Lastest CTT Hot Off the Press (Vol. 26, No. 2, August 2005)

Concrete Technology Today is a PCA newsletter for architects, concrete producers, engineers, and concrete technologists. Articles include:

• Concrete in the Marine Environment—Treat Island Marine Exposure Station
• Air-Void Clustering: A Rare Problem Explained
• Concrete Permeability—Revisiting T.C. Powers

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Located on the Bay of Fundy near Eastport, Maine, the Treat Island exposure station was established by the US Army Corps of Engineers (USACE) in 1936 to study concrete durability in long-term programs. The exposure site inherently imposes a unique combination of natural severe environmental conditions ideally representative of severe field exposure conditions.

Under the heading of “Improved Durability of Concrete,” the field exposure studies at Treat Island have provided data useful in determining concrete’s resistance to frost attack, alkali-aggregate reaction, sulfate attack, and corrosion of steel with variable cementitious types and contents, aggregate types, chemical admixtures, and water-cementitous ratios. More.

Long-Term Performance of Plain and Reinforced Concrete in Seawater Environments

This 18-page report addresses the long-term exposure and durability of various types of concrete exposed to seawater on the California coast.
RD119—$25

This report is also found on PCA's Concrete Technical Support Library (CD019 and DVD019).

Pinto Concrete—Is there a cure?

Q: We had a concrete walkway put in a week ago and there are still a lot of dark areas as well as water stain-like markings. Is this normal? Should we be wetting it down and if so, how often?

A: It is not uncommon for concrete to have some mottling at an early age. Typically, it is advisable to treat the concrete with a series of wet and dry cycles (with warm or hot water if possible) to help stabilize the color. A helpful reference for further reading would be an article from PCA’s Concrete Technology Today newsletter called "Pinto Concrete: Is There a Cure?" which you may access here.

There is a more comprehensive discussion of discoloration issues in PCA publication Concrete Slab Surface Defects: Causes, Prevention, Repair (IS177).

Click here for more Concrete FAQs.

This research study compares results from accelerated mortar bar tests (ASTM C 1567) of reactive aggregate-SCM combinations with the performance of the same combination of materials in concrete structures, field-exposed concrete blocks, and laboratory expansion tests on concrete prisms (ASTM C 1293). More.

Effect of Cement Fineness and C₃S Content on Properties of Concrete, SN2871

This literature review, conducted by 3 industry experts from the University of Toronto and the University of Florida, is intended to provide guidance on the practical effects of changes in fineness and C₃S content on the heat of hydration and cracking potential of concrete. More.

SCMs for Use in Concrete Comes to Seattle
October 6, 2005, Seattle, Wash.

Explore the use of supplementary cementing materials (SCMs) and their impact on the durability, workability, economy, and sustainability of concrete. More.

Concrete Cracking Workshop
August 18-19, 2005, Northwestern University, Evanston, Ill.

Focus of this workshop is the newer research on materials and structural design. It is hoped that by melding these views new directions will be found to produce concrete with a 100-year service life. Click here for more information.

For a complete listing of conferences, click here.