A practical approach for reducing the risk of plastic shrinkage cracking of concrete

  • Sadegh Ghourchian Empa
  • Mateusz Wyrzykowski Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
  • Pietro Lura Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland

Abstract

In this letter, a conventional method for mitigation of plastic shrinkage of fresh concrete based on comparing bleeding and evaporation rates (the former based on the commonly observed values of bleeding rate and the latter estimated by means of the commonly-used ACI nomograph) is critically assessed. It is shown that even if the initial bleeding rates are sufficiently high (i.e. higher than the evaporation rates), cracking may still occur if all the bleed water is lost by evaporation between the times of initial and final set, leading to the rise of capillary pressure. An alternative and more conservative method should be thus based on the total (accumulated) amount of bleed water compared to the total amount of evaporated water. The former should take into account the concrete’s properties and the geometry of the member, while the latter can be assumed based on the nomograph method.

Plastic shrinkage cracks appearing on the concrete surface few hours after placement. Photo courtesy of Dr. Andreas Leemann, Empa
Published
2017-12-19
How to Cite
GHOURCHIAN, Sadegh; WYRZYKOWSKI, Mateusz; LURA, Pietro. A practical approach for reducing the risk of plastic shrinkage cracking of concrete. RILEM Technical Letters, [S.l.], v. 2, p. 40-44, dec. 2017. ISSN 2518-0231. Available at: <https://letters.rilem.net/index.php/rilem/article/view/45>. Date accessed: 26 apr. 2018. doi: https://doi.org/10.21809/rilemtechlett.2017.45.
Section
Articles