Guide to Cracksealing
Contents
1. See Sealant Application Cold applied sealants are economically sound for smaller jobs but do not provide economic benefits on high volume projects These sealants are typically packaged in gallon measurement pails drums or stick form 3 Silicone Crack Sealant These types of sealants can be used for sealing expansion saw cuts Silicone sealants are applied using bulk or tube dispens ers and are typically packaged in drum pail or tube form The Table is a general reference for purchasing hot pour crack sealant in 30 pound blocks to accommo date particular crack widths lengths and depths One 30 pound block is equivalent to 3 gallons Check the sealant s product data sheet for specific information Contractors and municipalities should always know the job specs before purchasing the sealant lt is rec ommended that the purchaser account for field waste and purchase 10 to 15 percent more than the required quantity Z lt lt LLI Vv LLI L O Z lt LL I Some sealants are designed to perform in a direct fire melter These models feature direct heat without the use of heat transfer oil and are for low volume applications 26 Most contractors and municipalities prefer to use hot sealant in place of cold pour sealant because cold sealants in general have a high shrinkage property Sometimes heated sealant is necessary for a particular job because the air temperature is too cold or the crack is larger2. www cimline com
3. and a shadow vehicle are highly recommended Throughout the project the safe storage of eguipment and materials in the work zone is necessary When operating cracksealing eguipment and accessories crews must be conscious of their safety Flying debris hot seal ant and heavy eguipment operation reguire focus Eye protec tion is a must and full face shields are sometimes necessary Long pants long sleeved shirts and gloves that fit tight all the way up onto the forearm prevent injury from hot eguipment and sealant Hard hats also provide protection Cracksealing eguipment and accessories are engineered with safety features that promote operator comfort and prevent accidents on the job site For example some melter applica tors feature fume reduction systems which draw the majority of asphalt fumes by convection back into the burner exhaust This mixture is dissipated more thoroughly through the exhaust stack reducing harmful air pollution Several models also feature noise reduction systems Recent melter applicator models also ensure operator safety and comfort through low overall height and stability systems that meet transportation safety guidelines Saws routers and other cracksealing tools have automatic kill switches and brake systems to prevent injury Crews should always avoid the use of alcohol and drugs when on the job Longitudinal V x U LL O V n a gt Transverse Reflective Pavement
4. hot and cold applied seal ants minimizes water penetration sub surface ice formation and traffic erosion Most importantly cracksealing lengthens the life of roadways parking lots and patios made of asphalt or concrete According to several of the country s DOTs with timely preventive cracksealing the useful life of highway pave ments can be extended up to 0 years in comparison to other temporary surface treatments such as chip seals micro paving thin overlays and slurry seals As an added benefit crackseal ing is executed at one sixth the cost of conventional pavement rehabilitation or reconstruction Keep in mind cracksealing is preventative maintenance not reconstruction When a roadway or parking lot is alligatored or has incurred more extensive damage than a few cracks the area must be cut out and replaced or patched gt LLI TS lt u Low loading heights and loading doors positioned above the fenders of the model supply correct ergonomics prevent ing repeated stress and lifting injuries A properly designed angled loading door when closed quickly prevents splashing of hot sealant 08 Especially on busy highly congested roads traffic and workzone safety is extremely important First traffic movement should be inhibited as little as is practical The use of traffic control devices to guide motorists through approaching construction should be implemented The use of arrow boards strobe lights cones
5. than can be maintained with a cold pour sealant see Choosing a Sealant Eguipment Sealant melters are known as double jacketed oil jacketed or double boilers Generally these machines use heat transfer oil as a medium to heat the melting chamber which heats the sealant This system eliminates burning and keeps the melting chamber at a consistent ideal temperature between 350 and 410 F Some melters have a recirculation feature that draws hotter sealant from the bottom of the tank and circulates it back to the top to mix with cooler material Recirculating material this way speeds the melting and heating process and prevents temperature stratification This feature is particularly important when using fiberized sealant or a sealant with min eral filler when constant mixing and agitation is necessary to ensure that components are distributed and the sealant will perform Z lt q l lt LLI V LLI I H O Z lt LLI E Some melters work by recirculating sealant from the bottom back to the top ensuring consistent sealant temperatures 28 Melters are typically skid or trailer mounted and melter appli cators are eguipped with a material delivery or pumping sys tem This system includes single or double hoses with wand attachments that are used to apply the heated sealant directly into the cracks Hose and wand application take the place of witches hats or pour pots See Sealant Application Direct fire kettl
6. cracks appear in several different shapes Inset An alligatored pavement should not be cracksealed This type of deterioration requires removal and repair 10 Transverse Reflective Cracks Cross either from shoulder to shoulder or from shoulder to centerline Caused by inability to redistribute stresses that occur along pavements width and length as temperature increases Longitudinal Cracks Run the length of the pavement roughly parallel to centerline Caused by inability to redistribute stresses that occur along pavement s width and length as temperature increases Block Cracks Block or square pattern spaced between 4 and 12 feet Caused by traffic load and volume or by failures in base or subgrade materials Alligator Map Cracks Pattern that resembles alligator skin or road map Caused by serious deterioration of road cannot be saved by cracksealing Parking Lot Cracks Block type random fashion 10 to 20 feet apart Caused by pavement aging oxidizing or shrinking Sometimes caused by sub base failure this issue should be addressed from the sub base up Z O d a amp Lu cc A xX U Routers are typically used to widen and deepen existing ran dom cracks in Asphalt Concrete Pavement ACP 12 Preparation of pavement cracks is important in successful sealant application Routing or sawing random cracks prior to installation provides clean surfaces for sealant application and a 40 percent gr
7. d the machinery involved are important elements for an effective seal Techniques and equipment vary at this stage in the crack sealing process and application is dependant upon the type of sealant and the machinery available to the contractor or municipality Hot Pour Sealant Tools Once the sealant is heated See Heating the Sealant some professionals use a cone shaped pour pot or witches hat to receive the material The pot is carried over the cracks with the bottom valve open during installation When using a melter applicator heated sealant can be applied through a delivery hose and wand Some models are available with non heated or heated hose options for higher production Working with heated materials requires operator concentra tion and proper attire see Safety Z O d U a a lt Z lt lt LLI Vv rs YA Tt AS riski akli as Sealant should never set higher than 1 8 above the pave ment level V shaped squeegees allow crews to flatten the sealant over the crack and remove excess This is a particu larly important step when cracksealing pavement that will eventually be overlayed with SuperPave 32 Method Contractors and municipalities have their own methodology for sealant application The crack should be filled about three guarters of the way then allowed to cool During this pro cess the sealant will shrink in volume 1476 After the cooling period the crack should be compl
8. e Armed with effective crack cleaning eguipment some professionals skip the routing or sawing step of crack preparation and move directly into cleaning known as blow and go However skipping the routing sawing step in crack preparation is not recommended Crack cleaning eguipment is designed to remove everything from small particles to gravel and sand with powerful air pres sure and suction methods Compressed air can be used to loosen and remove dirt easily Some professionals prefer the use of back blowers to clean cracks Most municipalities prefer the high pressure air from a standard full size air compressor for crack cleaning and other general use A vacuum sweeper also removes fine dust while larger particles can be removed with a broom or mechanical sweeper at the end of the cleaning process Sweeper bristles vary depending on the manufacturer but large capacity mechanical broom sweepers with poly wire mixtures are the most durable and reliable U Z Z lt F lt Lu T A hot air lance or heat lance combines super heated air with compressed air to clean the crack sides remove mois ture and heat crack sides to create a better surface for seal ant adhesion 18 The chances of good sealant bonding are reduced by several factors including cold temperatures dirt and moisture To create a clean dry surface The Strategic Highway Research Program SHRP recommends that cracks be treated with a heat lance or h
9. e Pavements PCCP These sealants come in two different varieties Direct fire sealants are designed to per form in direct fire kettles where heat is imposed directly onto the sealant Oil jacketed varieties are designed to melt under the influence of kettles that use heat transfer oil as a medium where there s less chance for burning and scorch ing Contractors and municipalities should be aware of the type of melter available to them Hot pour sealant can be a good investment on any size project How much sealant to purchase can be calculated with a hot pour crack sealant coverage calculator once a contractor or municipality receives job specs Sealant blocks or biscuits weigh approximately 30 pounds and are individually wrapped in polyethylene bags Crack Joint Specs E Z lt d lt q m 77 lt O lt V 0 0 ur U 19 Ibs block 28 Ibs I block 39 Ibs 2 blocks 48 Ibs 2 blocks 58 lbs 2 blocks 65 Ibs 3 blocks 75 Ibs 3 blocks 94 Ibs 4 blocks 111 Ibs 4 blocks 24 2 Cold applied thermoplastic materials These types of sealants are rubberized asphalt emulsions with mineral fillers used for narrow cracks up to 3 4 inch in width in ACP or PCCP pavements These sealants cannot be used when rain is in the forecast or when temperature is or will drop below 50 E Cold pour crack sealants usually require stirring and can be applied with a pour pot or pressurized crack filler equipment followed by a squeegee
10. eater chance of sealant success Cutting the pavement along the crack lines provides a reservoir for sealant in smaller cracks and an intact sidewall for adhesion Some industry professionals skip this step and move on to the cleaning process a method known as blow and go However routing and sawing cracks before sealant installation is recommended and will eventually become a job specifica tion reguirement Cracks will need to be prepared with a router or saw before installation creating a smoother deeper reservoir for sealant installation A clean or concave surface will be required in anticipation of the installation of the new SuperPave system See Sealant Application Without routing or sawing before sealing the new technology s performance could be compromised Routing Routers are typically used to widen and deepen existing ran dom cracks in Asphalt Concrete Pavement ACP Routers are equipped with a rotating drum with bits These bits can be configured for wide or narrow cuts on the job site and allow for maneuverability in mid cut and adjust with a screw feed to the necessary depths Z Q q a amp LU cc 0 S U Crack saws are most commonly used in Portland Cement Concrete Pavement PCCP for pavement maintenance before sealant installation and in new concrete construction 14 Because flexible pavement highways endure more movement they reguire different routing depths depending on crack spac ing G
11. enerally cracks should be cut to a depth half the length of the width Some sources recommend different cutting depths depending upon crack spacing and the kind of traffic the pavement endures When spacing exceeds 40 pavement cracks experience more stress and should be cut to 1 25 wide by deep Parking lot pavement moves less than highway pavement and typically requires cutting 75 to wide by 75 deep As a rule of thumb a routed crack should never be more than deep When routing is completed the widened cracks should have a square cut with no rough edges Routing should not be executed on cracks that have been previously sealed Sawing Crack chasing saws use diamond blades that produce clean straight lines and are used for crack chasing or slab sawing in Portland Cement Concrete Pavement PCCP Crack chasing requires 5 to 8 diamond blades to allow for maneuverability and accuracy Cracks should be cut 1 2 to deep for sealant installation Sawing is also used in new concrete construction as prevention against cracking Saw cuts should be 2 to 3 in depth Saws typically do not widen cracks beyond 1 4 to 3 8 U Z Z lt LI U Back blowers are popular tools for crack cleaning High pressure air removes dust gravel and other contaminants 16 Contamination in a pavement crack can cause poor sealant bonding Dirt dust and remnants from routing and sawing need to be removed to provide a clean surfac
12. es also provide fast sealant melting for smaller volume projects These models do not employ the heat transfer oil and require specific types of sealant Depending on the size of the project and the capacity of the kettle feeding the melting chamber may require more than one person Larger volume projects may require two workers to feed one or both sides of the kettle Well designed melter applicators feature one or more loading doors depending upon melter capacity and job requirements Angled loading doors provide for easy opening and along with a quick closing motion prevent splashing of hot sealant Loading heights as low as 47 inches minimize operator fatigue Ideal Temperatures Manufacturers instructions will advise you on how hot the sealant should be upon application Typically the recom mended application temperature will range between 350 F and 410 F An infrared heat gun is an excellent instrument to assure ideal sealant placement temperatures and assure quality control NOI LVOlIddV LNV1V3S As it cools sealant shrinks in volume 14 percent 30 One of the most important aspects of sealant application is timing In severe hot or cold temperatures pavement compo nents react and sealant performance is not ideal Air tempera tures between 45 and 65 F put the cracks in the middle of their working ranges so spring and fall provide the best tem perature range for crack sealing Knowledge of application methods an
13. etely filled Some profes sionals suggest the overbanding technique where the sealant is allowed to band over the crack approximately a l 2 out onto the pavement on each side These techniques ensure that the crack is more efficiently sealed from infiltration of moisture The sealant should never set higher than 1 8 above the pave ment level where it can be picked up by snowplows and other pavement cleaning equipment To prevent a convex form from setting a U or V shaped squeegee or a sealing shoe can be applied to flatten the sealant over the crack and remove excess sealant The squeegee creates a sort of concave seal allowing for contraction and expansion of the pavement dur ing extreme temperature conditions Eventually concave application techniques will become a requirement due to the acceptance of the Superior Performing Asphalt Pavements System SuperPave in the United States The SuperPave system is comprised of a patented large aggregate mix design conformed into thin layers Because of the larger aggregate components and thin body of the pave ment overbanded cracks can contribute to compaction and segregation issues on SuperPaved roads and therefore is not recommended STEP INSTALLATION Sealant Reservoir Z O d U pa a lt Z lt q l lt LLI u STEP 2 OVER BAND Sealant Reservoir Step Installation Fill the crack 3 4 wit
14. h sealant Allow to set Step 2 Overbanding Fill the rest of the crack allowing some sealant to overband Use a squeegee to flatten excess sealant Cold pour sealant application In general cold pour sealants must be mixed well before using and can be applied as is Popular technigues vary Operators can use a pour pot a caulking gun or apply the sealant with a putty knife directly from the pail Pressurized spray applica tion eguipment can also be used These machines are capable of spraying pavement sealant with sand added and provide continuous agitation and mixing to maintain a homogenous consistency Fill cracks completely then scrape away excess using a U or V shaped squeegee or a putty knife The surface can be sealed only after the filler has cured Silica sand is sometimes used to promote adhesion to pavements particu larly in hot climate conditions O Z O l m Some cracksealing work is blotted with tissue paper applied with a rolling tool In ideal situations traffic should be kept off the newly crack sealed surface until the sealant has had time to cure or tack This will minimize any tracking and allow for maximum adhe sion to the surface To allow traffic onto the surface sooner blotting the crack is acceptable There are three general meth ods for proper blotting I Several forms of liguid chemicals are available that can be sprayed over the newly installed sealant to speed the tacking p
15. ly placed in crack through standard application equipment 2 Adhesion to remain bonded to asphalt and concrete crack faces 3 Resistance to softening and flow at high pave ment temperature 4 Flexibility and extensibility to remain bonded to crack faces when extended at low temperatures 5 Elasticity to restrict the entrance of foreign noncompressible materials 6 Resistance to degradation from weather 7 Low cure time 1LNV1V3S V SNISOOHO The sealant should come from an approved source or one listed on the Qualified Products List OPL a state provided resource that sets the standard for safe quality products for pavement maintenance According to tests conducted by the American Society of Testing and Materials ASTM the American Association of State Highway and Transportation Officials AASHTO and federal agencies the best perform ing sealant is a polymer modified sealant that relaxes during full extension placing less stress on the bond of the sealant Sealants should always be field tested before installation Operators must ensure that the sealant packaging is not dam aged There are three major categories of crack joint filling materials I Hot applied thermoplastic materials a k a Hot melt crack and joint sealant The primary components of these sealants are asphalt cement polymer reclaimed rubber and mineral filler They are for use on Asphalt Concrete Pavements ACP or Portland Cement Concret
16. ot air lance before sealant installation Hot air lances are designed to mix propane and compressed air to produce hot air Depending on the manufacturer heat lances output flame or flame free heat These accessories generate upwards of 2 000 F to remove moisture and provide addi tional cleaning to the cracks Heat lances normally require more cubic feet per minute from air compressors than stan dard blowers Check your equipment specs In most cases a heat lance is mounted to the truck pulling the kettle The placement on the front of the truck allows operators to heat the crack immediately before it is sealed Operator attention is required at this step in the process the crack should be thoroughly heated but not burned Z lt lt LLI Vv lt O Vv O le I U This particular hot melt crack and joint sealant block is the eguivalent of 3 gallons of melted sealant The block weighs approximately 30 pounds equaling 10 pounds per gallon 20 Understanding the components and performance reguire ments of a sealant is extremely important If the wrong type of sealant is used the economic benefits of cracksealing versus other forms of maintenance or restoration are no longer appli cable The appropriate sealant varies with each job depending on issues such as climate and vehicle and pedestrian traffic In any case there are basic properties that are necessary for acceptable performance I Easily and proper
17. rocess 2 Limestone dust can be applied to the new cracksealed joint 3 Tissue paper is applied directly onto the fresh sealant with a special tool and allowed to disintegrate Once the crack is blotted traffic can resume within minutes O Z Z q Lu U lt Z TS Small portable self propelled brooms are perfect tools for final cleaning of cracksealed surfaces Most pavement maintenance or restoration jobs reguire fur ther steps such as sealcoating overlays or striping These projects require a clean surface Once the sealant has set a broom or sweeper is necessary to remove fine dust gravel dirt clay and other debris from the working surface Powered sweepers can normally complete the job LU U cc 0 71 Lu cc For further materials and resources the following organizations and government departments provide literature and access to archived research projects 1 U S Department of Transportation www dot gov 2 Federal Highway Administration www fhwa dot gov 3 Strategic Highway Research program www wsdot wa gov fossc ota shrp 4 Long Term Pavement Performance program www tfhrc gov pavement Itpp Itpp htm 5 Foundation for Pavement Preservation www fp2 org 6 Cimline Incorporated www cimline com Cimline Copyright 2003 Edition 03 For more information on Cracksealing Equipment Cimline Incorporated 2601 Niagara Lane Plymouth MN 55447 phone 800 328 3874 fax 866 557 197
18. the GUIDE to CRACKSEALING the GUIDE to CRACKSEALING Cracksealing is one form of preventative pavement maintenance that ensures the consistent operation of our nation s roadways Contractors and munici palities extend the life of our highways and parking lots and save taxpayer money with cost effective cracksealing materials and devices For ideal sealant performance crews must be educated on the prop er use of cracksealing eguipment and accessories the proper sealant application and the importance of job site safety SLNALNODO dO 419dVL Why Crackseal Safety Types of Cracks Crack Preparation Cleaning Heatlancing Choosing a Sealant Heating the Sealant Sealant Application Blotting Final Cleaning Resource 06 08 20 26 30 36 38 40 5j lt m V xX U gt L 3 Cracksealing lengthens the life of our nation s streets high ways parking lots and patios made of asphalt or concrete 06 Pavement cracks develop due to expansion and contraction caused by temperature fluctuation These cracks allow water to penetrate the pavement base and sub base materials caus ing pavement elements to lose structural integrity If not repaired or prevented this cracking effect will grow leading to deformation of the pavement pot holes and ultimately the degradation of asphalt and concrete surfaces Cracksealing is preventive maintenance against water from further damaging roads The use of
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