ICPI Foundation for Education & Research
Fall – 2017
Landscape Architecture Foundation Performance Series Case Studies ($75,000) – This project includes curation of case studies on performance of projects using ICP and PICP. This was completed last year. See https://landscapeperformance.org/collections/segmental-pavement for an ICPI-curated collection of concrete paver projects published by the LA Foundation. ICPI has developed the next deliverable, a learning module on performance of segmental concrete paving. This presentation includes tools to measure economic, environmental, and social benefits of segmental concrete paving. This information is important to an increasing number of practicing landscape architects who use performance metrics on various landscape systems for clients. The presentation will be posted on the Landscape Performance website in the coming months.
Full-scale Load Testing of Paving Slabs and Planks ($35,000 budget plus paving slabs and planks donated by ICPI members) – This is partial validation of selected slab and plank shapes, base materials and thicknesses developed by previous finite element modeling funded by the ICPI Foundation. Construction of a test area to load test slabs and planks is completed and we are awaiting the arrival of donated planks and slabs at Nicolock’s manufacturing facility in Frederick, MD. Donated paving units are from Oaks Concrete Products and Pavestone, and likely Armtec. Trucks loaded with pavers will make many passes over the pavements until they crack. We expect load testing to start in November. “Full-scale” load testing will likely take two years.
PICP Life Cycle Cost Analyses (LCCA), Tools and Training ($85,955 Applied Research Associates, Inc.) – This is a survey of PICP LCCAs, influencing factors, and monetization of PICP lifetime benefits, as well as development of an Excel tool for calculating LCCAs, training materials for ICPI member sales force, and a training workshop. Rather than develop case studies first, an LCCA Excel tool which compares costs of PICP to ICP, asphalt and concrete pavements has been delivered. This is accompanied by a report that provides rationale on accounting for costs not directly related to the PICP. Among several factors, the LCCA accounts for land not used for detention and reduced expenses to process stormwater and sanitary sewage from older combined sewer systems. Developing the report and Excel tool first enables LCCAs of various PICP case studies. A list of potential PICP projects for LCCA has been provided for review. These will be converted to case studies with training materials for ICPI commercial sales representatives by the end of 2107.
Winter Operational and Maintenance Best Management Practices (BMPs) for Permeable Interlocking Concrete Pavers (Cdn $105,500 - University of Toronto) – Construction of the PICP test areas is completed at the Toronto and Region Conservation Authority in Vaughan, Ontario. Construction of the test area was by ICPI member Ross Yantzi’s Pavestone Plus. Oaks Concrete Products donated permeable pavers and Lafarge donated ready-mix concrete and aggregates for the PICP. This project evaluates the effectiveness of different cleaning equipment and winter deicer use compared to conventional pavement. The next step is working with the principal investigator, Professor Jennifer Drake, to identify companies with cleaning equipment.
Sidewalk Surface Smoothness Evaluation ($22,000 Pathvu) – Pathvu has begun measuring the roughness of 15 ICP and 15 PICP sites in each of three cities. It will compare the results to US Access Board proposed guidance. Test sites have been identified in Washington, DC, Pittsburgh and Philadelphia and work has begun in Pittsburgh. This project should be concluded by the end of 2017. The roughness data will be compared to roughness criteria from the U.S. Access Board by the University of Pittsburgh. This work is being done 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 be better position the industry by using the same ASTM test methods referenced by the U.S. Access Board.
Wisconsin Department of Natural Resources – The Foundation funded a proposal at $79,918 to provide two-year support 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. Monitoring has begun and we anticipate receiving a report later in 2018. On behalf of the Foundation, ICPI members Bob Roehrig and Jennifer Schaff attended the Wisconsin Natural Resources Board meeting in April where the Board accepted the Foundation’s donation. A donation plaque was presented to the Foundation Trustees by Jennifer Schaff at the Foundation’s summer meeting in Toronto.
Road Map for Permeable Pavements, UC Davis – The Foundation funded $15,000 in support of an invitation-only national conference November 14-15, 2017 for a range of stakeholders to develop a road map for permeable pavements. The deliverables will provide ways to overcome institutional barriers to wider acceptance. The NRCMA committed $15,000 towards this conference as well as $10,000 from NAPA. Staff has worked with California members in developing an invitation list, as well as invitees from the U.S. and Canada. To date, 28 persons have committed to attending and approximately another 30 persons indicated that they will likely attend. Deliverables from this brainstorming session will be plan to address technical and institutional issues.
ICP Road Project Monitoring – The Foundation funded this proposal for $10,000 to ARA, Inc. for a three-years of condition surveys and falling weight deflectometer testing of a Howard Road. This road is 1-mile long, truck-intensive stretch in Westley, CA. The Stanislaus County Public Works Department will contribute an additional $10,000. The ICPI Foundation is applying to be a vendor of Stanislaus County. Once that is established, the County will issue a purchase order. The Foundation in turn will engage ARA to conduct a condition study. Non-destructive structural testing using a falling weight deflectometer will be conducted during the wet season. The timing of this project is important as the County is considering the use of 3.5 million sf of concrete pavers for roads in an industrial park. Construction is anticipated in 2019-20. The outcome of this study will likely influence the use of concrete pavers on these roads.
Municipal Interlocking Concrete Pavement Performance Modeling – This project consists of two contracts, one for $108,700 to Applied Research Associates, Inc. and another for $22,000 to Pavement Technical Solutions, Inc. Both consultants will model the impacts of interlocking concrete pavement (ICP) within municipal pavement management systems. This is done with to determine total life performance costs under various maintenance cost scenarios, and comparing them to that for asphalt and concrete. This will indicate if there is a compelling life-cycle cost case for municipalities to switch from asphalt or concrete pavements to ICP. The municipal pavement management systems examined will include networks and typical pavement sections from low or medium volume streets in Nashville, Tennessee, Boston, Massachusetts, and Leesburg, Virginia. The project time frame is approximately six months. Deliverables include PowerPoint presentations for use by ICPI members.
Fall – Winter 2015
Paving Slab Structural Design is First in the U.S. and Canada
Segmental Paving Slab Modeling/Structural Analysis – Concrete paving slabs are units that require two or more hands to install. These units are seeing increased use in residential, commercial and municipal applications especially with some exposure to vehicular traffic. Applied Research Associates, Inc. will develop pavement thickness recommendations for paving slabs, thin paving units and paving planks. The recommendations will be developed for various bedding, base and soil types. The project reviewed international research and design literature, and then conducted finite element modeling. Delivery is expected in the fourth quarter of 2015. The charts will be included in an ICPI Tech Spec on paving slabs structural design.
Designer Confidence Raised with Validation of PICP Subbase Thickness Design Charts
Full-scale accelerated load testing at UC Davis developed more cost-effective subbase designs for PICPUniversity of California Davis PICP Full-Scale, Accelerated Load Tests.
The final report is on http://www.ucprc.ucdavis.edu/PDF/UCPRC-RR-2014-04.pdf. The deliverables include PICP subbase thickness design charts that validate those published by ICPI in 2011 based on AASHTO 1993 flexible pavement design method. A benefit of the UC Davis design charts is that they provide thinner and more economical subbases in semi-arid climates since the thicknesses are based on the number days the subbase has water in it. The research report was presented to Caltrans on July 29, 2015 and Caltrans agreed to include the UC Davis design charts in their Pervious Pavements Design Guide. The design charts are also in the draft ASCE PICP national design standard which will likely be completed in 2016. The UC Davis work is being published and presented at various conferences including ASCE, the 2015 International Conference on Concrete Block Paving in Dresden, and at the Transportation Research Board meeting in 2016.
PICP Works in Low-Infiltration Clay Soils
This small PICP in Durham, NC demonstrated PICP’s ability to work in low infiltration clay soils
North Carolina State University PICP Monitoring Research – Multiple studies have shown PICP is an effective tool to improve stormwater runoff hydrology and water quality when sited over high infiltration soils. This project research PICP efficacy over nearly impermeable soils (approximately 0.01 in./hr or 0.254 mm/hr) or in Durham, NC from March 2014 through April 2015. Four parking stalls (540 ft2 or 50 m2) were retrofitted with permeable interlocking concrete pavement (PICP) with a very small contributing impervious area. PICP design followed design guidelines outlined in Chapter 18 of the North Carolina Department of Environment and Natural Resources (NCDENR) BMP manual.
Results through 13 months of monitoring indicated 22% volume reduction via subgrade infiltration and evaporation. Inter-event drawdown of the 150 mm thick subbase created storage to capture over 70% of the runoff volume from storm events less than 0.30 inches, and peak flows were significantly reduced by a median of 84%. The site exhibited exceptional pollutant removal efficiency, with influent and effluent pollutant concentrations significantly reduced for TSS (99%), TN (68%), and TP (96%). The median effluent concentrations of TN (0.52 mg/L) and TP (0.02 mg/L) were below “excellent” ambient water quality thresholds for the North Carolina piedmont regions. The median TSS effluent concentration was also very low (6.99 mg/L) and approaching irreducible concentrations.
Additional sampling of the various nitrogen forms 12, 36, 60, and 84 hours post-rainfall was conducted to better understand mechanisms of nitrogen removal in permeable pavement; results from one storm event indicated denitrification is likely occurring in the internal water storage of the pavement. Significant event mean concentration reductions for the metals Cu (79%), Pb (92%) and Zn (88%) were also observed. Cumulative loading reduction for the watershed was excellent with loading removal efficiencies of 98%, 73% and 95% for TSS, TN, and TP, respectively. These results show permeable pavements built over low-infiltration, clay soils provide considerable improvement of water quality and moderate hydrologic mitigation.
Monitored data were also used to calibrate DRAINMOD, a widely-accepted agricultural drainage model, to predict the cumulative and event-by-event hydrologic performance of the study site. DRAINMOD accurately predicted runoff volumes from the impervious drainage area; NSEs exceeded 0.98 for the prediction of inflow during calibration and validation of the site. Good agreement between predicted and measured drainage was also observed. Cumulative predicted drainage volume was within 6% of what was measured during the monitoring period. These results indicate DRAINMOD can be applied to predict the water balance of permeable pavements built over low-infiltration, clay soils on a long-term, continuous basis.
Supporting Landscape Architects Need for Landscape Performance Instruction at Universities
Landscape Architecture Foundation (LAF) mini-grants to teach landscape performance – Ten university landscape architecture programs were granted money to teach landscape performance, document the syllabus, class/studio assignments, student deliverables and reflections. This project accelerates awareness and practice of evaluating the performance of landscape designs as landscape architecture professional practice is using this approach in selling services and in the design process. These deliverables are posted on the LAF landscape performance website at http://landscapeperformance.org/resources-for-educators. LAF hosted a webinar on these deliverables and recording is available for review. The material includes some performance evaluations of PICP and ICP. Overall, there is a wide range of models used by students to characterize landscape performance by practicing landscape architects, academics and students.
Articulating Landscape Performance of Segmental Concrete Paving Systems
Enhancing the LAF Landscape Performance Series Website with Performance of Segmental Concrete Pavements – A three-year grant supports expansion of this website to include information and instruction on measuring performance of segmental pavements. This includes providing case study ideas, curating case study collections, providing input on social media and blogs, and development of online learning modules for on measuring performance of segmental paving products. Click here to vist the curated case study collections.