September 1982 Table of Contents

Features Choosing a Concrete Vibrator

Today most concrete is consolidated by vibration. Vibration subjects the fresh concrete to very rapid impulses which temporarily liquefy the mixture and cause the concrete level to subside. Read more

Features Vibration of Superplasticized Concrete in Tunnel Forms

A Swedish study embraced preliminary tests at the form manufacturer's factory and full-scale tests in connection with the production of concrete structures for 13 one-family houses. Read more

Features Climbing Tower Crane and Extended-Life Superplasticizer Solve Difficult Placement Problems

New York's Trump Tower, a 58-story, 644-foot-high multiuse building is an all-concrete structure with an unusual structural design. Read more

Features The Value of the Vibratory Screed

Concrete with low water content and stiff consistency is desirable for slab and pavement work, but such mixes develop their full durability and strength only when properly compacted. Read more

Features Concrete Takes a Helicopter Ride

It took nine days for pack mules to climb the nearly 6000 feet that separate Palm Springs, California and the top of Mt. San Jacinto, where foundations were bing built for towers to support a tramway which takes people up the mountain. Read more

Features Floor Surface Leveler Said to Produce Flatter Surfaces

Specifiers today are becoming more and more exacting as to the flatness of concrete floors. Read more

Features Should the Pumping Contractor Know More About Mix Design?

The general contractor usually needs many subcontractors to complete his project and it is impossible for him to be an expert in each trade. Read more

Features Field Supervision: an Important Part of Construction Safety

Field supervision is the owner's and the designer's last line of defense. Read more

Features What Is Roller Compacted Concrete?

In the construction of mass concrete structures such as dams and foundations also feasible for the rapid placement of highways and runways specially-proportioned no-slump concrete can be transported, placed and compacted using regular earth-moving and rock-fill construction equipment. Read more

Features What Makes a Good Power Trowel?

The power trowel also referred to as a troweling or finishing machine is used in the smoothing and finishing of concrete slab work. Read more

Features What Is the Best Way to Transport Concrete?

The best method for the transportation and distribution of concrete can be selected after considering the following: Conditions of the jobsite (location of trees and adjacent buildings, effect of noise on neighbors, land contours, and the need for all-weather access); availability of equipment; continuity of concreting; season of construction (hot/cold weather requirements); temporary improvements which may be required for work to proceed; maintaining uniformity; and concrete specification. Read more

Features Utah Dam Faces Slipformed

Upper Stillwater Dam near Bonneville, Utah, will be the first dam in the United States to be constructed with a combination of such unconventional materials and techniques as: slipformed fly ash concrete facings made with slipform paving equipment, and a roller compacted concrete base slab. Read more

Problem Clinic Black Concrete Driveways

A job calls for 200 cubic yards of black concrete for driveways. We have been told that this would require 10 percent black pigment by weight of cement. If we use lampblack as pigment will it knock out the entrained air? What can we do to be sure the job Read more

Problem Clinic Deicers on Parking Garage Decks

Do you advocate that parking garage decks be designed to protect against deicer attack even if they are enclosed? Is there enough dripping of salt water off of parked cars to cause trouble? Read more

Problem Clinic Site Access:

Do you have any tips on how to bring an excavating crane onto a site where the access is narrow and where it is important not to do anything that might antagonize the owner of the neighboring property? Read more

Problem Clinic Cracking at Columns in Outdoor Flatwork

Why do we see so many cracks in flatwork around small columns? The problem seems epidemic in shopping centers. For example, this picture was taken in a shopping center where the quality of the concrete was generally good except at columns. Unfortunately, Read more

Problem Clinic Call in an Expert

The vertical edges of a number of exterior columns of one of our apartment buildings are breaking away, leaving reinforcing steel exposed, and this steel is corroding. Read more

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