RoadGrid International Installation Guide Optimized

8/13/2019 RoadGrid International Installation Guide Optimized

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ROADGRID INSTALLATION MANUAL

SEPTEMBER 09 - INTERNATIONAL EDITION


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Roadgrid Installation Manual

Asphalt being durable and economical, is indeed an ideal material for road con-struction today. However the maintenance problems occur when cracks are re ect -ed up into new layers from aged, cracked bottom layers. These types of cracks areproduced due to thermally induced and traf c fatigue. In the case of an asphalt layeron a concrete pavement, re ective cracks can be caused by the horizontal movement of the individual concrete slabs when they expand and contract under the in

uence of temperature variations. These motions cause high strains in the asphaltlayer directly over the concrete joints and lead to cracking. The propagation of these

cracks from the old pavement upwards and through a new overlay, is referred to asre ective cracking . These types of cracks result in a shortened pavement life, aswater is allowed to penetrate the sub layers, and surface continuity is destroyed.The overall result is a reduced structural strength of the pavements.

Traf c introduces both shear and bending forces in the pavements. Crackingis typically initiated when the forces create stresses which exceed the fracturestrength of the asphalt overlay. The other common problems encountered inasphalt pavements are rutting and fatigue cracking. All of these problems canbe solved by employing a suitable asphalt reinforcement technique .

Pavement rehabilitation strategies can be enhanced with a greater success ratewhen combined with drainage improvement features, such as edge drains,and other improvements such as surface and crack sealing, full depth asphaltreclamation, subgrade reinforcement, subgrade repairs and reclamation, sub-grade drainage, as well as suf cient overlay asphalt thickness for the designloads. Where an overlay is too thin for the application, or on an unsuitablebase structure, re ective cracking is assured to occur.

For many years, there have been investigations where the use of interlayers withinthe overlays are used to reduce the effects of re ection cracking, by dampeningstresses, relieving strains, and by provision of tensile reinforcement.

RoadGridis a speci cally knitted berglass grid with bituminous coating,making it ideal for asphalt reinforcement. Bituminous coating optimizes thechemical compatibility between the ber glass reinforcement and thepavement overlay. RoadGrids encompasses range of products for spe -ci c use; however, all RoadGrids possess extremely high modulus, highstiffness, high creep resistance and excellent shrinkage values (< 0.5% at200 degrees C) along with optimal elasticity modulus of 69,000 MPA foroutstanding performance.

The Bene ts: Minimizes both thermal and stress

related re ective cracking. Reduction of rutting of pavements

subjected to high ambient temper-atures and intense wheel loadings.

Increases the fatigue life of pave -ments with weak foundations.

Reduction of the overlay thickness,with Checkmate RoadGrid, aminimum asphalt overlay thicknessof 40mm can be used.

Provides cost bene ts by increasingthe life cycle of the pavements.

Fast and easy installation. Suitable for all types of asphalt

mixes.

412-44550 South Sumas Road | Chilliwack, British Columbia | V2R 5M3 | Canada | T 1.604.824.4963 | F 1.604.648.9342 | www. checkmategeogrid .c


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The interlayer is composed of a series of berglass strands coated with anelectrometric polymer and formed into a grid structure. Each strand has a re -markably high tensile strength and high modulus of elasticity at low elonga -tion; this is particularly important as asphalt concrete typically cracks at lowstrains. This combination makes RoadGrid even stronger than steel.

In a resurfacing application, RoadGridgreatly assists in minimizing re ec -tive cracking. The RoadGridis sandwiched between the leveling and sur-face course asphalt, it becomes the hidden strength in the road designed toturn crack stresses horizontally and effectively dissipate them.

Checkmate RoadGridRG series has been successfully used for a variety ofasphalt reinforcement applications including control of re ective cracking,fatigue cracking and rutting in asphalt concrete overlays, airport runways,roads, parking lots, jointed concrete highways and other uses.

Design considerations include: Anticipated traf c loading (magnitude and intensity) Thickness and material properties of the existing pavement structure and the

new asphalt overlay Width and spacing of cracks on the existing pavement. Sub-grade soil data Geogrid locations for asphalt reinforcement.

ROAD G RID IS ALSO IDEAL FOR USE IN NEW HIGHWAYS CONSTRUCTION ,SAVING LONG TERM MAINTENANCE FOR THE OWNER AND INCREASING THELIFE OF THE ROADWAY .

Storage and Handling: RoadGrid is to be stored in a dry, covered location that is free of dust dirt and

moisture. The area should be situated such that excessive mud, uid concrete,asphalt, or other deleterious materials are not allowed to contact the reinforce-ment mesh materials.

RoadGrid should be stored at temperatures above minus 20 degrees F (-29degrees C).

If the RoadGrid is stored outdoors, the rolls need to be covered with properwater proof covering.

Surface Preparation: The existing pavement should be clean and dry, with an even surface. Any cracks exceeding 0.25in. (6 mm) in width should be sealed using an ap -

proved sealant or the appropriate leveling course mix. Potholes and failed or cracked sections of pavements shall be repaired as

instructed by engineer. RoadGrid should not be installed directly over the milled surface. The min -

imum treatment should be cleaning and repair of cracks and potholes, ap-plication of leveling course and the application of tack coat. ( unless adhesivetype RoadGrid is used )


Engineers have been successfully us-ing this solution on a wide range of

pavement types. Parking Areas Low volume roads,

e.g.Country roads Flexible high volume roads,

e.g. Interstates, Highways Rigid high volume roads,

e.g. Interstates, Highways Airport runways, taxiways Aprons Jointed Concrete highways

And other uses.



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A leveling course is required between RoadGrid and Portland Concretepavements.

If the Self adhesive type of RoadGrid is used, there may be no require -ment of Tack Coat.

DO NOT place mesh reinforcement when the surface iswet, or contaminated with oil, soil or excessive dust.DO NOT place asphalt during wet or freezing weather thatprevents conformance with speci ed requirements.

A tack coat is a light coating of liquid asphalt applied either to an existing pavement surface or on top of the installed RoadGrid. It is typically used to bonda new asphalt concrete course to the existing pavement surface. The pavementindustry has been implementing changes to asphalt mixes in order to makethem leaner, stiffer and more rut-resistant. Consequently, these changes andthe need to maximize the bond between lifts have resulted in most authorities

mandating the use of a tack coat between all lifts of asphalt.Speci cations for Tack Coat typicallyfollow the following guidelines:

Type 1 NTSS-1HM, anionic, trackless tack. The trackless tack is not stickywhen cured, reducing the possibility of pickup or build-up on paving equip -ment.

Type 2 Cationic, rapid set, CRS-2P. In general, cationic emulsions can breakand set more quickly than anionic emulsions due to the electrochemical reac -tion between the aggregate and the binder.

Type 3 Hot sprays AC AC20-5TR-PG64-XX. In general, hot spray AC tacks

work well in cooler weather, when surface temperatures are at or below 80F.When surface temperatures exceed 80F, the manufacturer recommends thatan emulsion be applied in place of the hot spray AC.

Tack coat needs to be applied uniformly over the prepared surface at a rateof 0.4 - .6kg/square meter (.39 - .59 liters/square meter) using a calibrateddistributor truck, ensuring that the application rate remains constant. The tackshall contain a minimum of 70% solids.

The width of the tack coat application must extend 75mm (3) beyond theRoadGridon all sides. Emulsions used with RoadGrid must break andthen cure before any additional asphalt is placed. Breaking is de ned as the

point at which the brown colored uid turns black. Curing occurs when theresidual asphalt cement contains no solvents (water or any volatiles).

Milled Surfaces - Hot in Place or Milland Fill Applications:

A minimum 0.75 in. (19 mm) thick asphalt concrete leveling course should beplaced.

Before laying the grid, the surface temperature should be between 40F (5C)and 140F (60C).




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Before placing RoadGrid, the leveling course should provide suf cient adhe -sion to the grid. Tack Coats, described above, are recommended between thelifts for maximum adhesion.

Environmental Conditions: The road must be dry. Do not install RoadGrid during any precipitation.

The road surface temperature must be between 5C* (40F**) and 60C*(140F**). On asphalt surfaces less than 24 hours old, the surface temperatureshould be between 5C* and 46C* (40F** and 110F**).

Cold surface and cold air temperatures are not favored for the RoadGridtoadhere to the tack coat and create a strong surface bond to the existing asphaltlayer. Early morning starts during fall and spring seasons, where ambient airconditions are lower than speci ed; applications of RoadGridshould not beallowed where the temperature does not allow a strong contact bond betweenthe tack coat and the RoadGrid.

Installation Procedures:

There are two primary ways that RoadGrid can be placed on an asphaltsurface. The rst, and more common approach, involves mechanical place -ment, typically with a pickup truck that has been modi ed so that the Road -Grid can mounted on the back. This method is typically used for full-widthinstallations but can also be used for detail repairs that are suf ciently large.

An alternative installation method involves manual placement of the grid Inthis method, although the product is physically placed by hand, it is highlyrecommended that the RoadGrid roll be mounted on the back of a truck orother vehicle to help maintain tension during placement. Manual installationis more commonly used for localized areas of road.

Keeping tension in both the machine direction and the cross direction theRoadGrid is nailed along the starter end (from corner to corner) to the exist-ing asphalt using the desired concrete nails and fender washers. If air pockets




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exist and do not level out after the rubber roller has compressed the Road-Grid into the tack coat these air pockets must be minimized by method ofnailing the center of the raised bubble to the asphalt. Dependent upon thesize of the air pocket several nails may need to be used. Overlooking theseraised bubbles in the RoadGridwill result in re ective bumps in the cover -ing layer and nish courses of asphalt.

Whether RoadGrid is placed mechanically or manually, there are severalgeneral requirements to consider:

The grid must be installed under suf cient tension to reduce or eliminate anyripples. If ripples do occur, they must be removed prior to paving by pullingthe grid tight. In some cases (e.g., on curves with tight radii), it may be necessary to cut the grid in short sections .For sharp curves, cut edges and fold overin the direction of the placement of asphalt overlay.




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Overlap all end roll joints 75-150 mm (3-6). Ensure that the overlaps areshingled in the direction of paving and that these overlaps also receive anapplication of tack. In the longitudinal direction the overlap should be 25-50mm (1 - 2) The overlapping of two lengths of RoadGrid is shown inthe photos.

In order to maximize adhesion with the tack coat surface, the surface of the

grid should be rolled with a rubber coated roller or pneumatic-tired roller.The tires must be kept clean to avoid picking up the RoadGrid during instal-lation. If RoadGrid self adhesive type is used, the surface of the RoadGridrolled with such a roller, with one or two passes activates the self adhesive.

Construction and emergency traf c may travel over the RoadGrid once ithas been placed and rolled, but turning and/or braking must be avoided at alltimes. Any damaged sections caused by construction traf c must be removedand patched prior to paving. It is also important that the RoadGrid be keptfree of mud, dust and other debris during construction.

Paving Overlay: Roadgrid performs best on a levelling course. The Roadgrid should be placed

on smooth, level, asphaltic surface.

A minimum of 19mm ( 3/4 ) levelling course of asphalt is recommended onconcrete surfaces without an existing overlay.

The Roadgrid can also be placed directly over the existing asphalt surfaceand in that case tack coat is highly recommended. The tack coat must alwaysbe cured before Roadgrid or asphalt concrete is applied.

Paving must take place the same day RoadGrid is installed within permis -sible laying temperatures to a minimum compacted thickness of 40 mm (1.5inches).




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Design Guidelines:Checkmate has design guidelines for ascertaining overlay thicknesses, deter -mining crack widths and required geogrid overlays, and determining traf cbene t ratios. This information can be obtained from the website, at www.checkmategeogrid.com, or from a Design / application engineer at Check-mate Geosynthetics Inc. You may also refer to our RoadGrid Technical De -sign Manual and the RoadGrid Technical Note document available fromCheckmate.

Disclaimer: The information contained herein is to the best of our knowledge accurate, but since the circumstances andconditions in which it may be used are beyond our control, we do not accept any liability for any loss or damage, however arising, which results directly or indirectly from use of such information, nor do we offer any warranty or immunityagainst patent infringement.



RoadGrid International Installation Guide Optimized

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