TY - JOUR

T1 - The Influence of Bleeding of Cement Suspensions on Their Rheological Properties

AU - von Bronk, Tabea

AU - Haist, Michael

AU - Lohaus, Ludger

N1 - Funding information: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG)—Projektnummer 411375374; funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Projektnummer 411375374 in the framework of SPP 2005 priority program ‘Opus Fluidum Futurum—Rheology of reactive, multiscale, multiphase construction materials’. Gef?rdert durch die Deutsche Forschungsgemeinschaft (DFG)-Projektnummer 411375374; funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-Projektnummer 411375374 in the framework of SPP 2005 priority program 'Opus Fluidum Futurum-Rheology of reactive, multiscale, multiphase construction materials'. The authors would like to thank HeidelbergerCement AG for providing the cement in the DFG SPP 2005 priority program.

PY - 2020/4/1

Y1 - 2020/4/1

N2 - Flowable concretes tend to segregate. The risk of segregation is particularly high when the concrete is vibrated during the compaction process. A well-known segregation phenomenon is the so-called "bleeding". This is a rise of water to the surface of the freshly poured concrete due to the difference in density between the mixing water and the concrete's denser solid components (aggregates, cement and additives). This type of segregation occurs particularly within the paste. The focus of this paper is, therefore, on the sedimentation behavior at the microscale of concrete and especially on the influence of this process on rheological properties of the cement paste. In addition to common bleeding tests of cement suspensions using standing cylinders, rheometric measurements were performed on the suspensions during the bleeding process. A measuring procedure was developed for the rheometric measurements of the sedimenting cement suspensions. The rheological properties of the investigated cement suspensions were determined at four specific measuring times and at four specific measuring heights (i.e., positions) each. With this method it could be shown that the cement suspensions are not homogeneous over their height and that bleeding has a great influence on the rheological properties of cement suspension.

AB - Flowable concretes tend to segregate. The risk of segregation is particularly high when the concrete is vibrated during the compaction process. A well-known segregation phenomenon is the so-called "bleeding". This is a rise of water to the surface of the freshly poured concrete due to the difference in density between the mixing water and the concrete's denser solid components (aggregates, cement and additives). This type of segregation occurs particularly within the paste. The focus of this paper is, therefore, on the sedimentation behavior at the microscale of concrete and especially on the influence of this process on rheological properties of the cement paste. In addition to common bleeding tests of cement suspensions using standing cylinders, rheometric measurements were performed on the suspensions during the bleeding process. A measuring procedure was developed for the rheometric measurements of the sedimenting cement suspensions. The rheological properties of the investigated cement suspensions were determined at four specific measuring times and at four specific measuring heights (i.e., positions) each. With this method it could be shown that the cement suspensions are not homogeneous over their height and that bleeding has a great influence on the rheological properties of cement suspension.

KW - Bleeding

KW - Cement suspension

KW - Rheology

UR - http://www.scopus.com/inward/record.url?scp=85082994734&partnerID=8YFLogxK

U2 - 10.3390/ma13071609

DO - 10.3390/ma13071609

M3 - Article

AN - SCOPUS:85082994734

VL - 13

SP - 1

EP - 15

JO - MATERIALS

JF - MATERIALS

SN - 1996-1944

IS - 7

M1 - 1609

ER -