South Bend, IN
Owner: University of Notre Dame
Contractor: Reith-Riley Construction
Engineer: KFI Engineering
Slag Cement: Ozinga
In this project the use of slag cement allowed the ability to meet or exceed required specifications. Due to the continued late strength gains of slag cement, the resulting 8,000 PSI concrete will be durable enough to stand up to the constant water pressure. The mix could never exceed 160°F due to curing conditions so a high cement replacement, 80%, aided in a lower heat of hydration during set times. The mix also possessed the exact workability and uniformity needed to be pumped 50 feet underground and still consolidate effectively. The speed of placement was critical as 6000+ cubic yards of ready mix were needed. A massive amount of rebar was used so additional benefits such as corrosion resistance and ASR mitigation all factored into the use of slag cement. Since this permanent structure will be in direct contact with water it was important to use an SCM that had resiliency against sulfate attack. The high dosage rate allowed for this along with reducing permeability of the concrete. Slag cements compatibility with Portland cement and other admixtures helped create a unique mix design for this application without sacrificing performance for cost for the life cycle of the project and future maintenance of the structure.
Over the course of three years in quality control, research and development, Ozinga tested and designed a mix meeting all strict temperature, strength, durability, and cost requirements.
To maximize and embrace the sustainable aspect of this project, part of the goal was not only to construct as renewable energy source or Notre Dame, but to also use sustainable raw materials where possible. The opportunity to showcase SCMs performance at such a replacement level is truly unprecedented. The sophisticated mix required needed a very low water-to-cement ratio, a viscosity modifier to ensure cohesiveness and a large slump that would be workable and pumpable in combination with the steel rebar, without exceeding budget. This mass concrete (foundation, caissons, seawall) application would be in direct contact with water and would need to hold up to high external forces pressure from the river.
In 2015, the University of Notre Dame renewed a commitment to reduce their carbon emissions in an effort to become better stewards of the Earth. Their plan is designed to cut its carbon footprint in half by 2030. The St. Joseph River dam in downtown South Bend will be one of the major contributors to this initiative by capturing the energy of falling water to generate electricity and contribute 7% of the power used on campus. All stakeholders involved were tasked with, and committed to, fully utilize the river to construct an underground 2.5-megawatt hydroelectric facility that will offset nearly 9,700 tons of carbon dioxide annually.
South Bend’s history is forever linked with the St. Joseph River. It was used for mechanical and electric power generation. When other energy sources become more cost effective the river was abandoned. This project is returning to the source of South Bend’s growth utilizing the river’s sustainable power. The sheer size and length of planning, permitting, development of the mix, and pre-construction involving numerous companies and organizations is incredible. The result is additionally impressive because it not only benefits the University of Notre Dame’s long-term goals, but it will enrich the city of South Bend providing a park for the community to gather and a landmark for future development. All parties involved were committed to the betterment of our world through the reduction of both embodied and operational carbon emissions.
% Slag Cement Replacement
% Portland Cement
% Portland Limestone Cement
% Other SCM (if applicable)