A Teaching Moment at Indiana University Ferguson
Success of PLC in complex project inspired adoption through the region.
The Indiana University Ferguson International Center project required a white concrete to coordinate with the campus’s historic tan and gray limestone buildings, many of which date back to the original campus construction in the 1820s. The initial plan was to use white cement with imported materials for the four-level post-tension deck, which required architectural concrete on the outer perimeters and vertical elements.
The project team decided to switch to portland limestone cement (PLC), also known as Type IL cement, because it could achieve the needed color, durability and strength while being more budget friendly. The impact of COVID-19 also meant the university was looking for locally produced, more sustainable materials.
To match the color, the team completed 29 trial batches, making subtle adjustments each time. The extensive trials paid off, achieving a color match that met the university's stringent requirements and sharing knowledge across the entire project team in the process. A specialist in spectrophotometry helped ensure the color matching could be achieved, using corresponding L values assigned to each color puck and cured at different stages.
Also fairly unique to a post-tension deck project, two different mixes were used simultaneously. The project required different PSI levels for various components, including a 6,000 PSI post-tension deck concrete and 4,000 PSI for architectural walls. To achieve the 6,000 PSI, the team chose a 5,000 PSI design using slag and strength-enhancing admixtures.
Two different pumps were used to pour two different mix designs in a post-tensioned concrete deck. The greater mass of the center section was the 6,000 PSI non-air-entrained ash mix, using an F ash. With the cantilever section, there was a 6– to 8-foot section around the outside rim, which used a 5,000 PSI slag mix, air-entrained.
The limestone percentage across this project was approximately 11%. The careful blend ensured that the project met structural and aesthetic requirements, while providing substantial sustainability benefits. The team used several smaller mockups and stayed attentive to detail throughout the process, enabling them to move forward with confidence it would meet required standards and aesthetic requirements.
Following completion of the project, Irving Materials Inc. switched wholly to Type IL cement for projects in the southern Indiana region. The project serves as a model for how the construction industry can embrace the spirit of continuous learning and adopt newer materials and technologies, ultimately leading to a more efficient and sustainable built environment.
Project Team:
This project was a collaboration between:
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Weddle Bros. Building Group LLC
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Irving Materials Inc. (IMI), and
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Heidelberg Materials