TY - JOUR

T1 - Dunkelverfärbungen im unteren Wandbereich von Sichtbetonflächen

T2 - Wechselwirkungen zwischen Schalungsvibrationen und Betontechnologie

AU - Deiters, Macielle

AU - Schack, Tobias

AU - Fischer, Matthias

AU - Kiltz, Denis

AU - Haist, Michael

N1 - Publisher Copyright: , Ernst und Sohn. All rights reserved.

PY - 2024/9/20

Y1 - 2024/9/20

N2 - Dark discoloration in the lower wall area on exposed concrete surfaces – Interactions between formwork vibrations and concrete technology. The use of exposed concrete construction represents an irreplaceable architectural design element, particularly for the creation of represented concrete buildings. Despite an increasing variety of design possibilities, such as with colored or textured elements, many planners and builders still prefer smooth and uniformly light-colored exposed concrete surfaces created for using in-situ concrete constructions. Despite significant and technical advancements, optical irregularities like dark discolorations, are repeatedly observed in the production of such exposed concrete components. These discolorations cannot be fully explained by existing scientific approaches and cannot be technically eliminated so far. As a part of a research project jointly conducted by the Institute of Building Material Science of Leibniz University of Hannover and the German Concrete and Construction Technology Association (Deutscher Beton- und Bautechnik-Verein E. V.), the mechanisms leading to dark discolorations in lower wall areas of exposed concrete components were systematically investigated. In Particular, a direct influence of formwork vibrations in interaction with concrete technological properties was identified as a central factor for dark discolorations. The likelihood of such discolorations significantly increases when stiffening concrete (i. e. concrete whose age is approaching the initial setting time) are either directly or indirectly set into vibration by the formwork. A significant interaction was found between the timing of vibration initiation, the concrete technological properties and the vibration parameters (frequency and amplitude).

AB - Dark discoloration in the lower wall area on exposed concrete surfaces – Interactions between formwork vibrations and concrete technology. The use of exposed concrete construction represents an irreplaceable architectural design element, particularly for the creation of represented concrete buildings. Despite an increasing variety of design possibilities, such as with colored or textured elements, many planners and builders still prefer smooth and uniformly light-colored exposed concrete surfaces created for using in-situ concrete constructions. Despite significant and technical advancements, optical irregularities like dark discolorations, are repeatedly observed in the production of such exposed concrete components. These discolorations cannot be fully explained by existing scientific approaches and cannot be technically eliminated so far. As a part of a research project jointly conducted by the Institute of Building Material Science of Leibniz University of Hannover and the German Concrete and Construction Technology Association (Deutscher Beton- und Bautechnik-Verein E. V.), the mechanisms leading to dark discolorations in lower wall areas of exposed concrete components were systematically investigated. In Particular, a direct influence of formwork vibrations in interaction with concrete technological properties was identified as a central factor for dark discolorations. The likelihood of such discolorations significantly increases when stiffening concrete (i. e. concrete whose age is approaching the initial setting time) are either directly or indirectly set into vibration by the formwork. A significant interaction was found between the timing of vibration initiation, the concrete technological properties and the vibration parameters (frequency and amplitude).

KW - compaction

KW - concrete technology

KW - dark discoloration

KW - exposed concrete

KW - vibration of formwork

UR - http://www.scopus.com/inward/record.url?scp=85204395020&partnerID=8YFLogxK

U2 - 10.1002/best.202400059

DO - 10.1002/best.202400059

M3 - Artikel

AN - SCOPUS:85204395020

JO - Beton- und Stahlbetonbau

JF - Beton- und Stahlbetonbau

SN - 0005-9900

ER -