Award: Innovative Applications
Owner: Nucor Steel of Florida, Inc.
Contractor: Associated Brigham Contractors Inc.
Concrete: Jahna Concrete Inc.
Slag Cement: Argos USA
Nucor Steel Florida Inc. is a $240M investment by Nucor Corporation to build a reinforcing bar micro-mill in Frostproof, Polk County, FL. The new mill will create approximately 235 full time jobs and 450 temporary construction jobs. When up and running at the end of 2020, the mill will produce 350,000 tons of reinforcing bar annually to service the Florida construction market. The reinforcing bar will be produced from 100% recycled scrap metal. The plant uses electric arc furnaces to melt the scrap steel, so they don’t have big smoke stacks associated with older generation plants.
As a large recycler in North America and a diverse steel and steel products company, Nucor is proud to expand its footprint beyond the already 400+ Nucor team members currently operating in Florida.
Nucor has about two dozen plants around the country that produce 22 million tons of steel each year.
The project is located in the heart of Florida and most of the large concrete placements took place during the summer with temperatures in the 90s. The goal was to reduce thermal stress of concrete associated with ambient conditions, improve resistance to aggressive chemicals, and higher long-term compressive strengths. A concrete mixture design with 50% ground granulated blast furnace slag cement was used to mitigate some of these concerns, but also to take advantage of other benefits of using slag cement in concrete such as better workability, easier finishability, lower permeability, and a more consistent mixture.
Slag cement helped exceed the specified compressive strength of 4000 psi (28 MPa) in 28 days in a 50% replacement mixture with 540 lb (240 kg) of cementitious material and with a 0.49 max w/cm ratio.
Large lightweight concrete tanks were poured and moved to specific locations and set underground. The purpose of the tanks was to cool the recycled water during the manufacturing process.
The 4000 psi lightweight concrete mixture had a 30% slag cement replacement with 640 lb (290 kg) of total cementitious material, 48% lightweight aggregate, and 52% fine aggregate. In addition, a waterproofing admixture was added to the concrete mixture as an added waterproofing prevention.
% Slag Cement Replacement
% Portland Cement
% Other SCM (if applicable)
Coarse aggregate (#57) 60%/Fine aggregate (Sand) 40%
4900 psi (34 MPa)
6700 psi (46 MPa)