Karakterizacija in imobilizacija bele žlindre iz procesov sekundarne metalurgije v cementnih kompozitih

Zalar Serjun, Vesna (avtor), Mirtič, Breda (mentor), Mladenovič, Ana (komentor), Vukelič, Željko (član komisije za zagovor), Dolenec, Matej (član komisije za zagovor), Milačič, Radmila (član komisije za zagovor), Bokan-Bosiljkov, Violeta (član komisije za zagovor)

Osnovno izhodišče dela je definirati tak cementni kompozit z dodatkom bele (ponovčne) žlindre, ki bo zagotavljal funkcionalnost za izbrane namene ter hkrati preprečeval širjenje škodljivih snovi v okolje. Ponovna uporaba (recikliranje) sekundarnih metalurških žlinder iz proizvodnje nerjavnega jekla ima namreč pomemben sinergijski učinek na okolje. V okviru preiskav smo se osredotočili na podrobno karakterizacijo žlindre, ki izhaja iz dveh različnih procesov sekundarne rafinacije visoko legiranega jekla v ponovci ter na cementne kompozite z dodatkom le-te. V sklopu laboratorijskih raziskav je bilo preiskanih več cementnih kompozitov z dodatkom bele ponovčne žlindre. Vzporedno so bili za primerjavo preiskani tudi referenčni cementni kompoziti in kompoziti z dodatkom konvencionalnega suplementarnega cementnega materiala (apnenčeva moka). Rezultati kažejo, da dobrih 50 mas. % preiskovane žlindre sestavljajo hidravlično aktivni minerali, med katerimi močno prevladujejo kalcijevi aluminati. Malte z dodatkom preiskovane žlindre izkazujejo večjo stopnjo prirastka trdnosti v primerjavi z maltami z dodatkom apnenčeve moke, kar je posledica večje količine nastalih hidratacijskih produktov. Dodajanje preiskovane žlindre cementnim kompozitom je bilo ocenjeno tudi iz vidika okoljskih vplivov na podlagi dolgoročnega izlužitvenega testa. Preiskovana žlindra stabilizira krom z njenimi redukcijskimi in hidravličnimi karakteristikami, kar kaže na pomemben pozitiven učinek preiskovane žlindre v cementnem kompozitu. V okviru mehanskih preiskav malt po izlužitvenem testu je bila ovrednotena trajnost, ki kaže na to, da preiskovana žlindra ne zmanjšuje trajnosti tovrstnih malt. Rezultati kažejo, da se preiskovana bela ponovčna žlindra lahko uporabi kot suplementarni cementni material.

• Jezik: Neznan jezik
• Ključne besede: bela žlindra, imobilizacija, cementni kompoziti, hidratacija, krom
• Vrsta gradiva: Doktorsko delo/naloga
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Leto izida: 2015
• PID: 20.500.12556/RUL-71855
• COBISS.SI-ID: 7105889
• Datum objave v RUL: 29.07.2015

Sekundarni jezik

• Jezik: Neznan jezik
• Naslov: Characterization and immobilization of white slag from secondary metallurgical processes in cementitious composites

Izvleček

The fundamental objective of this study was to define such a cement composite with the addition of white (ladle) slag, which will provide functionality for selected purposes and furthermore, prevent the leaching of toxic elements into the environment. The recovery (recycling) of secondary metallurgical slags from stainless steel production has an important synergistic impact on the environment. In this study, detailed characterization of slag derived from two different ladle refining processes of stainless steel production has been performed. In order to assess its potential for use as a supplementary cementitious material, slag cement composites as well as slag itself were investigated. A comparative study of reference cement composites and cement composites to which a conventional supplementary cementitious material (limestone filler) had been added, was also performed. The results showed that the slag contains hydraulic phases to a total amount of about 50 %. Calcium aluminates are the predominant constituents. In the case of slag cement composites, a larger degree of strength development was observed in comparison to the cement composite with the addition of limestone filler. This was attributed to the larger proportion of hydration products formed in the slag cement composite. The environmental impact of cement composite with the addition of the investigated slag was further evaluated. The results revealed that chromium was immobilized in the cement composites with the addition of slag. Cr(VI) content originating from the cement was also appreciably reduced by the added slag, which thus had significant positive environmental effects. The stabilization process is controlled by the reducing and hydraulic properties of the slag. It was demonstrated that the presence of the investigated slag in cement composites does not influence its durability. The investigated white (ladle) slag can be implemented in cement composites as supplementary cementitious material.

• Ključne besede: ladle slag, immobilization, cement composites, hydration, chromium