Before its collapse on Aug. 1, 2007, the I-35W bridge was more than a structure that carried more than 140,000 vehicles per day. The bridge was a vital artery in the life of Minnesota's Twin Cities.
Rebuilding the span became an immediate priority to leaders at all levels of government. In addition to the emotional toll of 13 lost lives and 145 injuries, losing the vital cross-town link cost citizens more than $440,000 per day in additional user impacts, some economists estimated.
It was into this environment of urgency, community need, and to some extent, healing, that Cemstone Products' leadership team was thrust. Cemstone never faced the unanticipated need for action on such an important project, combined with the fast-track construction nature of this building endeavor. There was very little, if any, project preparation time.
Cemstone was in the desirable position, however, of availing itself of previously developed mixes, as well as existing and well-situated plants, equipment, and dedicated personnel. Cemstone's engineers were able to use proprietary mixture proportioning models to reliably and accurately predict later age properties of concrete mixtures.
The first hurdle was choosing aggregates. Minnesota Department of Transportation (Mn/Dot) engineers specified crushed granite for the coarse aggregate. Supplied from quarries in St. Cloud, Minn., the Cemstone production team had to plan and manage its production scheme to ensure adequate and consistent supply. Cemstone counted on an eight-week window during which they had to meeet much of the project's needs before shutting washing operations.