Decorative Concrete Makes "Moose Park"

By Tom Miller, President, Metal Forms Corp., as told to Ray I. Scroggins

A concrete pad forms the base of Metal Forms Corporation's "Moose Park," which was created recently as part of the company's efforts to beautify its surroundings and celebrate its 95th anniversary.

The park, an enclosed landscaped area adjacent to the company's plant in Milwaukee, Wis., is home to two large metal moose sculptures that stand more than six feet high and weigh nearly 1,000 pounds each.

The contractor that prepared the site and installed the decorative concrete was Beyond Construction, LLC, of Butler, Wis., a mason-concrete company with more than 80 years of combined experience. The company specializes in both masonry and concrete, including decorative concrete hardscaping projects. Company owner Tonia Calo-Tilson says the firm's motto is creative construction innovations and solutions for today, tomorrow and beyond." She notes that the "Moose Park" project created an ideal situation to achieve tremendous results with a natural appearance, combining the contracting firm's expertise in the field with the versatile forms created by the park-site owner.

Site Preparation & Setup

To prepare the site, the contractor first removed loose soils in the area to receive the base. Next they installed six inches of #2 stone, with two inches of fine grade compacted over the top. A well-compacted foundation prevents settlement that would leave the concrete slab without proper support. It also helps drainage and can prevent soil erosion under the concrete. To accommodate immediate drainage, the stone was placed so it surrounds the concrete pad on all sides by 12 inches.

Erecting the Forms

Next, forms were erected to outline the desired free-form shape of the base, which was to be finished in decorative concrete. The reusable polyethylene forms are strong, yet lighter to handle than wood, easier to stake accurately, and suitable for straight or radius applications. On this project, their ability to handle the continuous curves made the job easier than using wood or Masonite. Calo-Tilson reports that the forms decreased installation time on the job by more than 50 percent. "They were very easy to install, easy to strip and clean," she points out. "They are a must-have form for all radius concrete forming."

Poly Meta Forms were erected to outline the shape of the decorative slab that was poured and finished by a coloring and stamping process. Continuous curves were created with the flexible yet strong forms.

The form sections were joined with end connectors and secured at the joints with metal slide pockets that were slid into the forms from either end. Twist pockets were added for support and spaced approximately three feet apart along the form's length. The curves were laid out and form pins were set as temporary "guide pins" on the inside. As the forms were bent around the radius, stakes were inserted into the stake pockets and driven into place. Form sections were joined together using end connections as a guide, and the guide pins were removed before pouring the concrete.

Once the forms were in place, six continuous 5/8" rebar sections were installed over 6" x 6" wire welded mesh to ensure longevity.

Preparing the Concrete

After the forms were ready and rebar in place, the concrete was placed, using a typical six-bag mix with low-chert stone. According to Calo-Tilson, these smaller stones allowed the stamping process to have a smoother surface, minimizing any stones that might try to protrude to the surface.

Once the "Brickform" Integral Color was added, the job was poured directly from the truck. After the initial striking was completed, the bull floating was done. Following that, the contractor used a rolling tamper to press down any stones near the surface before floating and edging the concrete. Calo-Tilson notes that edging with the Poly Meta Forms is much easier than edging along Masonite forms. The concrete pad was finished with a pitch of one-half inch per foot to allow surface water to drain off.

Coloring the Concrete

To achieve a uniform, homogeneous color, the crew used the integral color added to the batch as noted above. Shake-on hardeners, which are broadcast on to the fresh concrete and floated into the surface before imprinting, could have been used if more vibrant colors and a broader range of hues were desired. However the soft earth tones typically achieved with integral color were preferred here to reinforce the natural appearance of the surroundings.

Concrete used integral color (foreground), mixed into the concrete, to achieve a uniform, homogeneous color. A powdered release, seen in the background, prevented the stamping mats used to texture the concrete from sticking to the surface.

Using integral color also eliminated the work of floating the color into the surface during finishing, as would have been necessary with shake-on hardeners. Another benefit is that the color is permanent and homogeneous throughout the entire matrix.

Stamping the Concrete Surface

Before beginning the stamping process, it was necessary to monitor the concrete to determine when it reached the right stage of plasticity. Too soon and it would not have supported the weight of the workers or held the pattern's definition; too late and the stamping would have required more effort and produced insufficient texture. Stamping expert Terry Tilson says that, once all the bleed water had dissipated from the surface and it was possible to place one's palm on the concrete with a fair amount of weight, it was ready for stamping.

A stamping mat was placed on the surface of the concrete and pressure applied to impart the desired texture.

First, powdered release was applied to act as a bond breaker when using the stamping mats or skins to impart the surface texture to the finished slab. This prevented them from sticking to the concrete and disturbing the imprint texture and also helped achieve the desired color contrast.

Manufacturers offer a wide variety of patterns and tools for stamping, depending on the effect desired. A heavy stone pattern was chosen for this project due to its resemblance to a natural stone. A polyurethane stamping mat was chosen to impart the desired pattern in the surface of the concrete pad on which the Moose sculptures would be mounted.

Four different stamps were used. To begin the process, a mat was laid on the surface and then tamped down with a weighted tamper. As one area was completed, the mats were randomly moved, overlapping the previous stamp to achieve a random stone pattern.

When stamping the surface, it is generally best to stamp in the same sequence that the concrete was placed and finished, because the concrete that was placed first will reach the proper stage of plasticity sooner.

After the texture was impressed into the surface in one area, the mat was moved to another until the concrete pad was fully textured. The difference can be seen between the textured area (foreground) and the area still to be done.

The Final Results

After approximately 12 hours of curing time, the concrete was washed with a pressure washer to remove the excess powder left by the colored release agent. What remains is the darker color that can be seen in the creases of the stone pattern, which gives a very unique, natural effect. Calo-Tilson says there is no limit to the number of different release colors that could be used on a project.

Milwaukee Mayor Tom Barrett (left) and the company's President Tom Miller are shown on the textured decorative concrete pad with the two metal-sculptured moose in the company's new "Moose Park."

After the excess release agent was removed, control joints were saw-cut and the entire surface re-washed. When the concrete was completely dry, three curing compounds were applied. The last step was to apply a glazing compound that adds depth and durability to the finished product.

Appropriate mulch and plantings were added to showcase the moose sculptures, which were then installed to complete the project. Afterward, as part of the company's 95th birthday celebration, the company held an open house and dedication of "Moose Park" on the company grounds. One of the highlights was a speech given by Milwaukee Mayor Tom Barrett.

The moose sculptures were designed and created by Larry Oleson, the company's general manager of manufacturing. They feature spring-loaded heads that can move in a strong breeze.