszanek gumowych pozwalające na uzyskanie wyrobów o projektowanych właściwościach, metodą wulkanizacji siarkowej. Omówiono zarówno rolę wypełniaczy jak i aktywatorów wulkanizacji siarkowej, ze szczególnym uwypukleniem tlenku cynku i glinokrzemianów warstwowych. Przedstawiono wyniki badań nad otrzymywaniem nowoczesnego aktywatora wulkanizacji siarkowej – nanotlenku cynku na nośniku mineralnym.

EN

Main ingredients of rubber compounds, that enable preparation of special products in sulphur vulcanization method, were described. The role of fillers and sulphur vulcanization activators was discussed, particularly zinc oxide and layered aluminosilicates. Results of research on modern sulphur vulcanization activators preparation – zinc nanooxide – were presented.

5

Activator - Induced Modification of Selected Properties of Heat Generating Fe-KClO4 Mixture

Wachowski L., Czajka B.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 1-2

51-63

EN

The effect of the kind (Zn, Mo, or Ti) and amount (the concentration range 0-5 wt.%) of the metallic powder used as an activator introduced into the highly calorific mixture of Fe and KClO4 has been studied. In all samples studied, with increasing amount of the activator introduced into the system Fe-KClO4 the energy effect has been found to increase in the following sequence Ti

6

Effect of activators on structure of 'Turow' brown coal and its behaviour at the pyrolysis.

Shevkoplyas V.

Prace Naukowe Instytutu Chemii i Technologii Nafty i Węgla Politechniki Wrocławskiej. Konferencje

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1999

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Vol. 9, nr 56

319-324

EN

The effect of activators having alkaline and acid properties upon the structural organization of 'Turow' brown coal and its behaviour at pyrolysis has been studied by methods of X-ray diffraction and IR-spectroscopy. It has been demonstrated that on the stage of coal impregnation (preparing) to pyrolysis the KOH or HCL addition to coal disordes considerably the intial coal structure and changes parameters Lc, La, h/l002. In the same time with a carbon skeleton intial coal. The KOH addition increases the adsorption bands intensity at 2920, 1500, 1450-1380 cm-1 and 1270-1220cm-1 whereas HCL addition decrease the intensity of adsorption bands at 1610, 1450-1380 cm-1 and 1200-1100 cm-1 that suggests a different mechanism of activators effect pon coal. It has been shown that the KOH or HCL addition is activating the brown coal pyrolysis and coal organic mass (COM) conversion is incrased in 1,5-2,0 times. The interrelation between a degree of interlayer ordering of cristallite (h/l002) and the yield of pyrolysis liquid products (500C) from the initial coal and having a KOH or HCL addition has been detected. The structure of carbonized solid residues (CSR) of pyrolysis within temperature region of 400-700C has been studied. It has been demonstrated that the coal is passing through several stages of structural reorganisation in the course of pyrolysis. The most reorganisation of the cristallite package is taking place within temperature region 400-500C.

PL

Metodą strukturalnej analizy rentgenowskiej oraz spektroskopii w podczerwieni stwierdzono, że wstępne przygotowanie do aktywacji węgla z koplalni 'Turow' przy użyciu KOH i HCL prowadzi do reorganizacji pierwotnej struktury węgla brunatnego. Reorganizacja struktury jest możliwa w wyniku hydrilizy spolaryzowanych wiązań C-O-C i C-C, rozerwania wiązań wodorowych (KOH) i związków organo-mineralnych oraz usunięcia połączeń tworzących kompleksy kationowe (HCL). Stwierdzono, że istnieje związek pomiędzy wartościami parametru h/l002 oraz ilością ciekłych produktów pirolizy w temperaturze 500C. Aktywacja węgla za pomocą KOH zwiększa ilość ciekłych produktów do 33,0% ogólnej konwersji organicznej masy węgla. Pokazano, że zmiana reorganizacji struktury węgla podczas pirolizy przebiega etapami. Ustalono, że istnieje zależność pomiędzy zmianami wartości parametru h/l002, stosunkiem Lc/La w pakiecie krystalitu a ukierunkowaniem reakcji w procesie pirolizy.