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Metropolitan Park Phase 7 and 8

Location: Arlington, Virginia

Award: High Performance

Project Team

Owner: Seneca Group Contractor: Clark Construction Group Architect: ZGF Architects, LLP Engineer: Thornton Tomasetti Concrete: Miller & Long Co., Inc Slag Cement: Holcim

Metropolitan Park Phase 7 and 8 is one of the two buildings that are the centerpiece of Amazon’s HQ2 project in Arlington, VA, USA. Sitting atop of a foundation consisting of more than 26,000 yd3 (19,880 m3) of mass concrete, the building consists of four levels of parking below grade, above which an office building continues up 24 levels. The mixtures were designed to enhance traditional concrete materials and reduce embodied carbon, which allowed Miller & Long to exceed the project’s goals of providing eco-friendly construction materials.

Slag cement was used as a SCM to lower the embodied carbon values for all concrete in Metro Parks 7 and 8. From the mass concrete of the mat foundations through the final slab, every mixture used by Miller & Long comprised significant quantities of slag cement.

Slag cement enabled Miller & Long to minimize the GWP of the concrete mixtures as required by the project specifications. The strength of concrete was not affected by the inclusion of as much as 75% of slag cement as the cementitious material in the mixtures.

Application Type

% Slag Cement Replacement


% Portland Cement


% Portland Limestone Cement

% Other SCM (if applicable)


#68 and concrete sand

Water/cement ratio


7-day strengths

5350 psi

28-day strengths

9,450 psi


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