RAAC panels can suddenly collapse before any warning of corrosion-induced surface cracking

TL;DR

This paper presents a computational model that predicts the sudden collapse of RAAC panels due to corrosion, even before surface cracking is visible, highlighting critical factors influencing structural failure.

Contribution

It introduces a novel corrosion modeling approach incorporating reactive transport equations and porosity-dependent diffusivity for RAAC panels.

Findings

RAAC panels can collapse suddenly without surface cracking.

Porosity significantly influences corrosion concealment.

The model maps conditions leading to sudden collapse.

Abstract

The collapse of reinforced autoclaved aerated concrete (RAAC) panels has attracted considerable public and academic interest. As detailed experimental data are not yet available and replicating the natural corrosion process requires years or decades, computational modelling is essential to understand under which conditions corrosion remains concealed. The very high porosity of RAAC is widely suspected to be a major contributing factor. However, current corrosion-induced cracking models are known to struggle with capturing the role of concrete porosity. To remedy this critical deficiency, we propose to enrich corrosion-induced cracking modelling with the analytical solution of reactive transport equations governing the precipitation of rust and a porosity-dependent description of diffusivity. With this, the corrosion concealment in RAAC panels is studied computationally for the first time, revealing that RAAC panels can suddenly collapse before any warning of corrosion-induced surface cracking and allowing to map the conditions most likely to result in sudden collapse.