Launch Slideshow

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Decking the Halls

Decking the Halls

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    The ornaments, with hangers inserted, should set for a day before removing them from the molds.

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Concrete Christmas Ornament Instructions

It was early fall and the arid Arizona landscape was in for several months of 100-plus degree heat. But the holiday spirit was in the air at the Del E. Webb School of Construction at Arizona State University in Tempe.

I proposed an unusual project for students in the school's Concrete Industry Management (CIM) program. Making concrete Christmas ornaments would not only be fun. But the project would also expose students to several recent developments in concrete technology, including insulating concrete, decorative concrete, and fiber concrete.

The eight students, who took the elective class last fall, accepted the challenge. As a result of the project, they would learn about several aspects of the industry, including:

  • Using integral color.
  • The role of fibers in concrete with discussion on the various types of dosages and fibers.
  • Slip form versus cast-in-place forms.
  • The role of water in achieving strength and consistent color.
  • Mix designs that people unfamiliar with concrete can understand and reproduce.
  • Lightweight concrete.
  • During the first class, students received handouts on perlite and vermiculite aggregates, color charts on various pigments available from Solomon Colors, and a notebook on various types of fibers produced by Forta Fibers.

    The students worked independently and did the projects in stages, including form selection, casting techniques, and simple mix design. The forms varied from cookie cutters (slip form method) to gelatin and candy molds (cast-in-place).

    Students tried both the vermiculite and perlite aggregates. Vermiculite was graded as a fine sand and allowed the students to use a more detailed mold. These were slightly lighter. Most preferred this as the aggregate.

    They tried various mix designs. After several trials, most found that to achieve the toughness, strength, placeability, and necessary consistency, a three- to four-part vermiculite to one-part of cement and water was added to achieve the consistency of a stiff cookie dough.

    Finally, just as the Christmas season started, the students presented their final report and ornaments to CIM staff and industry professionals. They made six ornaments available for inspection, gave a five-minute presentation showing their procedures, and gave a marketing plan explaining why someone should use their ornaments.

    This project has led to two other activities. In February, the Del E. Webb School of Construction hosted a dinner for high school teachers and counselors where they learned about the CIM program. Also, the Arizona State University student chapter of ACI used the same concrete mix design and procedure to make the holiday ornaments for a red floating concrete heart centerpiece, which will illustrate concrete's versatility.

    The adviser for the Webb School of Construction has asked that the class be repeated this fall. In her opinion, the project provides an excellent introduction to concrete and encourages students to consider the CIM program as a major.

    I would like to thank Legacy Decorative Concrete, Solomon Colors, and Forta Fibers for their support in making the project a success.

    Luke M. Snell is the director of the Concrete Industry Management program at Arizona State University, Tempe. For more, visit http://construction.asu.edu.