Conduct comprehensive investigations, condition assessments and durability analyses of HPC concrete bridge decks
Infrastructure Management System
Assist in the design of a series of durable concrete mixtures to meet the 100-year service-life specification set forth by the Panama Canal Authority (ACP)
Durability modeling of concrete elements (e.g. caissons, piles, deck) using SIMCO's STADIUM® methodology
Multi-year repair plans, lifecycle cost analyses, monthly inspections and condition analyses for maintenance and repairs
STADIUM® is a numerical model dedicated to the prediction of chloride and other contaminant ingress in cementitious materials. STADIUM® allows owners, managers, engineers and contractors to reduce initial construction costs, avoid unnecessary inspection and maintenance costs, as well as prioritize capital expenditures. It also offers assistance for optimal material selection and identification of cost-effective rehabilitation strategies for a maximum service-life extension.
Contrary, to the first generation of chloride penetration models, such as Life-365™ and Duramodel™, STADIUM® is based on the most recent developments in ionic transport modeling and numerical solutions. Its finite-element calculation core can model the ingress of chloride and other species under different types of environmental conditions. The model also considers the complex interactions between contaminants penetrating the porous network of concrete and the hydrated phases of the cement paste. STADIUM® offers the possibility to take into account the chemical composition of local cements and supplementing admixtures such as silica fume, fly ash and slag.
The model also considers the impact of temperature and moisture content variations in materials on the rate of chloride ingress. It is thus possible to provide STADIUM® with time-dependent environmental conditions in order to simulate the effect of wetting and drying cycles on the chloride penetration rate, which allows engineers to simulate complex, but realistic exposure cases. The simulation of more accurate environmental conditions provides a better evaluation of the extent of chloride ingress and other contaminants in a structure during its service life.
STADIUM® requires adequate material parameters, therefore, a series of experimental methods were developed based on already existing standard procedures. These methods allow for the evaluation of the quality of concrete in order to assess the influence of various types of cements and admixtures as well as to consider material mixture proportions
The following table highlights the differences between STADIUM® and simplified modeling approaches based on Fick’s second law.
|Transport Equation||Based on the Extended Nernst-Planck model, accounts for:
||Fick’s second law of diffusion, valid under the following assumptions:
|Chemical Reactions||Handled by a separate module with the following characteristics:
A direct comparison can be made between both approaches. The following case presents both models that were used to predict chloride ingress in a 20-year old parking structure where de-icing salts are applied during winter.
The data was then used as input for each model in order to predict chloride ingress after 20 years. The results are presented in figure 1. In the present case, the simplified Fick’s law approach vastly overestimates the chloride ingress rate.
Figure 1 – Chloride ingress in a parking slab after 20 years of exposure to deicing salts
Over the years, STADIUM® has been extensively validated on the basis of laboratory and field data. This section shows examples of validation test cases performed by SIMCO that were either published in scientific papers/conferences or generated through different engineering projects. In all cases, the same procedure was used:
Figure 2 – 0.45 w/c OPC mix exposed to 0.5M NaCl (published: Samson E., Marchand J. (2006) Multiionic Approaches to Model Chloride Binding in Cementitious Materials, in Proceedings of the 2nd International Symposium on Advances in Concrete Through Science and Engineering (Quebec, Canada), Marchand et al. Eds, RILEM Proceedings 51, p. 101-122.)
Figure 3 – 0.65 w/c OPC mortar exposed 2 years to 0.5M NaCl in saturated and wetting/drying cycles (presented at the American Ceramic Society/Advanced Cement-Based Materials meeting, Nashville (USA), 2011.
Figure 4 – Chloride profile from 100-year old concrete (Pacific Walls of Panama Canal) exposed to seawater