December 1988 Table of Contents

Features Polyurethane Injection Stops Water Tunnel Leaking

A valve at the Pacheco Conduit inlet in California lets workers drain the conduit without draining the 5.3-mile-long tunnel that feeds it. Read more

Features Preheating Reinforcing Bars and Insert Plates

Before welding insert plates to reinforcing bars, preheating is sometimes needed to help reduce cracking at the welded joint. But preheating is costly and complicates the welding process. Read more

Features The Real Cost of Conservatism

Engineers are by nature a conservative lot. Buildings and bridges are designed to withstand loads from the expected and the unexpected. The same is not done when designing pavements: unexpected traffic volumes sabotage many designs. Read more

Problem Clinic Flake Calcium Chloride Added Directly to Concrete

What is wrong with putting flake calcium chloride in the concrete truck at the jobsite to offset cold weather effects on setting and strength gain? Read more

Problem Clinic Patching Board-Finished Concrete

Our company placed a poured concrete wall with a board finish. There are a few honeycombed areas that have to be patched. How can we make the patches as unnoticeable as possible? Read more

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