Limits and possibilities of thermodynamic modelling of autogenous self-healing of concrete

Helmut-Schmidt University/ University of the Federal Armed Forces Hamburg, Institute of Engineering Materials and Building Preservation, Charlie-Mills-Straße 2, 22159 Hamburg, Germany

^* Corresponding author: lahmannd@hsu-hh.de

Abstract

Autogenous self-healing of water retaining concrete structures is included in Eurocode 1992-3 as a possibility to heal cracks up to a width of 200 μm without additional repair. In this self-healing scenario water flow through a crack should result in a progressive closure of the fracture, mainly due to CaCO₃ precipitation, when certain hydraulic gradients are met, the pH of the water is > 5.5 and the concentration of CO₂ in the water remains < 40 mg*L^-1. The material composition is not further restricted by the regulation. However, despite standardization, the healing effect seems to be random in practice, which requires further research, while experiments aimed at quantifying autogenous self-healing are expensive and time-consuming. Thermodynamic models could support in estimating the effect of different environments such as groundwater or seawater exposure on autogenous self-healing. Moreover, adjusting the water chemistry according to the conditions of different construction sites and changing the material design could easily be considered. In this study thermodynamic models of a hydrated CEM I 52.5 R paste that is exposed to either simulated groundwater or seawater are discussed concerning the influence on autogenous self-healing and compared to experimental and literature data.