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Core Research

Established in 2000, the ICPI Foundation for Education & Research provides funding to address key research questions enabling manufacturers, designers and contractors to make, design, build and maintain better segmental concrete pavements. The updates to follow demonstrate a wide range of projects and studies the Foundation supports.

Landscape Architecture Foundation Performance Series Case Studies

The LA Foundation has assembled a tremendous collection of case studies documenting economic, environmental and social performance of specific projects and landscape systems. This information is important to an increasing number of practicing landscape architects who use performance metrics on various landscape systems for clients. One of those systems evaluated in various high-profile landscape architecture projects is segmental concrete pavements. An ICPI-curated collection of concrete paver projects published by the LA Foundation can be found at www.landscapeperformance.org/collections/segmental-pavement. Check this site in the coming months for a learning module on performance of segmental concrete paving. This presentation reviews tools to measure economic, environmental and societal performance benefits of segmental concrete paving.

Full-scale Load Testing of Paving Slabs and Planks

Modeled truckloads on slabs and planks will be validated with full-scale load testing.

An increasing number of companies are manufacturing, designing and installing paving slabs and planks. While these products can take a modest amount of vehicular traffic, a core question for the industry and designers is how much? To help answer this question, the ICPI Foundation funded finite-element computer modeling in 2015 that simulated truck tire loads on a range of paving slabs and planks on various bases and subgrade strengths. This resulted in draft structural design tables and procedures now under review by the ICPI Technical Committee for use by the industry and designers. To support this review, the Foundation funded validation of selected slab and plank shapes, base materials and thicknesses. Construction of a test area occurred at the end of June that will receive a significant number of heavy truckloads. With a start date later this summer, this full-scale load testing will likely take two years.

PICP Life Cycle Cost Analyses (LCCA), Tools and Training

This project includes developing an LCCA Excel tool that compares costs of permeable interlocking concrete pavement (PICP) to interlocking concrete pavement (ICP), as well as to conventional asphalt and concrete pavements. The tool is accompanied by a report that provides rationale on accounting for costs and benefits not directly related to PICP. Among several benefits, these can include land not used for detention ponds and reduced expenses to process stormwater and sanitary sewage from older combined sewer systems. When offsite savings are counted over decades, PICP can be less expensive than conventional pavements. Managed by Applied Research Associates, Inc., the project also includes a survey of selected PICP projects, conducting LCCAs and reporting on influencing costs and monetized benefits. Applied Research Associates will also conduct ICPI training sessions in the use of the LCCA tool.

Winter Operational and Maintenance Best Management Practices (BMPs) for Permeable Interlocking Concrete Pavers

The ICPI Foundation is leveraging about half a million dollars invested in PICP research conducted over the past few years by the Wisconsin DNR.

Construction of PICP test areas is anticipated in August 2017 at the Toronto and Region Conservation Authority in Vaughan, Ontario, Canada. Construction of the test area will be by ICPI member Ross Yantzi’s Pavestone Plus. This project evaluates the effectiveness of different cleaning equipment and winter deicer use compared to conventional pavement. Matching contributions from the ICPI Foundation and members will be from Canada’s Natural Sciences and Engineering Research Council. Oaks Concrete Products is donating permeable pavers and Lafarge is donating ready-mix concrete and aggregates for the PICP. The project will help address the primary PICP question: maintenance practices and cleaning equipment effectiveness. Results will amend ICPI Tech Spec 23 on PICP maintenance available on www.icpi.org.

Sidewalk Surface Smoothness Evaluation

Pathvu, Inc. (www.pathvu.com) will measure and determine the roughness index for 15 ICP and 15 PICP sites each in three cities. Sites have been identified in Pittsburgh, Philadelphia and Washington, D.C. Roughness data will be compared to roughness criteria from the U.S. Access Board originally developed by the University of Pittsburgh. Pathway roughness measurements are taken in anticipation of advisory material on wheelchair-pavement interaction being published by the U.S. Access Board in the next few years. The data should better position the industry by using the ASTM E3028 test method which will likely be referenced by the U.S. Access Board.

Wisconsin Department of Natural Resources

This grant supports two years of laboratory water quality analyses of outflows from a full-scale PICP no-infiltration design that has been previously monitored for several years, supported by ICPI members and Foundation contributors. The research fills the need for pollutant-reduction data on no-infiltration PICP designs. Located in a parking lot in Madison, WI, favorable pollutant reductions can qualify for credits mandated by the DNR. The industry is seeing wider use of no-infiltration PICP directly next to building foundations, over extremely weak subgrades and over high bedrock.

Road Map for Permeable Pavements

The ICPI Foundation, the National Ready Mixed Concrete Association and the National Asphalt Pavement Association collectively funded an invitation-only national conference November 14-15, 2017, organized by and located at the University of California at Davis. The deliverables will provide ways to overcome institutional barriers to wider acceptance of permeable pavements by stormwater agencies, municipal and state road departments and civil engineers.

Howard Road near Modesto, CA, will be systematically monitored for three years to determine how well it survives continuous truck traffic.

Interlocking Concrete Pavement Road Monitoring

This magzine’s Winter 2016 cover story reviewed mile-long Howard Road in Westley, CA. The unique aspect of this road is the heavy truck traffic. The ICPI Foundation funded three years of condition surveys per ASTM E2840, plus falling weight deflectometer testing to estimate its structural capacity and remaining life. The road’s owner, the Stanislaus County Public Works Department, will share the cost of the monitoring study to be conducted by Applied Research Associates, Inc. The outcome of this study will likely influence the use of ICP on other roads.

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Community Catalyst

Located a short boat ride from Peanut Island and the Palm Beach Inlet, the Riviera Beach Marina features 140,000 sf of interlocking concrete pavers, of which 105,000 sf are permeable. Winner of a 2016 Hardscape North America Honorable Mention Award, the $35 million Riviera Beach Marina redevelopment, completed in March 2016, concluded phase one of a multiphase revitalization project planned for the entire 26-acre Riviera Beach Marina District.

To attract the interest of private developers necessary for future phases of the revitalization master plan, the City of Riviera Beach and the Riviera Beach Community Redevelopment Agency (RBCRA) set their sights on the marina and the surrounding public land as the best site for phase one. The project was jointly funded with the City contributing one-third of the cost and RBCRA the rest.

“It was very important to the city council that this infrastructure investment project accomplish two things,” said Scott Evans, interim executive director of RBCRA. “Create a great waterfront public space for residents and visitors and attract future development from the private market.”


Photos courtesy of Coastal, an Oldcastle Company and Precise Paving, Inc.


PERMIT PROCUREMENT

Given the scope and scale of the Riviera Beach Marina District revitalization master plan, RBCRA had to apply for an Environmental Resource Permit (ERP) from the South Florida Water Management District. An ERP is required for development or construction activities to prevent flooding, protect the water quality of lakes and streams from stormwater pollution, and protect wetlands and other surface waters.

“Permeable [interlocking concrete] pavers were presented to us by the engineering design team as an environmentally positive method of construction,” said Mr. Evans. In addition to satisfying the ERP requirements for onsite stormwater capture and treatment, the permeable pavement was chosen for aesthetics, sustainability and lower cost.

“Using permeable concrete pavers in the parking lots and on the upper promenade was more cost effective than a traditional underground drainage system,” said Jill Lanigan, Director of Business Development at Song + Associates, the architectural design firm for the Riviera Beach Marina project.

“The soils in coastal municipalities are well suited for the use of permeable pavers,” said Patrick Figurella, P.E., Director of Engineering at Calvin, Giordano, and Associates. Based on the success his firm has had with other permeable paver projects in the region, Mr. Figurella said, “We are always looking for opportunities to use permeable pavers in other locations because of the advantages permeable systems afford with regard to reduction of runoff and providing water storage.”

The permeable paver system with standard exfiltration trenches allows the less than 14-acre marina site to provide 75% of the drainage for the entire Marina District, Mr. Figurella said. The Riviera Beach Marina site not only met the ERP’s present requirements, it established a sustainable site for future vertical development and related impervious surfaces.

In the interim, while RBCRA negotiates with a private developer for phase two construction, the public space created during phase one will be utilized for community programs to attract more visitors. Outdoor music festivals, a weekly green market and movies in the park are just a few of the events planned for the new space to serve the community and entice private developers to join the revitalization effort.

DESIGN AND CONSTRUCTION

Initial ocean-themed design concepts for the paver fields considered curvilinear patterns to emulate waves, but through several variations evolved toward an orthogonal design, explained Ms. Lanigan. The waves became geometric, with the varying widths of the fields and the varying lengths of the bands representing a stylized interpretation of waves rolling in and out from the shore. Ultimately, the final design responded better to the marina layout with an added benefit of streamlining the installation process, she said.

To reduce the heat island, the design team chose for the permeable paver fields lighter, natural colors, SRI>29 labelled Amaretto and Napoli. For the bands, they selected darker, contrasting slate to complement the other colors. With the large area of permeable pavers in the upper promenade and parking lots, the 25,000 sf lower promenade along the waterfront instead used standard 2 3/8 in. thick concrete pavers.

Except for 30,000 sf of roadway that was machine-installed, the majority of the pavers were hand installed, according to Rob Goossens, Vice President of Precise Paving. The standard paver section along the dock was installed first and was completed by December 2015. Construction delays compressed the paving schedule for the remaining portion of the project, but Precise Paving successfully installed 105,000 sf of permeable pavers in three months to meet the deadline.

“It was hectic, we had to double up our crews on this job,” Mr. Goossens said. “One good thing with permeable pavers, when you screed the No. 89 bedding aggregate, you don’t have to worry as much about rain causing bedding displacement as you do with regular sand-set pavers.” This allowed his first crew to be more aggressive, screeding up to 10,000 sf sections at a time while the second crew followed behind laying the pavers.


Video courtesy of Precise Paving, Inc.


DEADLINES AND DETAILS

The unique design of the upper promenade with variable field widths and darker bands between prevented machine installation and were installed by hand. For the permeable paver cross section, 14 in. of ASTM No. 4 stone was placed first, then 5 in. of No. 57 stone, followed by 2 in. of No. 89 stone for a total water storage depth of 19 in. beneath the 4 x 8 x 3 1/8 in. thick permeable pavers.

For the roadway, the only section of the project that could be machine installed, the paver manufacturer worked with Precise Paving to optimize mold configuration and determine the best way to palletize the product in order to achieve maximum speed and efficiency.

“Most of it went according to plan,” Mr. Goossens said. “The speed tables in the roadway were probably the biggest challenge.” The original design planned for the speed tables to be poured concrete, but Mr. Goossens convinced the design team to use permeable pavers instead, which saved time and cost by eliminating the concrete for these four 20-foot wide sections. This modification also maintained the continuity of the paver roadway from one end to the other. “It saved the project time, money, and at the end of the day, I think it’s a better product,” Mr. Goossens said.

“It’s not too difficult of a task, but you do have to account for the slopes and the elevations you need to hit,” Mr. Goossens said. “That starts of course with the base and also our screeding.” The elevation change of 6 in. brought the speed tables up flush with the curbs and pedestrian walkways from the parking lot to the event center so they could serve the dual purpose of being crosswalks as well. White pavers were used to demarcate the crosswalks and also for arrows on either side of the tables to alert drivers. Red stripes of ADA-compliant pavers were placed on both sides of each crosswalk.

“This was the first time we used permeable pavers in this manner and they worked beautifully,” said Mr. Figurella.

THE SUPERIOR OPTION

Permeable interlocking concrete pavements (PICP) have become more efficient from a structural and water management perspective. The biggest change agent advancing PICP toward greater use is their cost-effectiveness, especially for redevelopment projects such as the Riviera Beach Marina where every parcel is premium property. Sacrificing land to a detention pond or paying the high cost of installing underground storage vaults can’t compete with the volume and pollutant reduction efficiency, minimal maintenance, longevity, and aesthetic quality of PICP.

Another factor advancing growth is studies by various universities confirming PICP performance. Last but not least, mandates from the U.S. Environmental Protection Agency for onsite stormwater detention, treatment and infiltration make PICP a superior management option. From a life-cycle cost standpoint, the paver surface will last 40 to 50 years without replacement. In contrast, an asphalt surface cracks, requiring routine and unsightly patching, and eventual milling and repaving two or three times over 50 years.

REACTIONS AND RESULTS

Over a year has passed since phase one completion of the Riviera Beach Marina. “We’ve seen a large boost in the number of visitors, thousands of people,” Mr. Evans said. “And our waterfront businesses have had increased traffic as well.” Feedback from the community has been positive. “People really love the public spaces we’ve created.”

Despite initial trepidation by some, Mr. Evans said, concerns have been laid to rest on using permeable pavers for such a large area. “Performance has been positive and the system is working as designed. We’re extremely happy with it.”

Regarding maintenance, RBCRA has conducted occasional spot cleaning and sweeping, but hasn’t had any major issues, Mr. Evans said. “We’ve installed a few monument signs recently and there was concern that the process would be more challenging, but it went smoothly. We were able to take up the pavers, make some changes for the signs, and then put them back successfully.”

“It really turned out to be a great project,” Mr. Goossens said. “We had a demonstration there in June, brought in a fire truck and doused an area with 200 gallons per minute for 10 minutes. Walking over the area after they shut off the hose, there was no standing water and you could actually hear all the water filtering down through the aggregates. It’s impressive.”

“This marks the first time we’ve used permeable pavers for a city street,” Mr. Figurella said. “Riviera Beach is leading other municipalities to consider the utilization of permeable pavers for public roadways or alleyways.”

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Cooler than the Conventional

An estimated 3 to 4 million square feet of concrete grid paving units pave intermittently used parking lots, fire lanes, ditches, slopes, and boat ramps each year in the U.S. and Canada.

ICPI publishes a Tech Spec technical bulletin (No. 8, see www.icpi.org) on this product typically used to help reduce stormwater runoff while accommodating vehicles by reinforcing grass with concrete. Unlike plastic grids, concrete grids have an ASTM product standard, C1319-17 Standard Specification for Concrete Grid Paving Units. This standard defines a concrete grid and provides requirements for compressive strength, absorption and freeze-thaw durability.

Grids have maximum dimensions of 24 x 24 in. and a minimum thickness of 3 1/8 in. The percent solid recently has been updated in C1319 to range from 45% to 75%. This enables grids to conform to the minimum 50% unbound (non-solid) requirement in LEED version 4, Sustainable Sites. An Urban Heat Island Reduction credit is earned when an open-grid pavement system is used. This credit is included in LEED because grids can reduce microclimate temperatures by as much as 4° C compared to conventional pavements.

Grid pavements allow a cooler surface by combining the durability of concrete with grass.

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HNA 2017 Highlights

Contractor briefing session

Last October, contractors and dealers from across the U.S. and Canada attended HNA. This year, HNA will take place on Oct. 18–20, at the Kentucky Exposition Center in Louisville. Registration for HNA 2017 is already surging ahead of last year’s record crowd.

CONTRACTOR BRIEFING SESSIONS

Seven FREE Contractor Briefing Sessions will take place in the Trade Show Floor Classroom, including:

  • Five Ways to Future-Proof Your Hardscape Business
  • The Biz-Builder Blueprint for Contractors
  • OSHA’s New Crystalline Silica Regulation
  • ICPI Installer Certification, Advanced Designations, and Their Value
  • Opportunities for Permeable Pavers in Residential and Commercial Marketing

HARDSCAPE DEMONSTRATIONS IN THE HNA OUTDOOR ARENA

Nationally renowned instructor Bill Gardocki, owner of Interstate Landscape Co., Inc., will lead a live continuous two-day build that will highlight interlocking concrete pavement, SRW and permeable interlocking concrete installation best practices. The build will also include one-hour sessions on tools of the trade, hardscape lighting and outdoor kitchens.

EXHIBIT FLOOR

850 companies will exhibit indoors and out, including more than 170 hardscape exhibitors. The trade show floor will feature top paver manufacturers and leading suppliers of materials, equipment and services to the concrete paver industry. You will also gain access to the largest hands-on outdoor exhibit area through both HNA and the GIE+EXPO (Green Industry Equipment EXPO), included in your trade show admission.

HNA CONFERENCE SESSIONS

Conference sessions will provide attendees with a broad range of important education for their businesses, including:

  • Estimate Accurate Job Costs to Always Make a Profit
  • Emerging Online Lead Generation Trends for Residential Hardscape Businesses
  • Strategies to Win More Profitable Contracts and Overcome The Low Bid Process
  • Setting Up Your Hardscape Crews with the Right Technology to Increase Profits and Efficiency

DEALER ACTIVITIES

HNA Awards

The HNA Dealer Program, in its seventh year, is designed to help dealers accomplish two objectives: overcome the challenges in their market in order to grow their companies and identify what works and what doesn’t in a company’s unique market area—urban and rural. The program will feature Alan Beaulieu, one of the nation’s most informed economists examining the prevailing challenges confronting business. In addition, Dealer Day activities give dealers a one-of-a-kind networking opportunity and a first look at the trade show floor before it opens to everyone.

INSTALLER COURSES FOR CERTIFICATION AND DESIGNATION

Pre-show courses at the downtown Hyatt Regency Hotel in Louisville give HNA participants an opportunity to earn credentials to help differentiate themselves from their competitors. ICPI courses include the Concrete Paver Installer, Advanced Residential Paver Technician, Commercial Paver Technician and Permeable Interlocking Concrete Pavement Specialist. Three additional NCMA segmental retaining wall system installer courses are also offered.

HNA INSTALLER CHAMPIONSHIP

Installer championship

Twenty-four of the most talented installer teams will compete for the coveted championship. The competition will test and recognize the skill, dedication and passion of hardscape contractors from Canada, the U.S. and Mexico. The Grand Prize package is valued at over $10,000!

HNA AWARDS

Award-winning projects from throughout the U.S. and Canada will be on display and honored. The HNA Awards recognize outstanding hardscape projects by contractors building residential and commercial walkways, patios, driveways, commercial plazas, parking lots, streets and more. Project categories include concrete paver, clay paver, segmental retaining walls, combination of hardscape products and, brand new for 2017, the porcelain paver category.

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Success from Failures

Most progress in pavement design comes from failure. For accurate and predictable pavement design, pavements must be damaged and eventually rendered useless by repeated truck wheel loads to understand where that point lies. In fact, modern highway pavement design was originally based on load testing from trucks conducted by the American Association of State Highway Officials in the 1950s. The notion of an 18,000 lb (80 kN) equivalent single axle load as the basis for loading in pavement design emerged from these tests. Among many things, this testing discovered Miner’s Law, i.e., doubling wheel loads increases pavement damage to the fourth power. This exponential relationship between wheel loads and pavement damage is why truck owners pay high road use taxes—trucks do the most damage.

Since the 1950s, machines were invented that quickly apply truck wheel loads (or greater) without drivers. These large machines go by different names—accelerated load facility, heavy vehicle simulator, etc.—but all render 20 years of wheel loads in a matter of months. Often housed at universities or state departments of transportation, these machines have tested thousands of asphalt and concrete pavements. This research via load testing is the norm for conventional pavements. Testing, most of it funded by tax dollars, led to longer-lasting designs. Such research superbly uses tax resources because of the huge ROI: accelerated load testing costs millions; road networks cost billions.

For permeable interlocking concrete pavements (PICP), accelerated load testing validated ICPI design tables for subbase thicknesses published in 2011. Load testing was conducted in 2014 by the University of California Pavement Research Center in Davis (see picture). The design tables developed by the Center, with help from mechanistic modeling, provide for slightly thinner bases in some situations than those in the ICPI design tables. Accelerated load testing doesn’t come cheap: the testing at Davis cost about $400,000, co-funded by the ICPI Foundation, California paver manufacturers and the Cement Association of California and Nevada.

Institutionalization from this industry investment include Caltrans PICP design tables in their pervious pavement literature, and in the ASCE national PICP standard to be released later this year. While the testing certainly confirmed that heavy trucks can repeatedly traverse PICP, additional accelerated load testing is needed using stronger subbases, thereby expanding PICP use to busy urban streets (while storing and infiltrating stormwater).

While there has been accelerated load testing (mostly in the 1980s) of interlocking concrete pavements (ICP) here and overseas, they have taken mostly an experiential, empirical path toward validation of their structural capacity. Validation has come from millions of square feet used in airfield and port applications withstanding wheel loads as much as 10 times greater than trucks. For road applications, some of the busiest downtowns have seen repeated bus and truck traffic. Downtown North Bay, Ontario, and San Antonio, Texas, are examples. Built in 1983, North Bay is likely approaching 4 million standard axle loads and San Antonio around 3 million, built in 1986.

While experience is informative, the interlocking concrete pavement industry might consider systematic full-scale load testing to undergird current structural design methods. A multimillion dollar investment will put ICP in the same testing league that refined conventional asphalt and concrete pavements over the past several decades. ICP accelerated load testing will instill immeasurable confidence in designers, boost the industry’s technical credibility, and help lead to institutionalization by government road agencies and civil engineers. Like the PICP load testing, funds for ICP load testing will likely come from industry and not tax dollars, since there aren’t yet hundreds of miles of ICP roadways owned by municipal or state transportation agencies.

Success in expanding ICP road applications will come from taking ICP to the point of failure via accelerated load testing. Testing to failure is the sine qua non of pavement research and design. This can add further fuel to justifying lower life-cycle costs from investing in ICP.