May 1984 Table of Contents

Features Earthquakes and Reinforced Concrete

Seismic buildings codes usually specify lateral design forces in a formula that involves the seismicity of the region; the importance of the occupancy; the type, period, and weight of the structure; and sometimes the soil properties of the site. Read more

Features How to Cope with High Concrete Temperatures

Sooner or later each summer, some contractors will be in for a surprise. Their concrete will be acting in ways they didn't expect, losing slump rapidly and setting too fast. On top of that the strength may be low. Experienced contractors prepare ahead of time to avoid these unexpected but unnecessary troubles. Read more

Features New Look in Tilt-Up

When the developers for a specialty shopping center in Florida met with the design/construct firm, one design concept had already been determined: the mall would feature an architectural style reminiscent of early nineteenth century Charleston and Savannah. Read more

Features Precast Leave-in-Place Screed Rails for Floor Construction

The use of edge forms or hard screeds is essential in building flat floors. Precast concrete screed rails for this use in floor construction have recently been introduced in the United States. The rails remain in place after concrete placement and become a permanent part of the floor. Read more

Features Sealers or Overlays?

If your problem is protecting rebars by keeping deicing salts or wind-borne or water-borne sea salts out of concrete, don't select a sealer without considering the use of a concrete overlay. And just as important--don't select an overlay until you've thought seriously about using a sealer. Read more

Problem Clinic Bulging Block Wall Belowgrade

One wall of our block basement is bulging inward and it has cracked horizontally for the length of the wall. We don't have any accurate measurements, but we think it has moved inward at the center about an inch during the past week. The wall is about 25 f Read more

Problem Clinic Protecting Cut Ends of Epoxy-Coated Bars

After epoxy-coated bars are sheared isn't it desirable or necessary to provide some kind of protection for the newly exposed ends? If so, can this be done on the job? Read more

Problem Clinic Saving Cows

I lost an expensive cow when she slipped on manure on the dairy barn floor and couldn't get up. Is there a sure-fire way to make the floor safe for cows? Read more

Problem Clinic False Set

Explain to me again what you mean by false set. Is it the same as flash set? Read more

Problem Clinic Mix Proportions for the Concrete You Buy

If I specify strength, air content, and slump when I order concrete, is the ready-mixed concrete supplier obligated in any way to tell me the mix proportions? I haven't been getting this information, and though I don't absolutely have to know what materia Read more

Problem Clinic Highway Straightedge

What's a highway straightedge? Is there anything to the claims that it makes floors less wavy? If so, does it increase the labor cost? Read more

Problem Clinic Shiny Residential Floor

We are under contract to build a large custom home. The buyers want to have concrete floors kept uncovered and with a shiny finish. We have never done this before and are seeking information for varnishing the slab. Read more

Problem Clinic Misfit Precast Panels

The vertical distances between attachments of our precast exterior wall panels aren't matching those of the high-rise building for which the panels were made. A careful check shows that the spacings on the panels match the drawings, but those on the build Read more

Problem Clinic A Safer Practice

In high-rise construction we never remove our shores until we're satisfied by tests that the floor has achieved sufficient strength. In recent years we've switched from cylinder tests to cast-in-place cylinders that are removed from the floor at the time Read more

Problem Clinic Prestress Loss

What do people mean by "loss of prestress"? Does this mean that the prestressing force is all going to be lost eventually, and if so, how long can you expect prestressed concrete to last, or to be safe? Or does it mean prestressed concrete isn't really de Read more

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