January 1989 Table of Contents

Features Floors That Pass the Test

F-numbers are used in specifications for floors. The FF number is an indicator of floor flatness or smoothness, while the FL number indicates floor levelness. The higher these numbers, the flatter or more level the floor. Read more

Features Future Bridge Deck Slab Construction

Every civilized jurisdiction, excepting Ontario, designs its concrete bridge slabs as elastic plates. Some model tests performed in Ontario show that an unreinforced bridge deck slab could carry as much as 80 percent of the maximum load of a comparable slab with normal reinforcement. Read more

Features The Fiscal Physical

Financial analysis is like a physical check-up for your finances. It lets you know how you're doing. With financial analysis, the telling points are the Balance Sheet and the Income Statement. Figuring out what they are telling you is done by analyzing financial ratios - mathematical relationships between different entries on the Balance Sheet and the Income Statement. Read more

Features A Proposed Method for Determining Compliance with Floor Thickness Specifications

Cores taken to reveal the strength of a slab on grade sometimes reveal another problem. They may reveal a core that is thinner than the specification. Questions then arise about whether the entire slab is out of spec, and if so, how thin it is. Read more

Features New Formwork Guide Issued

The American Concrete Institute (ACI) has issued revised recommendations for achieving quality, safety, and economy in forming and shoring operations. The new "Guide to Formwork for Concrete," prepared by ACI Committee 347, replaces a previous standard, ACI 347-78. Changes have been made in key areas to accommodate recent changes in concrete mixing and placing technology. Read more

Features Abseiling Speeds Exterior Building Inspection

Abseiling, a mountaineering technique also known as rappelling, is being used by many inspection firms and public works departments in Britain for building and bridge inspection, replacing conventional access by scaffolding and platforms. Read more

Features Laser-Guided Strikeoff Machine Helps Contractor Build Flat Floors Fast

Concrete contractor Dan Ahrens is sold on the machine that helped his crews easily place and finish 20,000 square feet of exceptionally flat concrete floor in one day. Read more

Problem Clinic Should Driveway Cracks Be Repaired?

My company does concrete sidewalk and driveway work. My crews put in joints that are deep enough and close enough together to control cracking, but occasionally we get a random crack. The owner always wants me to fix the crack. Is there any way to glue a Read more

Problem Clinic Placing Concrete on Frozen Subgrade

I've always been told never to pour concrete on frozen subgrade. Why is that a problem? Read more

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