Memorializing 9/11 with an Engraved Concrete Map

On a hot windy May morning near Colorado Springs, Dan Zigterman, production manager at Denver-based Colorado Hardscapes Inc., walked alongside the premium flooring division manager, Chuck Lau. Each carries more than 30 years of construction experience under his belt, so very little catches either one of them off guard. As the wind blew, the two men walked with their heads down, studying the concrete pavement and saw cuts of newly placed concrete. They discussed layout and schedule as they do with any ordinary job. They each studied the finished slab and planned how to transform it into the image they saw on the plans. As they walked and Dan talked, Chuck’s gaze moved up the horizon until his eye caught it. There, standing lonely in the hot morning wind, leaned a single shard from the World Trade Center of New York City. All other sounds around him grew mute.

Dan continued to talk, not realizing his colleague had paused.

As the wind blew, Chuck heard Dan’s voice again and apologized. He had been caught up in the moment and in reverence of the memorial ground upon which they stood.

Schriever Air Force Base had decided to create a memorial in remembrance of the events that occurred on September 11, 2001. With Schriever’s engineers and the landscape architecture direction of DHM Design, out of Denver, the plan came to fruition. The base hired Colorado Springs-based DWG & Associates as the general contractor, which in turn hired Colorado Hardscapes for the decorative concrete scope.

The simple yet powerful design of this memorial included the piece of wreckage from the World Trade Center and a map of the Northeast coastline of the United States on concrete pavement that approaches the tattered beam. The map identifies the coastline and the three crash sites of that dreadful date.

On sensitive ground
The rigmarole of working on a government project involves many issues, including prevailing wages, security badging of all site employees and testing of concrete mix designs. Having worked on several military and government projects in the past, Colorado Hardscapes came prepared. The United States Air Force Academy in Colorado Springs had previously approved a special mix of Colorado Hardscapes’ house-made Sandscape Texture, and the finish translated smoothly to this application at Schriever Air Force Base.

Because of the sensitive nature of the memorial, sampling and approval of the finishes and layout was crucial for this project. Colorado Hardscapes’ research and development department created a sample with the integrally colored Sandscape concrete, Bomanite’s Micro-Top cementitious overlay, saw cuts and caulk for review and approval before any work began.

After approval of the sample and site work by DWG, Colorado Hardscapes placed Yellowstone integrally colored Sandscape texture as the base slab for the memorial paving. The 6-inch concrete slab contained No. 4 rebar 18 inches on center along with fiber mesh for reinforcement. The overall jointing pattern for the slab was a 4-by-4-foot grid.

After the 28-day cure period, they returned to outline the Eastern shoreline, major lakes and state lines. After careful layout with AutoCAD and the printing of full-sized plans, Colorado Hardscapes’ men battled the high winds and taped the plans to the cured Sandscape concrete. The crew used tape to outline the state lines and shorelines as identified on the plans. With several maps and references, they adjusted the lines to ensure precision. “For a project like this, it just had to be perfect, so that anyone standing there would be able to identify exactly where they were,” says Lau.

From there, the crew cut the state lines with V-cuts and taped down plastic. With the water area and shoreline exposed, they installed a blue Micro-Top finish to simulate the Atlantic Ocean and lakes. They applied the Micro-Top in a Sandscape-type finish, which they dubbed Micro-Top ST. The crews started with a base coat of dark blue, then applied additional layers of light blue and green to reflect the continental shelves of the ocean floor. The layering technique of Micro-Top, along with the texture, gave the finish a more artful appearance — and yet, a more cost-effective installation — than blue integrally colored concrete.

Colorado Hardscapes’ crews carefully stripped the tape and plastic to reveal a crisp shoreline. Each of the saw-cut state boundaries received black caulk for emphasis. Three 12-inch-wide circles were precisely placed with yellow Micro-Top, one at the World Trade Center location, one at the Flight 93 crash site in Pennsylvania, and one at the Pentagon. Upon final completion, the entire slab received our in-house blend of Okon sealer to help protect the finished art piece.

Colorado Hardscapes works on many spectacular and artful projects, but installing a 9/11 memorial on an Air Force base in Colorado Springs was a unique and humbling experience.