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Hillman Garage

Location: Annapolis, Maryland

Award: Durability

Project Team

Owner: City of Annapolis Contractor: Whiting-Turner

Architect: BCT Design Group

Engineer: Walker Engineering

Concrete: BARR Concrete, supplied by Chaney Enterprises Slag Cement: Heidelberg Materials

The Hillman Garage located in downtown historic Annapolis, MD, USA, is a 190,000 ft2 (18,000 m2) facility that replaced a 50-year-old parking structure on the same site. This 590-space facility has solar panels capable of supplying 100% of the facility’s energy needs; a stormwater recovery system that prevents stormwater from affecting the neighboring business district; and license plate readers that allow gateless parking and minimize fuel-wasting delays during entries and exits.

The project team customized low-carbon concrete mixtures to include 50% slag cement and ASTM C595 Type IL cement. The combination of slag cement and portland-limestone cement helped with the project’s demanding construction schedule, and it met the durability requirements for a design service life of 75 years. The light color of the concrete pavement made also provides aesthetic and social benefits.

The Hillman Parking Garage is a keystone project within the historic Annapolis downtown district. It includes more than five parking levels, EV charging stations, bike racks, and open access to street level pedestrian walkways that will serve as a gathering space for community events and help revitalize the surrounding city space.

Application Type

% Slag Cement Replacement


% Portland Cement

% Portland Limestone Cement


% Other SCM (if applicable)


57 Stone, 8 stone & C33

Water/cement ratio

.44, .38

7-day strengths

3997 psi, 5176 psi

28-day strengths

5581 psi, 7361 psi


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