The Slag Cement Association (SCA) has been honoring the exceptional use of slag cement in concrete construction since 2010 with the Slag Cement Project of the Year Awards. This year’s awards ceremony took place at the ACI Spring Convention in Quebec City, Canada on Wednesday, March 28th during the session “Slag Cement in Durable Concrete”. SCA representatives presented the awards to winning teams in attendance and gave an overview of each project to session attendees.
New this year to the awards program is a research award category, attracting applications from students working on a wide range of projects exploring the role of slag cement in durable concrete construction.
“The SCA awards program has always been focused on honoring the innovative use of slag cement in durable concrete. Adding this research category to the lineup has been a great way to expand that concept while getting students involved.”
Ed Griffith, SCA Board President
The SCA was pleased to award 2 research projects this year. Both winners were able to attend the awards ceremony and had the opportunity to present a short overview of their projects to attendees.
Brief overviews of the projects are below with links to full descriptions, more photos, and videos
RESEARCH AWARD WINNERS:
The Beneficial Effect of Slag Cement on Low Temperature Sulfate Resistance of Concrete Produced with Portland-Limestone Cements and Slag
Student: Reza Mohammadi Ahani, University of Toronto
Portland-limestone cement with up to 15% interground limestone was included in the Canadian Standard A3000 for Hydraulic Cements in 2008. However, due to the lack of data on sulfate resistance of concrete especially the potential for thaumasite sulfate attack at low temperatures, the use of portland-limestone cement in concretes subjected to moderate or severe sulfate exposures, even when blended with supplementary cementitious materials (SCMs), such as slag, was not allowed.
In this experimental research, the sulfate resistance of fifty-three concrete mixtures produced with several combinations of portland and/or portland-limestone cements and SCMs including slag, silica fume, metakaolin, and fly ash was evaluated in both laboratory and field exposures at low temperatures by measuring changes in length, mass, and resonant frequency of concrete prisms as well as making visual inspections.
As an ultimate result of the research conducted, the Canadian A3000 and A23.1 standards have been changed to allow the use of Portland-limestone cement together with slag in sulfate exposures without any low-temperature testing or other restrictions. More specifically, the sulfate resistance of Portland cement + slag cement and Portland-limestone cement + slag cement concrete mixtures at w/cm ratios of 0.40 and 0.50 was found to be equal or better than that of traditional highly and moderately sulfate-resistant Portland and blended cements. A full overview and additional results on this project are available here, at the SCA website.
Evaluation of Ultra-High Performance Concrete Mix Designs for Use in Bridge Connections and Repair
Student: Amy McDaniel, Trevor Looney, University of Oklahoma
The outstanding strength and durability properties of ultra-high-performance concrete (UHPC) make it an ideal material for use in infrastructure applications. The purpose of this study was to develop UHPC mix designs that were cost-effective and able to obtain comparable properties to commercially available products, then evaluate the performance of the best mix design when used as a joint material.
First, UHPC mix designs were evaluated using materials easily obtained in the state of Oklahoma such as Type I and III cement, Class C fly ash, VCAS 140 White Pozzolans produced by Vitro Materials, slag cement, silica fume, masonry sand, and a high-range water reducer. Then, the properties of the best three mix designs were studied by evaluating compressive strength, modulus of rupture, modulus of elasticity, and abrasion resistance. Two of the three best performing mixes contained large quantities of slag cement (30 and 40%, respectively). Lastly, the best performing developed mix design was used as a joint material and full-scale panels connected by this material was tested to assess ultimate capacity and fatigue behavior. The test results showed that the UHPC mix design developed had comparable performance as a joint material to available commercial products.
The optimistic results obtained from this study show that UHPC with comparable performance to proprietary blends can be developed using materials readily available in Oklahoma. Slag cement played a large role in the development of these mix designs. Even with large replacement levels up to 40% of total cementitious content, the developed UHPC mix designs performed as well as Ductal® in most tested applications. Furthermore, the slag cement improved the workability and ease of placement over conventional UHPC while reducing the overall cost of the mixes. ODOT has also commissioned the University of Oklahoma to continue testing on mix J3 (which contains 30% slag cement) in a second phase of research to further prove its effectiveness as a repair material for concrete bridges.
CONSTRUCTION AWARD WINNERS:
National Veterans Museum, Columbus Ohio
Member Company: Skyway
Award Category: Architectural
With over 8,000 cubic yards of concrete, the building’s frame is one of the most complex concrete structures to ever be built in Ohio. All mixes on this project utilized slag cement, varying between 35%-65% replacement. Slag cement was used for its aesthetically pleasing finish, lighter color, strength and lowered permeability. The mass concrete placements were successful due to using slag cement to lower initial heat of hydration. Almost all mixes made design strength within 7 days.
The Virage Bayshore
Member Company: Argos
Award Category: Architectural
Slag cement was used on this project in multiple mix designs, however, the most important usage was on the 10,000 psi mix used for columns. Argos was able to use a 50% slag cement (grade 120) mix to achieve the high strength requirements and maintain concrete temperatures below 100 F during the hot summer months in Tampa. The strength gain along with cooler concrete temperatures were the most important contributions slag cement made on this project.
Indian Lake Spillway
Member Company: St. Marys Cement
Award Category: Durability
The Indian Lake Spillway is the second largest labyrinth style dam in the United States and largest east of the Mississippi. Indian Lake's storage capacity at principal elevation is 15 Billion gallons of water spanning across 5,063 acres. Ohio Ready Mix successfully supplied over 7,300 cubic yards of mass concrete to this project. Both mix designs required the use of 50% slag for temperature control, ASR mitigation, and to help reduce shrinkage.
Louisville Metropolitan Sewer Water Basin
Member Company: Skyway Cement
Award Category: Durability
This MSD basin was created to collect rain water runoff to help control flooding. Slag cement was used at a 50% replacement rate in mass concrete and self-consolidating concrete to help reduce heat of hydration.
SFO Long Term Parking Structure:
Member Company: Lehigh Southwest Cement Co.
Award Category: Green Design
San Francisco International Airport, owner of this green concrete project, set out to demonstrate its leadership in sustainable building by achieving LEED credits for the new parking structure using concrete made with supplemental cementitious materials, specifically slag cement. While the specs originally called for fly ash, Graniterock suggested slag would work better because of its efficient set time.
Tappan Zee Bridge
Member Company: LafargeHolcim
Award Category: High Performance
The Tappan Zee Bridge, officially named the Governor Mario M. Cuomo Bridge after former New York Governor Mario Cuomo, is a twin cable-stayed bridge built to replace the original Tappan Zee Bridge over New York's Hudson River. Slag Cement was used for low heat in mass concrete applications (67% slag cement) and for achieving 100-year service life (FIB modeling was used).
Charlevoix Cement Plant Expansion and Silo Installation
Member Company: St. Marys Cement
Award Category: High Performance Concrete
The most innovative use of slag on the expansion project was the 23,000 ton blending silo. It holds enough raw feed for 2 Yi days of production. It stands 160 feet tall and is 78 feet in diameter. It was poured in a continuous slip form pour that last several days.
Meadow Lake Wind Farm
Member Company: Lafarge Holcim
Award Category: Innovative Applications
Meadow Lake Wind Farm, Phase VI, consists of 61 wind turbines. Slag cement was employed to better control the temperature rise of the mass concrete foundations for the wind turbines. Thermocouples were placed into the mass concrete and no foundation could exceed 160 °F. Slag cement was also utilized at 30% to mitigate alkali silica reaction (ASR) concerns and to aide with the overall consistency of the concrete delivered to the project.
Ottawa River Storage Facility
Member Company: LafargeHolcim
Award Category: Sustainability
Slag Cement was used in the creation of this underground, 36.3-million-gallon tank that was placed under a public park. Slag was used to prevent thermal cracking in the thicker segments of the floor, walls and roof. Slag was also used to decrease the permeability of the concrete floor, walls and columns and to provide sulfate resistance against the storm/sewage waste water.
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The SCA has been running its annual awards program since 2010. Current and past award winners are featured on the SCA website, slagcement.org. The Slag Cement Association represents companies that produce and ship slag cement (ground granulated blast furnace slag) though the USA. The Slag Cement Association serves as the leading source of knowledge for slag cement and slag blended cements through promotion, education, and technology development.