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Partial replacement of OPC with CSA cements – effects on hydration, fresh-, hardened-properties
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.ORCID iD: 0000-0001-5136-9412
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.ORCID iD: 0000-0002-6797-9300
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Skanska Teknik AB, Skanska Sverige AB, 40518 Göteborg, Sweden.
BESAB AB, Technical Manager, Berg & Betong, Tagenevägen 7, 42259 Hisings Backa, Göteborg, Sweden.
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2023 (English)In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 35, no 5, p. 207-224Article in journal (Refereed) Published
Abstract [en]

The effects of a partial replacement of Ordinary Portland cement (OPC) with three types of calcium sulfoaluminate (CSA) cements (40 wt% and 20 wt%) were investigated. The obtained results were generally in agreement with previously published data but with few interesting exceptions. Setting times were shortened due to the formation of ettringite. The maximum hydration temperature increased for concretes containing 40 wt% of CSA but decreased when 20 wt% replacement was used. The decrease was related to the deficiency of the available sulfates, which limited the formation of ettringite. The presence of extra anhydrite and calcium oxide was associated to the delayed establishment of the second temperature peak in contrast to OPC-based concretes. Their surplus delayed calcium aluminate and belite reactions, and triggered renewed formation of ettringite, C-S-H and portlandite. Effects of aluminum hydroxide were also indicated as possibly important, although not proved experimentally in this research. The slightly lower compressive strength measured for mixes containing 40 wt% of CSA were linked with more formed ettringite. The same factor was indicated as the key to the reduction of the total shrinkage in mixes containing 40 wt% of CSA and increased for the lower CSA replacement level. In that case, the insufficient amount of formed ettringite caused too small expansion, which could not efficiently mitigate or compensate the developed shrinkage.

Place, publisher, year, edition, pages
ICE Publishing , 2023. Vol. 35, no 5, p. 207-224
Keywords [en]
Calcium sulfoaluminate cement (CSA), Hydration, Microstructure-SEM-EDS, Ordinary Portland cement (OPC), Shrinkage, XRD
National Category
Other Materials Engineering
Research subject
Building Materials
Identifiers
URN: urn:nbn:se:ltu:diva-93760DOI: 10.1680/jadcr.22.00054ISI: 000880071500001Scopus ID: 2-s2.0-85140233648OAI: oai:DiVA.org:ltu-93760DiVA, id: diva2:1707600
Funder
Svenska Byggbranschens Utvecklingsfond (SBUF)Rock Engineering Research Foundation (BeFo)
Note

Validerad;2023;Nivå 2;2023-06-29 (joosat);

Available from: 2022-11-01 Created: 2022-11-01 Last updated: 2024-04-16Bibliographically approved
In thesis
1. Low Portland cement content concretes at freezing and subfreezing temperatures
Open this publication in new window or tab >>Low Portland cement content concretes at freezing and subfreezing temperatures
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Concrete is the most used building material. With the increasing growth of industries and urbanization globally; the demand for concrete is increasing significantly. Ordinary Portland Cement (PC) is the binder used to produce typical concrete. Unfortunately, for every ton of manufactured cement about 0.61-ton CO2 is emitted into the earth’s atmosphere. As a result, several solutions have been implemented to reduce the usage of this material in the production of concrete. This includes its partial or full replacement with supplementary cementitious materials (SCMs) or alternative binders. Some of these combinations could be problematic to be used in cold climates due to a lower developed hydration heat, slower setting, or worse frost durability.

In winter the immediate exposure of fresh concrete to freezing temperatures results in pore ice formation and could delay or completely stop the hydration process. This is commonly prevented by using an additional heating system installed in concrete or the formwork. Unfortunately, usually, it adds complexity, increases the price, and depending on the used power source, could increase the CO2 footprint. Another potentially simpler and more sustainable solution is to modify the concrete itself by adjusting the mix design, by using certain chemical admixtures and special cementitious binders.

This research aimed to better understand how partial replacement of Portland cement with GGBFS and/or CSA cement affects the properties of concretes exposed to freezing and subfreezing temperatures in a fresh state and at a young age. The secondary aim was to evaluate a possible application of UHPC to protect new and existing concrete structures from frost damage.

The research included a literature review of methods used to produce concrete structures at zero and subzero temperatures. A special emphasis was on the application of chemical and mineral admixtures that could eliminate the need to use heat treatments. The output of this analysis enabled to narrow the scope of the research.

The experimental program focused on the optimization, testing, and analysis of mixes containing various combinations of chemical admixtures, CSA cement, and Portland cement. Tests included exposure to freezing and subfreezing temperatures. The aim was to lower the freezing point of water and promote faster hydration and strength gain. Fresh and hardened properties were determined for all produced concretes. The phase transition of pore water into ice, the ice-forming temperature, and their effects on the binder matrix were studied using differential scanning calorimetry (DSC). Other tests included ultrasonic pulse velocity measurements (UPV), bond test (pull-off), scanning electron microscope (SEM) for analysis of the microstructure and phase composition, frost durability evaluation with Båras test, semi-adiabatic calorimetry to study hydration processes, compressive strength measurements.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2024
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Building Technologies Composite Science and Engineering
Research subject
Building Materials
Identifiers
urn:nbn:se:ltu:diva-105133 (URN)978-91-8048-540-1 (ISBN)978-91-8048-541-8 (ISBN)
Public defence
2024-06-18, F1031, Luleå University of Technology, Luleå, 10:00 (English)
Opponent
Supervisors
Funder
InterregVinnovaSvenska Byggbranschens Utvecklingsfond (SBUF)Swedish Transport AdministrationSwedish Energy Agency
Available from: 2024-04-17 Created: 2024-04-16 Last updated: 2024-05-28Bibliographically approved

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Kothari, AnkitTole, IldaHedlund, HansCwirzen, Andrzej

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