Cement-Modified Soil Solves Kentucky Airport Problem

During the design of a 2,800-foot partial parallel taxiway, the Muhlenberg County Airport located in Greenville, Ky., discovered that the soils to support the one to three foot taxiway embankment were weak and would create issues with stability.

One method for dealing with unstable soil conditions in embankment construction is to place select aggregate fill onto a geotextile fabric in an effort to spread the load and “bridge” the unstable soils. Material and labor costs can cause this system to be quite expensive. In addition, the use of virgin aggregates is not the most efficient and environmentally sound use of natural resources. On the other hand, in-place cement modification of unstable soils can provide a quick, cost effective and eco-friendly solution.

After reviewing options, the design firm of Garver, LLC decided to use cement modification as a means to provide a solid foundation for the embankment construction. Initial estimates indicated a significant cost and construction time savings using CMS, since modification would replace 9,000 tons of aggregate and associated geotextile fabric. From a sustainability standpoint, it would have taken approximately 360 truck trips to deliver the aggregate needed compared to 25 truckloads of portland cement.

Mt. Carmel Stabilization Group performed the cement modification. The design called for 6 percent cement content mixed to a depth of 16 inches with a seven-day cure before embankment construction proceeded. Modification was completed in two days during June 2008 and embankment construction began one week later. When the final costs were tabulated, the CMS process saved 50 percent compared to the geotextile fabric and aggregate alternative.

Save Money and Resources with Cement-Stabilized Bases and Subgrades

Cement-stabilized bases and subgrades have been used for many years to provide improved pavement performance with a substantial cost savings. Also, stabilizing in-situ materials with portland cement conserves natural resources. Virtually all recycled pavement materials and most soils can be stabilized in this manner.

PCA will present a one-hour webinar on cement-stabilized bases, August 13, 10-11 am CDT. The session (PDH credit available) will cover cement-stabilized base and subgrade applications, benefits, mix design, construction, and QC/QA. The cement-modification of soils will also be discussed. The cost is $60 ($30 for PCA members; government officials; students and educators).
More information and purchase

Webinar Registration Now Open

PCA is well known for providing the highest quality of education in concrete technology and will now make some its most popular topics available via webinar.  The webinars are an excellent way to provide employees with the latest information while minimizing the time spent away from the job.

The courses listed below are now open for registration. All the sessions are held 12-1 pm CDT at a cost of $35.
> Chemical Admixtures for Use in Concrete - August 27
> Top 10 Myths in Concrete Construction - September 3
> Decorative Concrete - Finishing with Color and Texture - September 9
> Supplementary Cementitious Materials for Use in Concrete - September 15
> Impact of Cement Characteristics on Properties of Concrete - September 29
> Pervious Concrete - October 8
> Volume Changes of Concrete - October 15

Don't Miss the 2010 Concrete Bridge Conference

The National Concrete Bridge Council has opened registration for the 2010 Concrete Bridge Conference to be held February 24-26, at the Hyatt Regency in Phoenix, Ariz.

The theme of this year’s Conference is “Achieving Safe, Smart, and Sustainable Bridges” and will include many technical sessions, a tour of local bridges, a reception featuring the presentation of the 2010 Concrete Bridge Awards, and an exhibit area. The conference will have five focus areas: Sustainable Bridges, Smart Bridges, Non-Destructive Evaluations of Bridges, Durable Bridge Decks, and Innovative Design and Construction.
Exhibitors and attendees can register at www.nationalconcretebridge.org
Contact Sue Lane

Structures Professors Get a Lesson in Concrete

Eighteen civil, architectural, and construction engineering professors from U.S. universities met at PCA's Skokie, Ill., offices for the 18th Annual Building Professors’ Seminar, August 3-5. Topics included teaching the fundamentals of structural concrete design, models and aids for teaching reinforced and prestressed concrete design, economic aspects of design and construction, concrete solutions for sustainable development, changes introduced in ACI 318-08, and seismic design and detailing for concrete buildings. Forums and open discussions enabled participants to compare notes on successful teaching of reinforced concrete building design.

In addition, 21 structural engineering faculty attended the 11th Annual Bridge Professors’ Seminar, August 6-7. The purpose of the seminar was to provide professors with background information and tools to facilitate teaching new concepts introduced in the bridge design specifications. The focus was on the latest AASHTO bridge design specifications, which contain design requirements significantly different than those of the ACI 318 Building Code.

Regional promotion groups, Concrete Reinforcing Steel Institute chapters, and precasters sponsored the professors.
Contact Basile Rabbat

GreenSite Awards 2009 Entry Submission Now Open

Sustainable building practices are gaining acceptance in the competitive world of concrete construction. The editors of Concrete Construction and The Concrete Producer created GreenSite Awards 2009 to recognize the concrete community's innovative contributions to green building. Ten project categories will be honored as well as an overall GreenSite Project of the Year.

Any project participant, including architects, designers, contractors, and materials suppliers, may submit projects completed before January 1, 2009.
GreenSite projects can fall within any of 11 different categories:
> Commercial
> Residential
> Multi-family housing
> Landscaping
> Industrial
> High-rise
> Institutional
> Repair and rehabilitation
> Retrofitting
> Historic restoration
> Transportation

The entry deadline is August 14, 2009. 

Winning projects will be featured in the November issues of Concrete Construction and The Concrete Producer and on the publications' Web sites.  GreenSite winners will also receive special recognition at the GREENSITE exhibit at World of Concrete.
More information at www.concreteproducer.com