Using Concrete Service Life Prediction Software to Enhance Durability and Reduce Cost in Precast Parking Garage Design

Parking garages are unique building structures in that they are often open to the environment and exposed to deicing chemicals, making them susceptible to deterioration, particularly through the corrosion of reinforcing steel. The exposures parking garages face make it important to design them specifically for durability and to consider long-term costs and performance in their design. Life-365 is a software tool developed to aid in the service life–based design of reinforced concrete structures and to calculate the costs of ownership over the life span of the structure. This study was conducted to investigate the effects of different protection strategies on service life and life cycle cost (LCC) for a concrete slab in a parking garage and to assess the utility of Life-365 in helping designers and owners of these structures most effectively manage and allocate the resources they have. The protection strategies investigated are decisions made at the design stage including increasing the concrete cover distance to the embedded steel, decreasing the w:cm ratio, using supplementary cementitious materials (SCMs) in the concrete mixture, using epoxy-coated steel, and using membranes or sealers on the concrete slab surface. Results show that using SCMs and increasing the concrete cover distance were the best in enhancing slab durability and reducing total costs at the end of the design life. The study also demonstrates that, while Life-365 is well suited to assisting in the initial design of reinforced concrete structures, it has very limited utility in planning and projecting the usefulness of preventive maintenance.