May 1982 Table of Contents

Features Calcium Aluminate Cement Concrete

Calcium aluminate (CA) cements are similar to the more familiar Portland cements in that they both require water for hydration, they both form concretes that set in about the same time, and they both require similar mix designs and placing techniques. Read more

Features Silica Fume

Silica fume, a by-product in the manufacture of ferrosilicon and also of silicon metal, is a very efficient pozzolanic material, though there are some problems associated with its use in concrete. Read more

Features Blast-Furnace Slag as a Mineral Admixture for Concrete

When slag, a by-product of the iron-making process, is quenched with water and rapidly chilled, it forms a glassy granulated material of sand-like consistency. Read more

Features Another Wrinkle in Steel Fiber Reinforcement for Concrete

Short, small-diameter steel fibers can improve the engineering properties of concrete notably flexural load-carrying ability, fatigue resistance and impact strength. Read more

Features Fly Ash in Concrete Part I

Fly ash is a by-product of the burning of pulverized coal in power plants. Read more

Features Fly Ash in Concrete Part II

The development of strength in fly ash concretes is closely related to the mix proportioning. Read more

Features How Super Are Superplasticizers?

Superplasticizers transform stiff, low-slump concrete into flowing, pourable, easily placed concrete. Read more

Problem Clinic Has Cement Been Stored Too Long?

We are storing and batching our own cement and aggregates and mixing our own concrete for a large job. Some portland cement has now been stored 5 months in the silos. There isn't any testing laboratory nearby and we wonder if there is a simple test to det Read more

Problem Clinic Flowing Concrete

Please explain flowing concrete. Is it the same as superplasticized concrete? If it flows so well, doesn't it segregate? Is it really as strong as concrete made with a lower slump? Read more

Problem Clinic Color Uniformity in Vertical Slipforming

We are slipforming some 80-foot-high lime silos for a sewage treatment plant and the sewage treatment authority wants the appearance of the concrete to blend with the nearby natural rock of the environment. We want to do this by painting but the owner ins Read more

Problem Clinic When All You Have Is Hot Cement

We have found that we will have to use some hot cement to place a concrete dome on a water storage tank. This cement will be shipped directly from the mill to the project and there will be little time for it to cool after it comes out of the grinding mill Read more

Problem Clinic Improving Sulfate Resistance

We must furnish concrete made with Type II cement having a tricalcium aluminate content of 4 to 5 percent. This is to be used in a floor that must be sulfate resistant. Would it make the floor more sulfate resistant to increase the concrete design strengt Read more

Problem Clinic Seawater for Mixing Perlite Concrete

A steel tank is to be built in a remote area to hold asphalt. A stable insulating base is needed and it is proposed to make this base of perlite concrete of 190 psi compressive strength. Can ocean water be used in the perlite concrete mix? The only altern Read more

Problem Clinic Lightweight Concrete Floor Over Plywood

We are building a 2-story condominium complex with concrete slab-on-grade. For the second story a foamed type of lightweight concrete is being used over plywood for sound absorption between floors. Please send us information regarding the proper chemical Read more

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