THE OFFICIAL PUBLICATION OF THE INTERLOCKING CONCRETE PAVEMENT INSTITUTE
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LARGEST PICP STREET PROJECT SELF-COMPACTION MYTHS TECH SPEC UPDATES FOUNDATION RESEARCH GRANTS
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EXECUTIVE DIRECTOR: Charles McGrath, CAE PUBLISHING DIRECTOR: Steven Hawkins EDITORIAL DIRECTOR: David R. Smith CONTRIBUTING EDITOR: Robert Bowers, P.Eng. Issue 1 • 2020
DESIGNER: LLM Publications
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contents 02 LARGEST INSTALLATION OF PERMEABLE INTERLOCKING CONCRETE PAVEMENT FRAMES IDAHO DEVELOPMENT
DEPARTMENTS ICPI Webinar Seminars Register at: www.icpi.org/view/events
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Tel 703.657.6900 Fax 703.657.6901 Email icpi@icpi.org ICPI Canada P.O. Box 1150 Uxbridge, ON L9P 1N4 Canada SUBSCRIPTION AND MEMBERSHIP: Qualified design professionals can receive a complimentary subscription—email us at icpi@icpi.org. For further information about this publication or about membership in ICPI, write to the appropriate address, call 703.657.6900 or fax 703.657.6901. Send story submissions for consideration to dsmith@icpi.org. Manage your subscription at www.icpi.org. Interlock Design is published quarterly by the members of the Interlocking Concrete Pavement Institute (ICPI) for producers, suppliers, contractors, specifiers and users of interlocking concrete pavements. The opinions expressed in Interlock Design articles are those of the authors and do not necessarily represent the position of the editor or ICPI.
01 INTERLOCKUTOR CHATEAUBRIAND TO CHICKEN NUGGETS 08 ENGINEER’S VIEW THE MYTH OF SELF-COMPACTING AGGREGATES
ADVERTISING
10 FEATURE TECH SPECS UPDATE
DESIGN
16 FOUNDATION ICPI FOUNDATION ISSUES GRANTS TO ADVANCE THE INDUSTRY
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14801 Murdock Street, Suite 230 Chantilly, VA 20151
20 MAIN EVENTS 20 ADVERTISER INDEX
Ronnie Jacko 503.445.2234 | ronnieJ@llmpubs.com Stephanie Pendell stephanie@llmpubs.com The acceptance of advertising in Interlock Design magazine does not constitute or imply the endorsement or recommendation by ICPI or its members, staff, editors or the publishers of any product or service mentioned, referenced or advertised in the publication. ICPI accepts no responsibility for any claims made in any advertisement. ICPI further reserves the right to refuse to accept any advertisement. ISSN 1087-9862 ©2020 Interlocking Concrete Pavement Institute. Visit our website at www.icpi.org.
interlockutor Chateaubriand to Chicken Nuggets
A David R. Smith
fter 26 years of magazine issues, 104 to be exact, we are saying see you later. Not good-bye, but we hope to see you later on www.icpi.org. This change is an effort to further make the ICPI website the focus for practically all ICPI/ industry news, contractor education, and designer resources. We will be changing to shorter formats of singular case studies and project articles to place on the ICPI website, or with other digital and print publications. From a personal perspective, the Internet is increasingly driving information delivery and not paper. This is good and bad. The good part is inexpensive, easy digital access for publishers and readers. The bad part is a prerequisite Internet connection and TMI. Internet connectivity is almost, but still not quite ubiquitous. There’s TMI such that reading magazines has morphed into scanning Internet articles. Hence our move to chicken nugget-sized information of discrete articles and videos on the ICPI website rather than a more leisurely four-course meal of articles in this magazine. As editor since 1994, I’ve enjoyed being your main chef. Some great sous chefs have helped. Each magazine issue had a different menu with appetizer, first course, main course, dessert and sometimes an aperitif. The content ranged from a salad, occasional chateaubriand, and then a chocolate souffle. A few really meaty issues came with decent wine. We hope you enjoyed the range of subjects, some technical and some more poetic and metaphorical. That’s been the beauty of this effort: writing and illustrating segmental concrete pavement intersects and integrates these places. That’s what makes a good restaurant as well. Au revoir à nos fidèles lecteurs, David
Paving slabs serve as an artist’s canvas in Ülm, Germany. The text under the chalk images reads, “Thank you for your appreciation.”
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ï‚¢ COVER STORY
Largest Installation of
PERMEABLE INTER CONCRETE PAVEM Frames Idaho Development By Sheryl S. Jackson
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PROJECT CREDITS owner:
RLOCKING MENT When completed at 900,000 sf, PICP streets throughout BridgeTower West development aims will be the largest PICP installation in the U.S.
COTTONWOOD DEVELOPMENT LLC, VIOLA, ID
designer:
MATT MUNGER, P.E., WHPACIFIC, BOISE, ID
contractors:
NORTHWEST HARDSCAPE SPECIALTIES, MERIDIAN, ID IDAHO MATERIALS AND CONSTRUCTION, NAMPA, ID
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hen completed with almost 900,000 sf of permeable interlocking concrete pavement (PICP), the master planned community of BridgeTower West, a 500-acre residential development in Meridian, Idaho, will be the largest installation in North America. Although residential neighborhood roads are typically asphalt in Meridian, BridgeTower West’s developer wanted PICP’s upscale appearance. While some developers choose pavers only for sidewalks, crosswalks or driveways, BridgeTower West’s developer placed them in the street. That decision emerged from confident use of durable concrete pavers for communities in California. With 14 development phases, the first two phases enabled engineers and contractors an opportunity to tweak the PICP design after evaluating paver performance. “The first phases installed by a different contractor were designed with some features that did not allow the pavers to perform appropriately,” says Blaine Bergin, president of Northwest Hardscape Specialties, who installed the pavers after the initial two phases.
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COVER STORY
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The initial phases followed more traditional road design with curbs and gutters that concentrated rainwater and sediment runoff into one area versus disbursing them evenly across the pavement. The result was some surface clogging. Recognizing lessons learned, the design was slightly reworked to improve drainage into the subgrade. These changes consisted of new road profiles, a custom curb design and isolated infiltration areas to increase overall system
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Machines accelerate installation of concrete pavers by placing about a square yard on screeded No. 8 stone. Upon installation, the joints are filled with permeable aggregate and the surface is compacted.
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Photo courtesy of Blain Bergin
performance, explains Pete Wilson, construction manager for Idaho Materials and Construction, the general contractor. The 3 1/8 in. thick concrete pavers were supplied by an ICPI member and layers machine-placed over 2 in. of No. 8 stone on top of 4 in. of No. 57 stone. The subbase reservoir ranged between 12 to 16 in. of No. 2 stone separated from the soil subgrade with geotextile that also covered the sides of the excavation. This provided sufficient storage for the average 11 in. of annual rainfall delivered mostly during the winter and spring. The thick subbase layer stores and slowly infiltrates water into soil subgrade, as well as providing
structural support for traffic. Because the area has silty sand soil with a high water table, drain columns that added infiltration were strategically placed every 250 feet under the sidewalk to collect and direct water into the reservoir, says Mr. Bergin. There were no local stormwater regulations requiring PICP use. However, the project was designed to handle stormwater runoff to ensure a long-lasting permeable pavement system. “Use of PICP to handle stormwater eliminated the need for catch basins, piping and surface ponds,” says Matt Munger, P.E., Director of Development Services for WHPacific, who served as design engineer for
the project. “Runoff from driveways and sidewalks are accounted for in the calculations because they directly connect to the paver system,” he says. Although roof runoff may get to the system, it flows across the landscaped areas first, which reduces the amount of water from roofs, he adds. “The local highway district has jurisdiction on stormwater and prior to this project had used or allowed pavers in their right of way,” says Mr. Munger. “Since this project they now allow the use and even specify them on select internal projects.” Utility work was completed before Mr. Bergin’s crew began placing pavers on the road. When his crew approached the concrete collars
The concrete pavers help slow drivers further contributing to pedestrian safety.
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COVER STORY
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around utility covers, “We would lay the pavers by hand at these points, but there was always a height difference,” he explains. “We solved the problem by creating a square metal frame around the manholes and pave up to the frame, and then the contractor would pour concrete.” This simple change made it easier on everyone, he adds. Improperly installed concrete pavers in some city crosswalks in the 1990s created a negative impression among local officials. This impression required convincing PICP use to Ada County transportation department officials responsible for maintenance of the completed roads. To alleviate concerns, the contractor and
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The end of the line for runoff: Rainfall immediately infiltrates into the joints and open-graded base and subbase reservoir, thereby eliminating detention ponds.
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Photo courtesy of Blain Bergin
opinions have changed as some developer posted bonds well of the oldest streets reach five over the standard amount and years of age, says Mr. Wilson. “The warranty period to guarantee the roadway, says Mr. Munger. Although county has taken ownership of the first three phases and there has the warranty for asphalt roads is been little need for repair,” he says. normally two years, the general contractor and developer provided “The first couple of phases were a learning experience, but even a five-year warranty to the county. those streets are in good shape and Traffic Calming Effects handling stormwater well.” “At first, inspectors and other “Personally, I love the product and one of the things that I like the most highway department personnel were hesitant about how well is an unintended benefit,” says Mr. permeable pavers would perform Munger. “The pattern and the joint on a large surface, but now they spacing in the road has a different understand more about how they feel and gives more feedback through the steering wheel than on work and their benefits,” says Mr. Bergin. “Permeable pavers are now a standard road surface making it required on a lot of jobs in the uncomfortable to drive fast.” Since area, including a park-and-ride lot the product was used on local where permeable pavers eliminated streets lined with homes, reduced the need for retention ponds, speeds make the streets safer for giving them use of more land the residents, he adds. for parking.” l Even though county officials were initially wary of PICP roads,
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Issue 1 • 2020
ENGINEER’S view The Myth of Self-compacting Aggregates 12 Rules for Compacting Open-graded Aggregate, An Antidote to Chaos By Robert Bowers, P. Eng., Director of Engineering, Interlocking Concrete Pavement Institute
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A high-force, vibratory plate compactor with a compaction indicator converts open-graded aggregate chaos into order.
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he following is advice on the need for compacting open-graded aggregates such as ASTM No. 2 and 57 stone. They are not “selfcompacting.” Engineers define soil as a naturally occurring, loose/uncemented/weakly cemented/relatively unconsolidated mineral particles, organic or inorganic in character, formed by weathering (disintegration) of rocks or other parent materials. This includes aggregate. The terms compaction, consolidation, and settlement are often used interchangeably. This usage is technically incorrect because they are fundamentally different processes. Compaction is a rapid process where dynamic mechanical pressure from tamping, rolling, and vibration is used to compress a soil mass for improved soil stability. Soil volume is reduced by removing air voids. Consolidation is a slow process where a steady, sustained, static load compresses the soil mass. This can be a naturally occurring process or a soil improvement technique. Soil volume is reduced by squeezing pore water out of the soil mass. Settlement is a long-term process where dynamic forces, like transient loads, seepage, and freeze-thaw cycling act upon the soil mass. Settlement is a naturally occurring process. Soil volume is reduced by removing air voids and water from the soil. With acknowledgement to author Jordan Peterson, here are the 12 rules to help cure pavement chaos:
1. Achieving optimal compaction will reduce the potential for settlement. That is our desired goal. 2. Compaction is used to rapidly adjust the position of the soil particles, reduce the air space between them and interlock them to maximize density and stability. 3. Soil compaction involves two actions: a) Realigning particles relative to each other, and b) Movement of small particles into the voids between larger particles. 4. It takes effort (and time) to realign particles. It takes even more effort (and time) to move particles closer together.
5. Like soil, compaction of open-graded aggregates is about realigning the particles so they fit more closely together, thereby increasing their stability. 6. Compaction of dense-graded aggregates is about realigning the particles so they fit together better while moving smaller particles into the voids among larger particles. 7. Therefore, less effort (and time) is required to compact open-graded aggregate than densegraded aggregates. 8. More energy (larger compactors) is required to realign particles with a greater size (or mass) compared to particles of a smaller size (or mass). 9. In most cases, open-graded aggregates used for base construction are equal in size or larger than the largest particles in dense-graded aggregate recommended for base construction. 10. Following Rule 8, open-graded aggregates generally will require more energy (larger compactors) to achieve optimal compaction compared to densegraded aggregates. 11. The “as-placed” compaction of open-graded aggregates varies depending many factors including drop height, volume of material, moisture content, and particle shape. If you dump many spheres of uniform size into a box, they will be pretty close to optimum density. But, open-graded aggregates, used for base construction, are not spheres. They are angular and not uniform in shape or size. Therefore, they do not find the tightest fitting arrangement by simply being dumped in place. 12. To achieve optimum density, open-graded aggregates must be compacted and not dumped “as-placed” regardless of the layer thickness. Compaction in most cases requires larger compactors (more energy), but fewer passes (less effort), when compared to compacting densegraded aggregates. The actual energy and effort required will vary among different aggregate sizes, shapes and gradations. Open-graded aggregates left uncompacted and simply “placed” will suffer from unnecessary settlement, leading to pavement chaos. l
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Issue 1 • 2020
FEATURE STORY
Tech Specs Update
S
ince its inception in 1994, ICPI published 24 technical bulletins called Tech Specs. They provide salient advices and best practices for design, specifications, construction and maintenance of interlocking concrete pavements, permeable interlocking concrete pavements, concrete grid pavements and paving slabs. These are available for free here. All Tech Specs are reviewed every three years by the ICPI Technical and Construction Committees on a rotating basis. Depending on research and practice, some bulletins see substantive changes while others do not. Both committees recently rendered significant changes to several such that we are reporting on them.
TECH SPEC 2 Construction of Interlocking Concrete Pavements Several edits include assessment of soil moisture before compacting, managing dust during saw cutting, clarification on sand gradations, and maximum lippage of adjacent pavers. Some images and references are updated in this and in other Tech Specs.
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TECH SPEC 4 Structural Design of Interlocking Concrete Pavements
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The only change is deletion of references to Lockpave (v16). Originally developed by Dr. Brian Shackel from Australia, ICPI no longer supports this software because it does not run on Windows 10. Additionally, the text notes ICPI’s free Excelbased structural design software on www.icpi.org that follows Tech Spec 4 and ASCE 58-16 Structural Design of Interlocking Concrete Pavements for Municipal Streets and Roadways.
TECH SPEC 7 Repair of Utility Cuts Within Interlocking Concrete Pavements The new version removed text on temporary, winter-time utility cut repairs in asphalt with concrete pavers as substitute for using cold patch asphalt materials that don’t install well in belowfreezing temperatures. This was an innovative repair method initially developed by contractor Mark Gavigan for utility companies cutting into streets owned by the City of London, Ontario. While a cost-effective approach, the City likely left the pavers in place rather than removing them in the spring and patching cuts with asphalt. In keeping with material differences between asphalt and concrete pavers, the asphalt around these small repair areas in pavers quickly deteriorated and utility cuts returned to using cold patch asphalt. Later in 2020, this Tech Spec will likely see additional information on utility cut costs from two ICPI Foundation projects examining this subject. Also, the title is changed to better reflect the content.
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COVER FEATURE STORY STORY
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TECH SPEC 8 Concrete Grid Pavements The updated version removes references to open-graded bases and discourages their use under grid paving units when subject to vehicular traffic. Grids are concrete paving slabs (with openings) which should be exposed to limited vehicular traffic, i.e. maximum 7,500 18,000 lb lifetime equivalent single axle loads. This requires the use of a dense-graded aggregate base under the grids and bedding sand. Open-graded bases can introduce some instability under repeated tire traffic. If open-graded bases are needed for stormwater storage and infiltration, permeable interlocking concrete pavement is recommended due to its higher load-bearing capacity and stability.
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TECH SPEC 13 Slip and Skid Resistance of Interlocking Concrete Pavements
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This revised version includes additional information on testing for the dynamic coefficient of friction of slip resistance per ANSI A137.12012 American National Standard Specifications for Ceramic Tile and A326.3-2018: Test Method for Measuring Dynamic Coefficient of Friction for Hard Surface Floor Materials. With other test methods noted in this bulletin, these ANSI standards provide another option for characterizing the slip resistance of concrete paving units. There are no changes to text on skid resistance for vehicles as tire-pavement skid measurement methods and skid resistance of interlocking concrete pavement remains similar to that of asphalt pavements.
TECH SPEC 16 Achieving LEED Credits with Segmental Concrete Pavement Many edits were made that updates content from LEED v4 to v4.1. Most changes are under the Rainwater Management and Materials and Resources credits. Fortunately, the US Green Building Council issued a free, 260-page reference guide for v4.1 in early January 2020 and this document was quoted in this Tech Spec. LEED v4.1 makes earning points easier as the more onerous and complex v4 lost some traction among project owners and design professionals. ďƒ¨
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COVER FEATURE STORY STORY
Continued from page 13
TECH SPEC 19 Tech Spec 19 Design, Construction and Maintenance of Interlocking Concrete Pavement Crosswalks This bulletin includes minor edits and updates to a crosswalk section.
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TECH SPEC 20 Construction of Bituminous-Sand Set Interlocking Concrete Pavement
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Additional information on particle sizes and layer thickness for the asphalt bed under concrete pavers are provided. This gives a wider range of options for asphalt mixes.
TECH SPEC 23 Maintenance Guide for Permeable Interlocking Concrete Pavements Updates include clearer advice on using sand for winter traction, street sweeper effectiveness in removing sediment from paver joints, and addition of recently developed, high-pressure air/vacuum surface cleaning equipment and pictures. The latter cleaning equipment is quite effective in restoring clogged PICP surfaces. l
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ICPI Foundation Issues Grants to Advance the Industry By testing deflection, a lightweight deflectometer checks compaction of No. 57 stone for permeable interlocking concrete pavement.
The ICPI Foundation for Education & Research announced two recent grants. The first is called “Developing Deflection Acceptance Criteria for Compacted, Open-graded Aggregate Bases for Permeable Pavements Using Lightweight Deflectometers (LWDs).” A grant of $149,681 was awarded to Oklahoma State University. Quality control and quality assurance of unbound aggregate layer construction in pavements has traditionally been based on measuring density using a nuclear density gauge. Measuring density of open-graded bases for permeable pavements, however, can be highly variable as well as a slow process requiring certified technicians. This research project addresses the need for developing compaction specifications based on deflection criteria measured with an LWD, a technology in existence since the 1980s. This cutting-edge work follows recent development of LWD protocols and an AASHTO provisional specification for deflection measurements on compacted subgrade soils and dense-graded bases. Several state departments of transportation in the US (e.g. Florida, Indiana, Minnesota, Nebraska) have adopted compaction control specifications for these materials using LWDs. The trend toward using LWDs among other state DOTs is growing due to the inexpensive, reliable, and fast nature of the tests.
This research project will model and conduct full-scale tests on a number of open-graded base structures used in permeable pavements and develop specifications for deflection-based compaction control. Work includes a literature review, laboratory tests, field testing, numerical modeling, and a compaction control specification written in AASHTO format for eventual submission to AASHTO. The project will require a year to complete. The second grant is $35,000 to Nocti Business Solutions for creating a job task analysis (JTA) for segmental pavement installation. A significant challenge facing the segmental concrete pavement industry is recognition among project owners, government agencies, design professionals, general contractors, landscape/hardscape installers, and homeowners that segmental pavement installation with its specific techniques is a trade of its own. Other construction trades with established apprenticeship and licensure programs (as well as certifications) have guidance documents that explain required knowledge, skills, and abilities. Such a document is needed to define a competent paver installer, i.e., a JTA. A JTA addresses the most important tasks within a job, documents efficient installation practices, and serves as a legally defensible basis for instructional curricula. Often used to construct and validate certification programs such as those by ICPI, JTAs are the legal and technical basis for establishing industry certification. JTAs also ensure that exam questions are relevant to the job and its required tasks. A JTA can serve as the guidance document for developing an apprenticeship program and justifying the need for licensure of installers by municipal or state building departments. Ultimately, a JTA helps the industry establish that installation profession as a trade. This analysis and report will require about six months to complete. The ICPI Foundation has issued over $1.5 million in research and education grants since its inception in 2000. The Foundation mission is funding targeted educational and research programs and developing tools that benefit the segmental concrete paver industry while supporting the strategic goals of ICPI in a financially sustainable way. The Foundation supports ICPI’s 2019–2022 Strategic Plan which endeavors to: 3Expand a qualified workforce with defined career paths; 3Develop tools that lead to greater adoption of segmental concrete pavements among municipalities and designers; and while doing so, 3Achieve greater recognition of sustainable aspects and technical credibility of segmental paving systems. l
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COVER FOUNDATION STORY
Continued from page 17
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A job task analysis defines the steps required to perform a job the knowledge and skills needed to accomplish them.
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THE MAIN EVENTS
the MAIN events
Issue 1 • 2020
In order to accommodate the needs of many installers registered for courses recently cancelled due to COVID-19 restrictions, ICPI will be launching a temporary online Concrete Paver Installer course in English. The course will launch on Friday, March 20, and transfer fees for affected installers will be waived. To register, please email certification@icpi.org. ICPI’s online training opportunities include a variety of certification and designation courses as well as continuing education webinars. Installers and sales reps alike can earn designations like Residential Specialist or Commercial Specialist right now. Coming soon will be the Residential Professional course for installers/contractors. Visit the ICPI Hardscape Institute to learn more.
EVENTS DATE
EVENT
LOCATION
March 24-25
Concrete Paver Installer Course – Keystone Hardscapes
Houston, TX
March 30-31
Concrete Paver Installer Course (French) – APPQ-Quebec Vert
Laval, QC
April 8
Concrete Paver Installer Course – APPQ
Quebec, QC
April 15
Concrete Paver Installer Course – Basalite
Lakewood, CO
April 28
Concrete Paver Installer Course – Jewell Concrete
Houston, TX
August 24-27
ICPI Summer Meeting
Annapolis, MD
October 21-23
Hardscape North America
Louisville, KY
To check out more ICPI Events, click here.
WEBINAR DATE
WEBINAR/PRESENTER
LOCATION
April 23
Roof Decks with Segmental Concrete Pavements
1:00 pm EST
April 30
Introduction to Permeable Design Pro Software
1:00 pm EST
May 7
Proper Paver Maintenance
1:00 pm EST
To check out more Webinars and On-Demand Learning options on the Hardscape Institute, click here.
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ADVERTISERS IN THIS ISSUE
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Columbia Machine, Inc............................. 21
PAVE TECH Hardscape Outfitters............................15, 21
Standley Batch Systems, Inc............................. 18
KBH Maschinenbau............... 17
Solomon Colors, Inc............... 21
Topwerk .......................................7
KOBRA Molds, LLC..................7
MARKETPLACE
21
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