TY - CHAP

T1 - Comparison of Water-Isopropanol Replacement and Lyophilisation for Hydration Stop of Cementitious Suspensions

AU - Kißling, Patrick André

AU - Cotardo, Dario

AU - von Bronk, Tabea

AU - Lohaus, Ludger

AU - Bigall, Nadja-Carola

N1 - Funding information: Acknowledgments. Financial support from the German Research Foundation (DFG) within the framework of SPP 2005 (BI 1708/5-1 and LO 751/26-1), as well as from the project BI 1708/4-1.

PY - 2019/8/25

Y1 - 2019/8/25

N2 - For modern concrete technology, rheology is crucial for characterizing the properties of fresh concrete on the basis of physically defined parameters. These properties can be influenced by many factors, but have an effect on paste level predominantly. To obtain an understanding of influencing factors such as the underlying kinetics and mechanisms at the initial colloidal scale a time variant analysis of cementitious suspensions is needed. In this article, a method to stop the hydration process of cementitious suspensions at any time by gradual water-isopropanol replacement and lyophilisation is demonstrated. Therefore, three different methods for hydration stop are investigated, namely water-isopropanol exchange, lyophilisation as well as a combination of both, and compared to pristine (non-reacted) cement particles. Analysis of dried samples leads to the observation that direct lyophilisation leads to particles of similar size as the pristine cement particles. Water-isopropanol replacement as well as water-isopropanol exchange with subsequent lyophilisation, instead, leads to a very broad particle size distribution with larger particles, which might be attributed to secondary agglomerations of particles. We further investigate the three different hydration stop methods by evaluating the pore size distribution by means of nitrogen physisorption. Additionally, scanning electron microscopy (SEM) as an imaging method is used.

AB - For modern concrete technology, rheology is crucial for characterizing the properties of fresh concrete on the basis of physically defined parameters. These properties can be influenced by many factors, but have an effect on paste level predominantly. To obtain an understanding of influencing factors such as the underlying kinetics and mechanisms at the initial colloidal scale a time variant analysis of cementitious suspensions is needed. In this article, a method to stop the hydration process of cementitious suspensions at any time by gradual water-isopropanol replacement and lyophilisation is demonstrated. Therefore, three different methods for hydration stop are investigated, namely water-isopropanol exchange, lyophilisation as well as a combination of both, and compared to pristine (non-reacted) cement particles. Analysis of dried samples leads to the observation that direct lyophilisation leads to particles of similar size as the pristine cement particles. Water-isopropanol replacement as well as water-isopropanol exchange with subsequent lyophilisation, instead, leads to a very broad particle size distribution with larger particles, which might be attributed to secondary agglomerations of particles. We further investigate the three different hydration stop methods by evaluating the pore size distribution by means of nitrogen physisorption. Additionally, scanning electron microscopy (SEM) as an imaging method is used.

KW - Cementitious suspension

KW - Freeze drying/lyophilisation

KW - Hydration stop

KW - Rheology

KW - Time variant analysis

UR - http://www.scopus.com/inward/record.url?scp=85071476092&partnerID=8YFLogxK

U2 - 10.1007/978-3-030-22566-7_71

DO - 10.1007/978-3-030-22566-7_71

M3 - Contribution to book/anthology

AN - SCOPUS:85071476092

SN - 978-3-030-22565-0

SN - 978-3-030-22568-1

T3 - RILEM Bookseries

SP - 610

EP - 618

BT - Rheology and Processing of Construction Materials

A2 - Mechtcherine, Viktor

A2 - Khayat, Kamal

A2 - Secrieru, Egor

PB - Springer Netherlands

ER -