September 1991 Table of Contents

Features Vaulted Concrete Roof Demands Custom-Built Forms

The challenging roof design of the Shiley Eye Center, University of California San Diego, required the use of custom-built formwork. The design of the 160-foot-long, 30-foot-wide roof called for arched joists having thickened center sections. The joists and beams also required an architectural finish because they are partially exposed. To meet these special requirements, the general contractor used custom-built wood-reinforced fiberglass forms. Read more

Features Developments in Shotcrete for Repairs and Rehabilitation

Many developments in shotcrete technology during the 1980s have enhanced shotcreting capabilities. Today, both dry- and wet-mix shotcretes often contain supplementary cementing materials, which improve shotcrete workability and performance. Read more

Features Ocean-Side Foundation Mat Pour Presents Challenges

A massive concrete foundation mat pour for a multiuse building complex in Newport Beach, California, presented contractors with a challenge. The mat, which varies from 3.5 to 8 feet thick, had to be placed over a quagmire 21 feet below sea level. To prepare the extremely wet site for concrete placement, workers first dewatered the area. After stabilizing the soil, they capped the area with a 4-inch-thick concrete water barrier topped with rolls of bentonite. Later, the bentonite was extended up the subgrade walls and coated with shotcrete Read more

Features Cement-Stabilized Alluvium Protects Embankments from Erosion

FNF Construction Inc. is using cement-stabilized alluvium (CSA) to channelize the Rio Salado's flow through Tempe, Arizona. By mixing portland cement, Class F fly ash, and native river bed (alluvial) soil, FNF is producing a CSA end product. While CSA is not new, using the extra-coarse alluvial deposits found in the Rio Salado bed is a new approach that offers increased durability and abrasion resistance. Read more

Features Concrete Canoe Racing

Concrete canoe racing is an opportunity for engineering students to learn about putting theory into practice, as well as how to work together as a project team. The idea for a concrete canoe race was spawned in 1970 when University of Illinois professor Clyde Kesler had his civil engineering honors students build a concrete canoe. Kesler invited the Purdue University civil engineering department chairman to have his students also build a canoe, then race it against the U of I craft. The first race was in May 1971 and was won by U of I. The next year Purdue hosted a race and won first place over 18 schools that responded to the area-wide invitation to participate. Read more

Features Grooved Bridge Decks Are Safer Bridge Decks

Unfortunately, far more highway bridges in the United States are "substandard" than are able to be repaired. A common sign of bridge deck wear is loss of skid resistance, which often becomes evident when water collects on the bridge deck. Bridge deck designers usually try to minimize water accumulation by establishing a cross slope with drainage channels and by deck surface texturing. A common method of texturing is transverse tining with a metal rake while concrete is still plastic. Although this method can produce grooves deep enough for a high-friction surface, the grooves are nonuniform and limited in depth. Read more

Features Daily Reports Repay the Effort to Keep Them Current

Concise, complete daily reports have many uses that more than repay the cost and effort involved in preparing them. The daily report provides an objective history of the entire project. It should be used as a tool for managing the current project and planning the next one. Data provided by well-prepared daily reports make the estimating and bidding process much more than an educated guess. Daily reports are also invaluable for documenting construction claims and showing what happened if problems should arise. Read more

Features Consolidating Concrete the Right Way

Properly using internal vibrators to consolidate concrete can help minimize honeycombing, pour lines, vibrator burns, excessive bugholes and other defects. This article sets forth the author's ten rules for using an internal vibrator correctly. Read more

Problem Clinic Quality Requirements for Curing Water

How pure does curing water for concrete have to be? We want to use river water to cure concrete for an elevated structural slab at a train station. Read more

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