October 1993 Table of Contents

Features Avoiding Form Failures

Better safe than sorry - the old adage applies nowhere better than to formwork for concrete. Educate workers to construction site safety so they don't take unnecessary risks. Discussing chains of events that cause forms to fails is one way to help the crew erect systems that work well. Organize sessions where experienced workers can pass along their knowledge to younger workers. And alert all workers to these leading causes of formwork failures: Read more

Features Forms for Concrete Columns

Common materials for column forms include plywood, paperboard, plastic, and steel. Most systems produce simple round or rectangular columns. However, almost any column design is possible by building custom wood forms, modifying existing forms, or using precision-cut polystyrene forms or form inserts. If architectural specifications require smooth, unlined column surfaces, forms are available with smooth inner surfaces or seamless liners. Read more

Features Nonmetallic Form Ties

Composites, also known as fiber-reinforced plastics (FRP), have found a niche in the aerospace, automotive, and sporting equipment industries. More recent developments show they have promise for use as structural materials, including reinforcement for concrete. Read more

Features Testing Hardened Concrete

The proof of concrete quality is field performance under actual loading and environmental conditions. But before concrete experiences much of this exposure, it's necessary to determine its acceptability and make projections about its long-term performance. These judgements are based, in part, on the results of tests performed on hardened concrete. Standardized tests are available for: Read more

Features First Reinforced Concrete Skyscraper in the U.S.

When it was completed in 1903 in Cincinnati, the Ingalls Building became the tallest reinforced concrete building in the United States. Although its overall dimensions were only 50 x 100 feet, the 16-story structure was twice as tall as any previous reinforced concrete building. It offered economy, fire safety, strength, and durability. Read more

Features Troubleshooting Concrete Cracking During Construction

Concrete has a natural tendency to crack because it's usually relatively weak in tension. When tension resulting from applied loads, restrained shrinkage, or temperature drops exceeds the strength of the concrete, a crack forms. Concrete can crack while plastic and after hardening. Cracking can be controlled during construction, however, by using quality materials, following proper construction practices, and using reinforcement and jointing. Read more

Problem Clinic Cutting Dowel Bars

Is it OK to shear steel rods when fabricating dowel bars for concrete slabs? Read more

Problem Clinic Sealers and Sealants

Can you explain the difference between a sealer and a sealant? Read more

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