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

RILEM Technical Letters

article

Sadegh Ghourchian¹  Mateusz Wyrzykowski²  Pietro Lura² 

[1] Empa, Swiss Federal Laboratories for Materials Science and Technology;Institute for Building Materials (IfB)

关键词: Fresh concrete;    Plastic shrinkage cracking;    Evaporation rate;    Bleeding;    Crack mitigation;   

DOI  :  10.21809/rilemtechlett.2017.45

学科分类：社会科学、人文和艺术（综合）

来源: RILEM Publications SARL

【 摘 要 】

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.

【 授权许可】

CC BY