August 1997 Table of Contents

Features Exposed Aggregate Blossoms in Botanical Garden

Is it possible to create exposed-aggregate walkways with enough rock at the surface to make pedestrians think they're walking on gravel paths? Ahal Contracting Co., St. Louis, proved the task can be done when its crews placed 40,000 square feet of exposed-aggregate walkways for the Missouri Botanical Garden's Boxwood Garden and the Kemper Center for Home Gardening. The four different concrete mix designs used for the project contained aggregate concentrations higher than those found in the typical exposed-aggregate mix. Read more

Features Resurfacing Systems Revitalize Old Concrete

Available in an endless array of colors and patterns, polymer-modified cementitious resurfacing systems can add beauty to sidewalks, driveways, patios, pool decks and other existing concrete surfaces. The systems can even be used on vertical surfaces, such as walls and step risers. The resurfacing components include a liquid polymer, color additive, and premixed portland cement and fine aggregate. The materials are mixed onsite with water, then applied in one or two coats. You can use the resurfacing alone or with paper or plastic templates, which allow you to create a variety of brick and stone patterns. Read more

Features Artist's Designs Enhance Flatwork in Public Places

Thanks to the creative talent of artist Vicki Scuri, the colorful concrete flatwork of Play Ray Plaza at Seattle's Key Arena has replaced what was once a dismal asphalt entry resembling a parking lot. In recent years, Scuri's work in concrete has provided the aesthetic concept for this and other precast and cast-in-place projects throughout the West. Read more

Features Tax-Deferred Equipment Exchanges

One of the most effective tax-saving tools, a like-kind tax-deferred exchange, is finally gaining widespread attention in the construction industry. Construction equipment is largely, if not entirely, depreciated by the time you replace it. But since the equipment retains significant market value, its sale often results in current-year taxable income, even if you sell the equipment at a loss. By using a like-kind exchange, you can defer those taxes for years and use the cash to help purchase replacement equipment. You don't have to purchase the new equipment from the buyer of your old equipment, and the two transactions can occur up to 180 days apart. Read more

Problem Clinic Subbases Not Needed Beneath Most Concrete Streets and Low-Volume Highways

Is a granular base needed beneath city streets or parking lots that will be paved with concrete? Some specifications require a subbase and some don't. If one is needed, how thick should it be? Read more

Problem Clinic Placing Concrete Without Damaging Lawns

I'm a remodeling contractor who builds a lot of additions, usually at the rear of an existing house. We pour our own footings, foundations, and flatwork, but often the 10-cubic-yard ready mixed concrete trucks are too heavy or too big to get to the home's Read more

Problem Clinic Effects of a Calcium-Chloride Overdose

We accidentally added 6% calcium chloride by weight of cement to a truckload of concrete that went into a residential driveway placed during cold weather. Though the contractor had no trouble placing and finishing the concrete, he is concerned about low c Read more

Problem Clinic Can Power Trowel Blades Overlap Hardened Concrete?

I've read about false curl, which results when concrete settles in the middle of a strip pour, making the fresh concrete surface lower than the side forms. Read more

Problem Clinic Can Heat of Hydration Melt Expanded Polystyrene?

We're placing massive concrete walls using forms that have expanded polystyrene form liners. The wall sections are 25 feet high, 32 feet long and 12 to 24 inches thick. Read more

Problem Clinic What Are Slip Sheets For Slabs on Grade?

While we were getting ready to build some slabs that required protection against moisture intrusion, we searched for all the information we could find on vapor barriers. Looking through the American Concrete Institute booklet Slabs on Grade (2nd ed.), we Read more

Problem Clinic Steel Troweling Exterior Air-Entrained Concrete

I've heard that it's not a good idea to use a steel-trowel finish for air-entrained exterior flatwork. However, I can't find any references that specifically recommend avoiding this practice. Read more

Problem Clinic Mixing Time for Jobsite-Added Accelerator

What's the required mixing time and drum speed when an accelerator is added to ready-mixed concrete at the jobsite? Read more

Problem Clinic Correcting a Wet Garage Floor

I live in Louisiana. Many times my garage and shop floors become very wet and slippery during the winter, when the air temperature changes quickly from cold to warm. What can be done to concrete floors to prevent this from happening? I'm also installing a Read more

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