DEF of high-performance concrete with rapid, non-standard heat-treatment

  • High-performance concrete is often heat-treated to increase early \(\underline {strength}\). Standardized temperature conditions for at least 24 h and sulphate-resistant cement thereby preventing (\underline {delayed ettringite formation}\) (DEF). In contrast, this paper investigates the risk of DEF for rapidly heat-treated HPC with a minimum temperature duration of 1 h to achieve a rapid early strength for stripping. In addition, a binder is used that does not exhibit increased (\underline {sulphate resistance}\). For this purpose, standard prisms (L x W x H = 16 × 4× 4 [cm]) are heat-treated at 80 °C between 1 and 6 h without a pre-storage time. Samples with a temperature duration of 24 h serve as reference. First, the (\underline {pore structure}\) is analyzed using Mercury (\underline {porosimetry}\) to identify damage to the (\underline {concrete matrix}\) due to the rapid heat treatment. The investigation of DEF is achieved by two common approaches. The sulphate resistance is determined by means of wet-dry cycles on specimens for 90 days, whereby the changes in mass and strain as well as the cracking pattern on the concrete surface serves as a qualitative evaluation criterion. In addition, the SVA method on specimens directly after heat treatment, which determines the change in (\underline {mechanical properties}\) and the (\underline {swelling behaviour}\) of the concrete, leads to a quantitative evaluation of sulfate resistance. The measured pore distribution of the samples shows a significant increase of the capillary pores of up to 109% for decreasing temperature durations. However, the porosity does not affect the sulphate resistance of the concrete. The wet-dry cycles cause no damage due to DEF, since the change in mass and strains decreases with increasing cycles from up to 62.7% to − 2.5%. Furthermore, no visual differences were detected on the concrete surface between specimens with and without (\underline {sulphate attack}\). As a result of the SVA test, maximum absolute strains of about 0.1 mm/m occur that are below the limit value of 0.152 mm/m. Also, the mechanical properties do not show a reduction in strength, but even an increase in tensile strength. In conclusion, the high-performance concrete formulation used in combination with rapid heat treatment investigated here did not result in detectable damage due to DEF.

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Author:Jan StindtORCiDGND, Luca-Alexander KempfORCiDGND, Patrick FormanORCiDGND, Rolf BreitenbücherGND, Peter MarkORCiDGND
Parent Title (English):Case studies in construction materials
Place of publication:Amsterdam
Document Type:Article
Date of Publication (online):2024/02/26
Date of first Publication:2023/07/07
Publishing Institution:Ruhr-Universität Bochum, Universitätsbibliothek
Tag:Open Access Fonds
Delayed ettringite formation; High-performance concrete; Porosimetry; Rapid heat treatment; SVA; Wet-dry cycles
Issue:Article e02289
First Page:e02289-1
Last Page:e02289-12
Article Processing Charge funded by the Deutsche Forschungsgemeinschaft (DFG) and the Open Access Publication Fund of Ruhr-Universität Bochum.
Institutes/Facilities:Lehrstuhl für Massivbau
Dewey Decimal Classification:Technik, Medizin, angewandte Wissenschaften / Ingenieurbau, Umwelttechnik
open_access (DINI-Set):open_access
faculties:Fakultät für Bau- und Umweltingenieurwissenschaften
Licence (English):License LogoCreative Commons - CC BY-NC-ND 4.0 - Attribution-NonCommercial-NoDerivatives 4.0 International