Effect of Slag Reactivity Influenced by Alumina Content on Hydration of Composite Cements

Kucharczyk, Sylwia; Deja, Jan; Zając, Maciej

doi:10.3151/jact.14.535

Cited by 22 publications

(8 citation statements)

References 43 publications

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“…Already at one day, the reaction degree of 60~70% is achieved. This in turn demonstrates that the reaction of the investigated material is rapid when compared to typical SCMs like slag and fly ash 33,44,45 and similar to the hydration kinetics of metakaolin 46-48 . Re-carbonated paste as cement constituent. The impact of the carbonated paste on the hydrates assemblage in a composite cement comprising cement clinker, the carbonated paste and 5% of anhydrate was predicted by the thermodynamic model as well.…”

Section: Results and Interpretationsupporting

confidence: 59%

“…The calcite content does not change significantly as also predicted by the thermodynamic modeling. The shape of effects in the range of 50-150 °C on the DTG curves indicates that ettringite is not present or its content is low 33,44 . This is confirmed by the XRD data shown in Fig.…”

Section: Results and Interpretationmentioning

confidence: 99%

“…it does not include the water bound in portlandite 32 [p. 3]. The bound water content is significantly lower when compared to a hydrating cement that is in the range of 20 g/100 g dry cement , thought, it is well in the range for similar pozzolanic systems 33,44,45 . The portlandite content is decreasing in parallel to the increasing bound water content.…”

Section: Results and Interpretationmentioning

confidence: 99%

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Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Skoček

Zając

Haha

2020

Sci Rep

Self Cite

128

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Reduction of co 2 emissions associated with cement production is challenging in view of the increasing cement demand and the fact that major part of the emissions originates from the main raw material used -limestone -which can be only to extremely low amount substituted. A carbon capture and Utilization (CCU) approach based on mineralization of fines derived from concrete appears to be a viable alternative to reduce these emissions. the co 2 sequestration and the reactivity of the obtained carbonated recycled fines is experimentally demonstrated for lab as well as industrial materials for different mineralization conditions. It is shown that all CO 2 originally released by limestone calcination during clinker production can be sequestered by the full carbonation of the fines within a short time. Upon full carbonation, gels with pozzolanic properties form in the fines irrespective of the conditions tested. The carbonated fines have specific CO 2 savings more than 30% higher than the simple clinker replacement by limestone.Global urbanization and economic development increase demand for new buildings and infrastructure and hence for concrete. Already now, concrete is the second most used substance by mass after water. Even though concrete has low specific CO 2 emissions below 150 kg CO2,eq /ton concrete 1 , its abundance makes it responsible for 5-8% of man-made CO 2 emissions 1-4 . Most of the concrete's emissions result from production of the main cement component, the clinker. Hence, focus of researchers as well as of cement producers has been on lowering the clinker content in cements and on improving the efficiency of clinker production. As summarized in 1 , both these approaches have already reached their potentials in mature economics. Almost all suitable Supplementary Cementitious Materials (SCMs) available are already used in cement and concrete production. For the clinker production, further energy efficiency improvements would have only a minor effect as the energy consumption approaches the lowest theoretical value and is often driven by additional objectives such as alternative fuels usage rate.Nevertheless, the cement industry needs to drastically reduce its emissions and at the same time satisfy the increasing cement demand of the global economy 5 . At the level of concrete structures and concrete applications, several approaches can bring considerable CO 2 savings. These include re-usable structures with extended service life or concretes with reduced cement contents 3,6 . At the level of cement production, extended use of calcined clays and limestone as SCM are the only approaches applicable at large enough scale. With the ongoing departure from coal-fired power plants and decreasing demand for pig iron in mature markets, the availability of blast furnace slags and fly ashes is expected to decrease. Calcined clays and limestone have the potential to replace these SCMs in the current market as well as provide sufficient volumes of SCMs in growing markets. However, clinker replacement by limestone o...

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Section: Results and Interpretationsupporting

confidence: 59%

Section: Results and Interpretationmentioning

confidence: 99%

Section: Results and Interpretationmentioning

confidence: 99%

See 1 more Smart Citation

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Skoček

Zając

Haha

2020

Sci Rep

Self Cite

128

View full text Add to dashboard Cite

show abstract

“…-limestone ternary systems, this synergetic effect is limited as the slag contains less aluminum but more magnesium than fly ash or metakaolin. In these systems a significant part of the alumina is bound in hydrotalcite and C-S-H phase [91,93,94] limiting the amount of AFm phases and thus the interaction of limestone with slag. However, for slags characterized by high alumina content a similar synergetic effect an important role.…”

Section: Hydrate Assemblagementioning

confidence: 99%

“…The modelling of the hydration process as a function of time can be used to indirectly assess the hydration of amorphous materials such as fly ash [112,136], synthetic glasses [93,137] and metakaolin [138] in cementitious matrixes, by calculating the consumption of portlandite due to their reaction and compare it to the measured portlandite contents. The reaction of SCMs can also be assessed indirectly by comparing the measured increase of the bound water content or chemical shrinkage [112,136] with thermodynamic modelling or mass balance calculations.…”

Section: Changes In Solid Phases During Hydrationmentioning

confidence: 99%