Concrete: It's not just for sidewalks any more
Originally published in the Santa Cruz Sentinel, October 1, 2011
Up against all the Smithsonians, monuments and memorials, the United States Botanic Garden is one of the lesser draws on the National Mall, tucked away on Independence Avenue, just a stone’s throw from the Capitol. Like most of the DC attractions, it’s free, informative and fascinating. But—unlike the rest of Washington—it’s a surprisingly crowd-free oasis.
US BOTANIC GARDEN: Here’s the ball in the United
States Botanic Garden that got me rolling.
Strolling along its pathways this summer, I was inspired by the decorative elements: upright plastic tubing that held gravel paths in place; colorful pyramidal plant supports; and multi-level arbors covered in plants from top to bottom. But what stirred me the most was a ball of concrete. Nesting at the base of a plant, this bowling ball-sized, cobalt blue sphere was a distinctive feature among the greens, pinks and reds of the surrounding regional plant-life.
ROCK ON BRAH: Terri Ryan recently took
first place at the Santa Cruz County Fair
for one of her signature concrete bras.
Concrete typically plays a utility role in most gardens—to invisibly anchor fences and decks, or just as subtly, provide low-cost but highly functional patios, sidewalks, curbs and retaining walls. Concrete is not there to be noticed, much less admired. It’s the stemware holding the fine wine: the clearer the glass the more its contents can be appreciated.When concrete is used in a decorative way, it’s often encrusted with grouted mosaic pieces or textured plaster. But the blue sphere showed me that relatively unadorned concrete can also be attractive.
To find out more about concrete, I contacted Terri Ryan, who recently took first place in the Capitola Soroptimists’ annual “Bras for a Cause” competition which benefits two local women’s support groups. Her imaginative entry, “Rock on Brah,” was constructed of molded concrete and rocks—a wonderful tribute to the possibilities of concrete.
COURTYARD ART: Terri Ryan’s courtyard is a concrete art showplace
featuring planters, pots, wall hangings, XXs and OOs, and pedestals,
all made from concrete.
A hair stylist with a degree in design, Terri said she started working with concrete about 6 or 7 years ago. “I needed to be around the house for my teenagers. These art projects are a great way of being home and being there for them,” she said. She learned much of her technique from Coleen Sands, whose mosaic work she had admired on her house numbers when passing by her home. The two have since become good friends and have regular “concrete play days” to get together and make things from concrete. (To see Colleen’s amazing mosaic work go to www.flickr.com/photos/colleensands/)
Terri’s Live Oak home and especially her yard is a showplace for her stepping stones, planters, pedestals, wall hangings and more—all made from concrete. Her courtyard workspace has shelves, bins and buckets full of objects and materials perfect for forming and shaping concrete. Inside her home she even has a bathroom backsplash make from concrete and river rocks.
On a recent Friday, she showed me how to make two concrete spheres and two stepping stones, while she continued work on a gigantic round planter formed around an inflated exercise ball. My much smaller spheres were shaped around a soccer ball and a school-yard rubber ball. We made stepping stones without a mold by adding a thin layer of concrete to the top of purchased concrete stepping stones, and stamping a circle into the concrete while still wet.
From working with Terri and from Sherri Warner Hunter’s book “Making Concrete Garden Ornaments” I got a better understanding of concrete’s properties.
- Concrete is a mixture of cement, water and aggregate.
- Aggregate is used to inexpensively bulk up the mixture. Common aggregates are sand and gravel, but lightweight material such as vermiculite, or more colorful material such as crushed shells or glass, can also be used. Rough, flat aggregates create a stronger bond than round, smooth ones, and smaller aggregates create a smoother textured concrete than larger ones.
- Water added to cement creates a paste that coats each piece of aggregate and hardens the mixture into a solid mass
- Chemical admixtures such as acrylic fortifier can also be added to the mix to increase moisture resistance, workability and durability.
- Curing is the process necessary for concrete to gain maximum strength. Concrete cures gradually in a moist, controlled environment. So, at the end of each work session, the concrete must be covered in plastic and kept moist for a minimum of three to five days, and out of direct sunlight and strong wind. Most of the strength is achieved in the first week, though strengthening may continue for decades.
What amazes me most about concrete is its versatility. Concrete is often shaped by being poured into a mold (casting). But it can also be pressed into or on top of a mold; or sculpted with the help of armature, which acts like a skeleton to support the form; or carved while wet or dry. By controlling the amount of water added, concrete can even be mixed to a consistency similar to clay for relief modeling. Surface treatments for concrete include incising, stamping, polishing, painting, staining, embedding and mosaicing.
Here are some suggestions for get started with concrete:
1. Seek out Sherri Warner Hunter’s books at the library—she will help you see concrete in a whole new way. Her 2005 book “Creative Concrete Ornaments for the Garden” will be available in paperback in March 2012.
2. Consider these new books: “Concrete Crafts” by author Alan Wycheck will show you how to make tiles, tabletops, stepping stones, bowls and planters cast from molds with lots of great step-by-step photos. “The Revolutionary Yardscape” by Matthew Levesque will give you radically new ideas for repurposing materials, such as garden walls made from wine bottle corks and pathways made with tumbled dishes. Levesque makes concrete bowls incorporating decorative materials such as tumbled glass, marbles, and even old keys.
3. Learn several different techniques for making concrete spheres by Googling “How to make a concrete sphere.”