Project: I-64 Internally cured bridge at State Road 61 - Lynnville, IN
Contractor: Ragle, Inc. - Newburgh, IN
Project obstacles and solutions: INDOT was replacing aging bridges along I-64. This included the State Road 61 Bridge that crosses the interstate at Lynnville, Indiana. Ragle, Inc. was hired to rebuild the bridge. INDOT specified an internally cured concrete mix. Internally cured concrete is designed with a water-saturated aggregate that hydrates the cementitous materials in the mix over a long period of time. This longer cure time produces a stronger compressive strength and helps extend the life of bridges.
Producing internally cured concrete requires a lot of preparation before the pour. This mix incorporates a lightweight fine sand. The amount of lightweight fine aggregate required for internal curing is calculated and replaces an equal volume of concrete sand. Lightweight aggregates are heated up in a kiln to produce air pockets. These voids will fill up with water which will, in turn, hydrate the cement in the mix. Three days prior to a pour, these lightweight fine aggregates had to be soaked in water. This meant that the pouring schedule had to be precise - it could not be moved up or back. IMI worked with Ragle to meet construction scheduling issues.
IMI QC/QA did extensive testing on the raw materials used in this mix. The bridge used a blended cementitious of Portland cement, slag and micro-silica fume. IMI tested the concrete alongside INDOT inspectors to ensure the mix was correct. This required specific slumps for the different concrete components of the bridge. The internally cured concrete was used on the deck, the approaches and the slip-form rails. IMI supplied a total of 650 yards of internally cured concrete for this project.
In 2016, this project was awarded an Outstanding Concrete Achievement Award from the Indiana Ready Mix Concrete Association for infrastructure innovation.
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