November 1997 Table of Contents

Features Spotting Boom Pumps Safely

Before you unfold the boom of a pump truck on a new jobsite, be sure to check for power lines and other obstructions, excavations, and unstable ground. Read more

Features Nine Steps to Signing a Successful Contract

Contractors must take the time and effort to review every contract before signing it, being especially watchful for clauses that make it impossible for them to finish work on time, make a profit or win a contract dispute in court. Read more

Features Moisture Movement Through Concrete Slabs

Most manufacturers of floor coverings and adhesives recommend installing an impermeable covering on concrete floors only when moisture flow through the concrete is less than 3 lbs/1,000 sq ft/24 hrs. But problems with loose floor coverings and blistered coatings have increased in the last 10 years due to greater use of fast-track construction methods. Many owners want faster completion of their buildings, which shortens the drying time of concrete before coverings or coatings are applied. Read more

Features Six Ways to Increase Construction-Equipment Productivity

Productivity, or rather the lack of it, is the foremost problem confronting many construction firms. Contractors commonly measure their productivity by taking their output (measured in dollars or units) and dividing it by the number of labor hours required to achieve the output. But productivity is the efficiency by which materials are placed by labor and equipment. According to leading equipment manufacturers, contractors can expect to get 800 to 900 productive hours from a typical piece of equipment in a given year. Assuming a 2,080-hour work year (52 weeks, with a 40-hour work week) and 800 hours of productive equipment time, construction equipment is nonproductive 62% of the time. Read more

Features Public Art in Concrete

Since 1985, Seattle artist Vicki Scuri has worked to enhance the visual environment in urban and public spaces. Concrete has become a significant part of her work because she recognizes its durability, timeliness and cost-effective manufacturing techniques, under both factory-controlled and field conditions. Read more

Problem Clinic Bug Holes: How Big Is Too Big?

We've got a dispute on a poured wall placement regarding acceptable bug hole size. ACI 116R-90, Cement and Concrete Terminology, defines bug holes as small regular or irregular cavities usually not exceeding 15 mm (0.60 inch) in diameter. Read more

Problem Clinic Removing Chalkline Marks

We snapped a chalkline in the wrong place on a concrete driveway before sawing joints. Read more

Problem Clinic Effect of Overtime on Worker Productivity

To get a paving job done on time, we're planning to have our crews work six 10-hour days per week. However, I'm concerned about the cumulative effect of long hours on worker productivity. Is there any data on productivity and overtime specific to the cons Read more

Problem Clinic Chloride Content by Weight of Concrete

For corrosion protection, ACI 318-95, Building Code Requirements for Structural Concrete, specifies maximum water-soluble chloride ion in concrete as percent by weight of cement. What are acceptable levels when measuring chloride-ion content in existing c Read more

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