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Aqueous CO2 Sequestration for Low-Carbon Ready-Mix Concrete
Chong, Yujie, Jamie ; Chua, Guan Feng ; Zhao, Mingshan ; Yip, Colin ; Daneti, Saradhi Babu ; Jin, Fei
The cement industry accounts for 8% of global energy- and process-related greenhouse gas emissions. To achieve global net-zero emission targets by 2050, the need for commercially ready low-carbon construction materials is becoming increasingly urgent. The fixation of captured carbon dioxide in concrete through CO₂ sequestration is a crucial area of study to reduce concrete embodied carbon. This paper discusses the development of a low-carbon ready-mix concrete (RMC) with aqueous CO2 sequestration, and the synergy between carbon dioxide and other constituent materials. The effectiveness of this approach was evaluated through mineralogical composition analysis using TGA, and the mechanical and rheological properties of various concrete mixes were studied. Aqueous CO2 sequestration using carbonated mixing water can stably fix up to 0.84% of CO2 by weight of cement within the cement matrix as CaCO3. The poor workability and incompatibility with GGBS that results from this approach were addressed by the inclusion of RCA as an external source of alkalinity and lubrication. This mix of low-carbon RMC has similar strength and rheological properties to conventional RMC and achieved an embodied carbon reduction of approximately 47%.
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Suitability of vitrified lignite bottom ash for composite cements.
Bayer, Petr ; Krátký, Josef (oponent) ; Wolter, Albrecht (vedoucí práce)
The present master’s thesis seeks to develop a better understanding of using vitrified lignite bottom ash as a clinker substitute in composite cements. The influence of added vitrified bottom ash, as well as its fineness, alkaline solutions and its concentration was investigated. In composite cements prepared as specified in DIN EN 197 - 1, the clinker was replaced by 30 % of the vitrified bottom ash. In particular, the composite cements with vitrified bottom ash of fineness 5549 cm2/g and 8397 cm2/g were prepared. Furthermore, in order to stimulate the pozzolanic and/or geopolymeric reaction of the vitrified bottom ash, alkaline solutions of hydroxides and sulphates in two different concentrations were added. Mechanical properties of the prepared samples were characterized by mechanical strength testing on prisms with a proportion of 40×40×160 mm as specified in DIN EN 196 - 1. The non-destructive measurement of dynamic E-modulus and destructive testing on compressive and flexural strength were conducted. Moreover, particle size distribution and chemical analysis of input materials were performed by means of laser granulometry and X ray fluorescence, respectively. The hardened composites were investigated on phase composition and microstructure using X-ray diffraction and scanning electron microscopy after 2 and 28 days of hydration. Finally, the results showed that the mechanical properties are independent on the added amount of alkaline concentration or fineness of grounded bottom ash. However, the noticeable lower mechanical strengths were observed for samples with hydroxides activation likely due to the early silicate hydrogel formation. The strengths for samples with sulphate activation did not reach the strength of the reference mortar.
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Vývoj hmot pro 3D tisk prvků splňujících požadavky dopravních staveb
Romanová, Dorota ; Melichar, Jindřich (oponent) ; Žižková, Nikol (vedoucí práce)
Táto bakalárska práca sa zaoberá využitím druhotných surovín ako čiastočnej náhrady portlandského cementu v cementových kompozitoch so zameraním na požiadavky dopravných stavieb. Teoretická časť pozostáva z opisu vstupných surovín ako aj náhrad cementu, sledovaných vlastností 3D tlačených zmesí a popisu charakteristík technológie. Praktická časť je zameraná na experimentálne overenie vybraných vlastností so sledovaním vplyvu dávky polymérnej a bio-polymérnej prísady v navrhnutých receptúrach a následné vyhodnotenie najvhodnejšej z nich pre 3D tlač.
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Využití kalcinovaných jílů pro polymery modifikované malty
Macíková, Barbora ; Sokola, Lubomír (oponent) ; Žižková, Nikol (vedoucí práce)
Tato práce se zabývá použitím metakaolinu jako částečné náhrady cementu pro polymery modifikované malty. Teoretická část popisuje negativní dopad výroby cementu na životní prostředí. Pozornost je věnována použití doplňkových cementových materiálů ve snaze snížit uhlíkovou stopu, kdy je za hlavní alternativu považován metakaolin. Zkoumá se jeho složení, dostupnost, využití, vlastnosti a vhodnost použití pro polymery modifikované malty. Praktická část je zaměřena na ověření příslušných vlastností malt s metakaolinem jako pojivovou složkou a jeho vhodnost pro budoucí využití jako doplňkového cementového materiálu.
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Suitability of vitrified lignite bottom ash for composite cements.
Bayer, Petr ; Krátký, Josef (oponent) ; Wolter, Albrecht (vedoucí práce)
The present master’s thesis seeks to develop a better understanding of using vitrified lignite bottom ash as a clinker substitute in composite cements. The influence of added vitrified bottom ash, as well as its fineness, alkaline solutions and its concentration was investigated. In composite cements prepared as specified in DIN EN 197 - 1, the clinker was replaced by 30 % of the vitrified bottom ash. In particular, the composite cements with vitrified bottom ash of fineness 5549 cm2/g and 8397 cm2/g were prepared. Furthermore, in order to stimulate the pozzolanic and/or geopolymeric reaction of the vitrified bottom ash, alkaline solutions of hydroxides and sulphates in two different concentrations were added. Mechanical properties of the prepared samples were characterized by mechanical strength testing on prisms with a proportion of 40×40×160 mm as specified in DIN EN 196 - 1. The non-destructive measurement of dynamic E-modulus and destructive testing on compressive and flexural strength were conducted. Moreover, particle size distribution and chemical analysis of input materials were performed by means of laser granulometry and X ray fluorescence, respectively. The hardened composites were investigated on phase composition and microstructure using X-ray diffraction and scanning electron microscopy after 2 and 28 days of hydration. Finally, the results showed that the mechanical properties are independent on the added amount of alkaline concentration or fineness of grounded bottom ash. However, the noticeable lower mechanical strengths were observed for samples with hydroxides activation likely due to the early silicate hydrogel formation. The strengths for samples with sulphate activation did not reach the strength of the reference mortar.
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