Tuesday, August 16, 2011

[CI] 20110801

August 2011

Click on the cover image for the flip book version.
Decorative Makeover for Nashville’s Rocketown

The new building that houses Rocketown, a nonprofit youth facility, skatepark, and music venue, was transformed during workshops of the Concrete Decor Show & Spring Training in March 2011. Decorative concrete projects that were undertaken included a carved and stained vertical decorative installation, stenciling and coloring concrete slabs, and an outdoor water feature. Floors were polished during a Concrete Polishing Association of America certification training session.

The Silent Evolution: An Underwater Art Installation in Concrete

Fusing public art with environmental conservation, The Silent Evolution is located in the waters of the Mexican Caribbean. More than 400 life-sized concrete sculptures of people form a complex reef structure for marine life to colonize and inhabit. Casts for the sculptures were taken from a broad cross section of society. The sculptures were built with a pH-neutral concrete—a mixture of marine-grade cement, sand, and microsilica—reinforced with inert fiberglass reinforcing bars.

Impressionist Design in Concrete Wins Decorative Contest

Winning projects of Scofield’s Annual Decorative Concrete Awards

Decorative Concrete Celebrated by Awards Programs

The artistry and craftsmanship required to create an outstanding decorative concrete project were recognized by two recent awards programs:

Crushedwall Project for the Heartlands, Cornwall, UK

For the Heartlands, a development that is transforming a disused tin mine into a thriving cultural landscape and social enterprise, Walter Jack Studio was commissioned to work on a new retaining wall. To reflect the fluid state of concrete in the construction process, the formwork for the structure is being made from plywood and a long sheet of rubber that is crumpled and folded. A self-consolidating, architectural concrete mixture is being used.

Opportunities for Input on ACI Technical Document Content

There are several ways to influence the content of ACI standards, such as code requirements and specifications, and other ACI documents. The first opportunity is by becoming a voting member of document-producing committees. Others include participating in the Technical Activities Committee review process, making a public comment on a standard, or reporting errors and omissions. ACI members also have a chance to change documents by using the appeals process.

Changes to the ACI Building Code

A summary of key updates to ACI 318-11

Excessive Creep Deflections

Deflection data from 56 large bridge spans are presented. The plots show that deflections plotted against time in the logarithmic scale evolve systematically as a straight line. Also, the deflections of 33 of the 56 spans become excessive in less than 40 years, and the deflections of 20 of the 56 spans become excessive in only 25 years. The authors call for an improved creep model to allow for sustainable design of structures of high creep sensitivity.

Detailing Concrete Columns

Decisions made during the design of a reinforced concrete building can have major impacts on the project cost, schedule, change orders, number of requests for information, and overall constructibility. This Detailing Corner discusses various aspects of reinforced concrete column design and construction, including lap splicing of the longitudinal bars, placement of the column dowels, and offset bends.

Concrete Q & A: Limit on Slope of Field-Bent Reinforcing Bars

We placed some No. 6 vertical bars at a slight incline in the first lift of a wall placement. The protruding dowels are now too close to the wall forms for the next lift. When the horizontal bars are placed, we have little allowance for movement of the forms and we can’t meet the clear cover tolerance. The contract documents permit cold bending of No. 6 bars, and we have approval from the Structural Engineer. We planned to bend the verticals with a hickey bar, but the Inspector told us we couldn’t create a bar slope greater than 1 in 6 when doing this. I’ve never heard of this rule and can’t find it in any ACI documents.

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