IS-20

Ternary Concrete Mixtures With Slag Cement

What Are Ternary Concrete Mixtures?

Ternary concrete mixtures include three different cementitious materials. This report addresses those combinations of portland cement, slag cement, and a third cementitious material. The third component is often fly ash, but silica fume is not uncommon. ASTM C595 blended cement used in combination with a third cementitious material also is con- sidered a ternary mixture. Other materials in combination with portland and slag cement, such as metakaolin or rice husk ash, are not currently in common usage and will not be discussed here.

Slag cement has been used in ternary mixtures for decades. For example, the Empire State Building was constructed using combinations of slag cement, portland and lime in the masonry. Ternary mixtures using slag cement, fly ash and portland have stabilized soils and hazardous wastes.

What Are The Benefits Of A Ternary Mixture?

Ternary mixtures can be designed for:

  • High strength
  • Corrosion resistance
  • ASR resistance
  • Elimination of thermal cracking
  • Low permeability
  • Sulfate resistance

Compressive strengths exceeding 10,000 psi were achieved in 1989 in the construction of Scotia Plaza in Toronto. More recently, compressive strengths over 13,000 psi were attained in Reliant Stadium.

Cementitious Component Scotia Plaza Reliant Stadium
Lb / cu yd % of Total Cementitious Lb / cu yd % of Total Cementious
Portland 530 65% 450 50%
Slag Cement 228 28% 270 30%
Silica Fume 60 7% 0 0%
Fly Ash 0 0% 180 20%

Where Can Ternary Blends Be Used?

Ternary mixtures can be used—and have been used—in virtually any concrete application.

  • General construction (residential, commercial, industrial)
  • High performance concrete
  • Masonry and masonry units
  • Shotcrete
  • Paving
  • Precast concrete
  • Mass concrete

Can Ternary Blends Be Used In Exterior Concrete Exposed To Freezing And Thawing?

Ternary blends have been used in concrete exposed to freezing and thawing and de-icing chemicals. Proper air entrainment, adequate curing, and good concrete practices will maximize the ability of any concrete to resist freezing and thawing and de-icing chemicals. A number of mixture proportions have been used with good results. Some paving projects have performed for over five years in severe conditions with no apparent loss of durability.

What Mixture Proportion Should Be Used?

The optimum mixture proportions for ternary blends, as with other concrete, will be dependent on the final use of the con- crete, construction requirements and seasonal considerations. As with other concrete, cold weather will affect the early strength gain and mixture proportions may need to be adjusted to assure job-site performance.

In low W/CM applications such as paving, mixtures with 15 percent fly ash and 30 percent slag cement component have been used successfully. Key Tower in Cleveland, completed in 1990, used 65 percent portland, 27 percent slag cement and 7 percent silica fume to achieve strengths exceeding 14,000 psi.


Reliant Stadium (NFL) in Houston, which opened in 2002, used a portland-slag cement-fly ash mixture to achieve both high strength and low heat in its four massive "super columns," supporting the retractable roof.


In 1998, airfield pavements were constructed at the Minneapolis Airport using a portland blast-furnace slag blended cement consisting of 35% slag cement, with an addition of 10% Class C fly ash. Performance of the concrete has been excellent.


Structural concrete in the Key Tower (formerly Society Tower) in Cleveland achieved over 13,000 psi using a portland-slag cement-silica fume ternary mixture.

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