Vpliv TiO2 na nastanek in razvoj faz cementnega klinkerja : magistrsko delo

Primožič, Janja (author), Dolenec, Sabina (mentor), Vrabec, Mirijam (comentor)

Zaradi velikega ogljičnega odtisa pri proizvodnji običajnega portlandskega cementa se razvijajo nova veziva, s katerimi bi zmanjšali količine CO2 izpustov ob proizvodnji. Eden takih je sulfoaluminatno-belitni klinker, katerega glavne faze so kalcijev sulfoaluminat, belit in ferit. Namen magistrske naloge je proučiti, kako TiO2 vpliva na razvoj klinkerjevih faz sulfoaluminatno-belitnega klinkerja. V ta namen smo sintetizirali sulfoaluminatno-belitni cementni klinker z naslednjo želeno sestavo faz: 65 % kalcijevega sulfoaluminata, 25 % belita in 10 % ferita in pripravili cement. Cementnemu klinkerju smo dodali štiri različne deleže TiO2 (0,5; 1,0; 2,0 in 4,0 mas. %), ki smo jih sintetizirali pri štirih različnih temperaturah (1150 °C, 1200 °C, 1250 °C in 1300 °C). Sestavo faz klinkerja smo določili z rentgensko praškovno difrakcijsko analizo in Rietveldovo metodo. Na izbranih vzorcih cementnega klinkerja smo z vrstično elektronsko mikroskopijo z energijsko disperzijsko spektroskopijo opazovali mikrostrukturo klinkerja in kemijsko sestavo faz. Iz izbranih vzorcev smo pripravili cement, ki smo mu določili specifično površino s plinsko sorpcijo in porazdelitev velikosti delcev z lasersko granulometrijo. Proučevali smo njegovo reaktivnost z izotermno kalorimetrijo in določili tlačne trdnosti. Ugotovili smo, da so količine kalcijevega sulfoaluminata in belita v vseh vzorcih dokaj konstantne, ter da se količina ferita z naraščanjem koncentracije TiO2 v vzorcu zmanjšuje, količina perovskita pa povečuje. Količina manj zastopanih faz se z večanjem količine TiO2 v vzorcu povečuje, vendar se z naraščanjem temperature količine zmanjšujejo. Hidratacija najkasneje poteče pri vzorcu z največjim deležem TiO2, pri ostalih štirih vzorcih do hidratacije pride približno po istem času od začetka meritve. Tlačna trdnost je manjša v vzorcih z večjo količino TiO2, kar je najverjetneje posledica nastanka nereaktivnega perovskita.

• Language: Slovenian
• Keywords: TiO2, sulfoaluminatno-belitni klinker, klinkerjeve faze, reaktivnost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: J. Primožič
• Year: 2023
• Number of pages: XVIII, 79 f.
• PID: 20.500.12556/RUL-150801
• UDC: 55
• COBISS.SI-ID: 167927299
• Publication date in RUL: 23.09.2023

PRIMOŽIČ, Janja, 2023, Vpliv TiO2 na nastanek in razvoj faz cementnega klinkerja : magistrsko delo [online]. Master’s thesis. Ljubljana : J. Primožič. [Accessed 19 May 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=150801

Secondary language

• Language: English
• Title: Influence of TiO2 on cement clinker phase formation and development : master's thesis

Abstract

Due to the high carbon footprint associated with the production of ordinary Portland cement, new binders are being developed to reduce carbon dioxide emissions during production. One such binder is the sulfoaluminate-belite clinker, with its main phases being calcium sulfoaluminate, belite, and ferrite. The purpose of this master thesis is to investigate how TiO2 affects the development of the clinker phases in the sulfoaluminate- belite clinker. For this purpose, a sulfoaluminate- belite cement clinker with the following desired phase composition was synthesised and cement was prepared: 65 % calcium sulfoaluminate, 25 % belite, and 10 % ferrite. Four different TiO2 contents (0.5; 1.0; 2.0; and 4.0 wt. %) were added to the cement clinker, which was then fired at four different temperatures (1150 °C, 1200 °C, 1250 °C, and 1300 °C). The phase composition of the clinker was determined using X-ray powder diffraction analysis and Rietveld method. The microstructure of the cement clinker and the chemical composition of the phases were investigated using scanning electron microscopy with energy-dispersive spectroscopy on selected clinker samples. Cement was prepared from the selected samples on which the specific surface area was determined using gas sorption and the particle size distribution by laser granulometry. We studied its reactivity by isothermal calorimetry and the compressive strengths were determined. It was found that the amounts of calcium sulfoaluminate and belite were relatively constant in all samples, while the amount of ferrite decreased with increasing TiO2 concentration in the sample, while the amount of perovskite increased. The amount of less represented phases increases with increasing TiO2 content of the sample, while the amount decreases with increasing temperature. Hydration occurs at the latest in the sample with the highest TiO2 content, while in the other four samples, hydration occurs at about the same time from the beginning of the measurement. The compressive strength is lower in samples with a higher amount of TiO2, which is most likely the result of the formation of non-reactive perovskite.

• Keywords: TiO2, sulfoaluminate-belite clinker, clinker phases, reactivity