In this issue ... Streets & Local Roads
New Award Recognizes Outstanding Municipal Pavements
Optimize Street Designs
National Center Launch Signals New Dimension in Research, Technology Transfer
Urban Public Works Program a Source for Durable Design Standards
Literature Addresses Alkali-Silica Reactivity Acceleration
ACPA Invites Officials to Transportation Reception

The American Concrete Pavement Association (ACPA) has created a new group of awards to recognize the role of concrete pavements in downtown development in the United States.

The new Main Street USA awards will recognize projects in which concrete pavement was a key component in the increasingly popular development or redevelopment of downtown areas.

The award specifically cites technological enhancements, efficiency improvements, or exemplary service to an agency, contractor, or the concrete pavement industry at large.

With ACPA's release of the new StreetPave software design tool, engineers are able to reduce overall pavement thickness. Recommendations that may be used to increase the pavement's ability to carry heavier traffic loads are depicted in table 1. These new load transfer recommendations are based predominantly on the Average Daily Truck Traffic (ADTT), whereas previous recommendations were based solely on pavement thickness.

Whenever the volume of daily truck traffic exceeds 80 trucks per day, the use of dowels to increase load transfer efficiency should be considered. However, in some cases, this may be with pavement thicknesses in the range of 6 to 6.5 in.

In these cases, using a stabilized subgrade or a granular subbase may instead be used to reduce the potential for subgrade pumping resulting in pavement roughness. Past pavement performance and engineering judgment should be considered in selecting a load transfer mechanism.

100

6.5 in.

Improved subgrade/subbase support or 1" dowels

The addition of dowels will greatly improve the load transfer efficiencies (LTE %) of the pavement by improving the ability of adjacent slabs to share the traffic load.

The primary mechanisms for load transfer are aggregate interlock (LTE of 30-80%), stabilized subbases (LTE of 50-90%), and dowel bars (LTE of 80-95%).

Doweled pavements have been shown to increase LTE 2 to 3 times that of pavement using aggregate interlock or stabilized subbases.

The load transfer performance will depend on the selected materials and the quality of construction within a given project.

When granular subbases are specified, they function not so much as a structural layer, but as a non-pumping layer to reduce the soil erosion under the pavement slab.

Since low-volume roads typically do not fail by erosion, they do not require subbases to prevent the subgrade pumping. In most cases, street and road concrete pavements for low-volume roads can be placed directly on the compacted subgrade.

For most street and local road applications, traffic levels may never achieve the volumes necessary to induce faulting and pumping. Most streets and roads are designed to carry 250,000 to 2 million equivalent single axle loads (ESALS) during a 30-year design life.

The critical concern is when average faulting on a stretch of pavement reaches 0.10 in or greater. At this average condition, the pavement becomes uncomfortable and typically triggers concrete pavement rehabilitation.

Questions? Contact Scott Haislip at 847-966-2272.

The National Concrete Pavement Technology Center (CP Tech Center) commemorated its official launch recently with a signing ceremony and Board meeting.

ACPA has been a driving force in the development of the CP Tech Center, the concept for which emerged earlier this year.

The idea was to unite the concrete pavement research and technology transfer

and implementation by establishing a national center that would draw together the researchcommunity and facilitate projects.

After careful consideration, ACPA's Executive Committee and Board of Directors agreed to help establish the national center.

A decision was made to evolve the center from the former Center for Portland Cement Concrete Pavement Technology at Iowa State University.

"In less than nine months, we've gone from Iowa State to what we are now, a center advancing a coordinated program of research, technology transfer, and technical implementation," said Tom Cackler, P.E., Director, CP Tech Center. "We're ready to roll up our sleeves and get started devoting products and energy to the priorities of our stakeholders."

Growing the regional center to a national organization required the cooperation of many key stakeholders at both the national and state level (notably, the Iowa Department of Transportation, as well as members and staff of the Iowa Concrete Paving Association). Equally important, the CP Tech Center came to be because of the confluence of a series of events.

One such event was the creation of the Concrete Pavement Strategic Roadmap, or CP Roadmap, a comprehensive national research plan to be cooperatively focused through 12 specific tracks, as well as a process for managing it. Another event was the passage of SAFETEA-LU, which provides $16.4 million in funding for concrete pavement research, as well as a special provision of $10 million for specific research and technology projects to be administered through the CP Tech Center.

While this funding is available for research and technology transfer, the core administrative will be funded separately. ACPA and other key stakeholders are supporting the CP Tech Center's administrative core function by pursuing alternative funding streams.

The latest issue of ACPA's R&T Update addresses surface deterioration caused by alkali-silica reaction (ASR) acceleration by potassium acetate deicers.

The issue also details an interim procedure developed by the Innovative Pavement Research Foundation (IPRF) and Federal Aviation Administration (FAA) to screen and mitigate ASR by airfield pavement deicers for new concrete pavement construction.

ACPA's work in this area, including the R&T UPDATE, were prompted by the FAA, which sought a solution to the problem.

The agency plans to publish ACPA's report in an FAA engineering brief.

Guntert & Zimmerman designed the double telescopic S850 QUADRA Slipform Paver for paving widths 12' to 34' (3.65m - 10.36m) on both urban and residential paving projects without sacrificing weight, power, and balance necessary for producing quality airport and highway concrete pavements..

The S850 paver features:
• narrow profile design for work among obstacles and confined spaces;
• reduced heat and noise exposure for the paver operator; and
• structural integrity for withstanding frequent width change, transport, and to insure quality riding pavements.

For markets where width changes are not a common occurrence, G&Z also offers the S850(ST) Single Telescopic Tractor Frame.

Standard features of the S850(ST) include:
• telescopic hose/electrical trays from 12' - 34' (3.67m - 10.34m);
• no large crane or disconnection of hoses required for Tractor Frame width changes; a mechanic's truck crane or boom truck is sufficient; and
• the same standard features as the S850 Double Telescopic Paver except for the tractor frame.

Both the S850 and S850(ST) are available with optional kits that include additional features. Contact Jan Miller at 1-800-733-2912 for more information on these versatile pavers.

As cities and towns increasingly work to bring business and residents closer to cities, local agencies now face the challenge of developing downtown streets and local roads that are aesthetically pleasing, yet stand the test of time.

Decorative concrete is a great way to add beauty to and streets and locals roads projects, while maintaining the safety and long-term performance of concrete pavements.

Local federal officials have chosen different forms of decorative concrete for a range of applications, including crosswalks and sidewalks.

Federal officials, and transportation industry representatives and other stakeholders met for the first time November 8-10 at the Mid-Atlantic Green Highways Forum to discuss how transportation development can be pursued while considering environmental sustainability through the Green Highways Initiative.

ACPA has been involved with the initiative since its inception and continued its participation during the forum this week by acting on the Executive Plenary Panel and in discussions on creating a "roadmap" to guide future activity.

The Forum represented one of the first opportunities for industry representatives to sit down with Federal Highway Administration, State Highway Agencies and Environmental Protection agency officials and work together on creating sustainable practices in developing the U.S. transportation system.

More than 300 industry participants joined the forum in College Park, Md., for concurrent sessions and presentations on research and technology on sustainable transportation practices.

ACPA represented the North American Concrete Alliance at the Forum.

"Based upon productive discussions and exchanges, the thrust of the program ended up focusing on how we can meet our transportation infrastructure needs while being sensitive to our environment, so that both are better than before," said Robb Jolly, ACPA Senior Vice President of Market Development.

Keynote speakers at the forum included EPA Administrator Stephen L. Johnson and EPA Region III Administrator Donald Welsh, and participants included the U.S. Army Corps of Engineers; state highway organizations; fish, wildlife, and park services; engineering consulting firms; contractors; academia; recycled products manufacturers; and suppliers of supplementary cementitious materials.

ACPA Concrete Pavement Progress is published 12 times per year and covers current practices and case histories in the concrete pavement industry. ACPA Concrete Pavement Progress is distributed free of charge to public officials, ACPA members, executive committee, board of directors, and affiliated chapter/state paving associations.

All rights reserved. Copyright 2005 by the American Concrete Pavement Association. No portion of this publication may be reproduced mechanically or electronically without the expressed written permission of the American Concrete Pavement Association.