Department of Architectural and Civil Engineering
Pavement Materials and Design
CVEN 460- L01
Term Project: Crack Treatment
Instructor: Dr. Okan sirinDone by:
Submission date: 21/May/2018
Table of Contents
TOC o “1-3” h z u Abstract PAGEREF _Toc514633190 h 1Introduction: PAGEREF _Toc514633191 h 21. Crack Repair by Sealing PAGEREF _Toc514633192 h 21.1 Crack Repair by Sealing (clean & seal) PAGEREF _Toc514633193 h 21.1.2 General Crack clean & seal procedure: PAGEREF _Toc514633194 h 21.1.3 Crack analysis and identification PAGEREF _Toc514633195 h 31.1.4 Dimensions of pavement cracks for crack sealing PAGEREF _Toc514633196 h 31.1.5 Crack cleaning and preparation PAGEREF _Toc514633197 h 41.1.6 Application of sealant PAGEREF _Toc514633198 h 41.1.7 Squeegee cracks PAGEREF _Toc514633199 h 51.2 Crack Repair with Sealing (Saw and Seal) PAGEREF _Toc514633200 h 51.2.1 Procedure for saw & seal PAGEREF _Toc514633201 h 61.2.2 Properties of the sealant: PAGEREF _Toc514633202 h 61.2.3 Determining the Percentage of Success of Saw and Seal PAGEREF _Toc514633203 h 61.3 Crack Repair with Sealing (Rout and Seal) PAGEREF _Toc514633204 h 71.3.1 Procedure for Rout & Seal PAGEREF _Toc514633205 h 71.3.2 Dimensions of the reservoir PAGEREF _Toc514633206 h 82. Crack Filling PAGEREF _Toc514633207 h 82.1 Crack Filling Procedure PAGEREF _Toc514633208 h 92.2 Crack Filling vs Sealing PAGEREF _Toc514633209 h 93. Full / Partial Depth Repair PAGEREF _Toc514633210 h 103.1 Full-Depth Repair PAGEREF _Toc514633211 h 103.1.1 FDR Procedures PAGEREF _Toc514633212 h 103.2 Partial-Depth Repair PAGEREF _Toc514633213 h 103.2.1 PDR Procedures PAGEREF _Toc514633214 h 103.3 FDR/PDR Repair Boundaries Determination PAGEREF _Toc514633215 h 11Conclusion PAGEREF _Toc514633216 h 11References PAGEREF _Toc514633217 h 12
Table of Figures:
TOC h z c “Figure” Figure 1: Block Cracking on Pavement PAGEREF _Toc514633218 h 3Figure 2: Reflective Cracking on pavement PAGEREF _Toc514633219 h 3Figure 3: Applying sealant using wand PAGEREF _Toc514633220 h 4Figure 4: Squeegee operation PAGEREF _Toc514633221 h 5Figure 5: Test sample with transverse cracks and sawed joints PAGEREF _Toc514633222 h 7Figure 6:Reservoir Dimensions PAGEREF _Toc514633223 h 8Figure 7: Longitudinal Cracking PAGEREF _Toc514633224 h 8List of Tables
TOC h z c “Table” Table 1: Filling vs Sealing Treatment Comparison PAGEREF _Toc514633225 h 9Table 2: FDR/PDR Comparison PAGEREF _Toc514633226 h 11
This project provides brief information regarding three different crack treatments: crack sealing, crack filling and full / partial depth repair. Unlike the latter two treatments, crack Sea1ing involves three approaches: clean & seal, saw & seal and rout & seal. This project also provides procedures for each crack treatment as well as allocating which crack treatment is suitable for various crack types. Types of cracks mentioned in this project will be given a brief description for further elaboration. The importance of this project is to teach the students the importance of crack treatment and to provide awareness of the consequences of not treating such cracks. At the end a comparison between sealing and filling made to distinguish when to use each treatment type.
Introduction:Transportation is considered an essential part of modern society that helped civilization advance to never before seen heights. Land transport is considered to be the dominant means of transportation especially road transport since it is the most used and cheapest. Therefore, it is of great importance to keep pavements in good conditions and fix them if necessary as soon as possible to ensure safety for motorists and pedestrians on the road. One of the major problems engineers face in asphalt pavements is cracks on road surface. Cracks vary in shapes and sizes depending on the environment conditions and the type of loads that are subjected to the pavement. Consequently, engineers have proposed solutions for such problems, such solutions are called Crack Treatment.
1. Crack Repair by Sealing One of the most commonly used and cost-effective type of crack treatment in asphalt pavement is crack sealing. However, unless it is performed properly, the benefits are minimal to the pavement or the traveling public. This treatment is used to stop water and rubble from entering the crack. Water can cause deterioration to the pavement if infiltrated through cracks. Aging can also be accelerated with the provision of these cracks since the oxygen can go through the cracks and cause oxidation and aging to the pavement. There are three different approaches for crack sealing: clean & seal, saw & seal and rout & seal.
1.1 Crack Repair by Sealing (clean & seal)This approach involves using air compressor or hot air lance to blow the small particles from cracks in order to add the sealant in the crack. This treatment usually extends the pavement life cycle for additional three years before the sealant begins to peel off the pavement cracks
Before proceeding with any pavement crack treatment, traffic control must be implemented until the treatment has been fully executed.
1.1.2 General Crack clean & seal procedure:Crack analysis and identification
Crack cleaning and preparation.
Application of sealant
1.1.3 Crack analysis and identificationThis is done to identify those pavements which exhibit the type and severity of cracking that warrants crack sealing. The following types of pavement cracks can effectively be treated using crack sealing (clean & seal) method:
40176452051685Figure SEQ Figure * ARABIC 1: Block Cracking on PavementFigure SEQ Figure * ARABIC 1: Block Cracking on Pavement401812414685300Block cracking (shrinkage cracking)
It is a distress which often warrants crack sealing. Daily temperatures changes cause expansion and contraction in pavement. As the pavement ages and hardens, it is less able to withstand this stress and pulls apart creating blocked cracks. Block cracking begins as transverse cracks, these transverse cracks eventually become connected with longitudinal cracks forming blocks hence the name block cracking. Block cracks are not a load associated pavement distress and do not represent a structural failure of the pavement. However, if these cracks are not sealed properly water can freely enter the base and subgrade, this will weaken the pavement and lead to structural problems.
Usually a crack will form along the joint between the original pavement and the widening strip.
37814252063115Figure SEQ Figure * ARABIC 2: Reflective Cracking on pavementFigure SEQ Figure * ARABIC 2: Reflective Cracking on pavement378142524384000Reflective cracking
This cracking occurs where Portland cement concrete pavement has been overlaid with asphalt. Usually the joints and cracks in the concrete pavement will reflect to the surface, these cracks should be sealed to prevent water and incompressible material from entering them.
1.1.4 Dimensions of pavement cracks for crack sealingCracks must be wide enough for the sealant to enter the cracks. The crack should be approximately 0.25 inch wide. It is not effective to seal all cracks. For very narrow cracks, other sealing techniques such as slurry seal may be used. Some pavement section may have extensive block cracking with small blocks of 2 to 10 feet formed, alternate repair procedures such as chip seals or overlays need to be considered. For these conditions crack sealing would be too time consuming and expensive to be cost effective. The preferred time of year for crack sealing is the winter, when cracks are their widest. However rubberized asphalt sealant makes a year-round crack sealing possible.
1.1.5 Crack cleaning and preparationA clean and dry crack is essential for an effective bond to be formed between the crack sealant and the pavement. The cracks should be cleaned with compressed air or hot air lance. Compressed air effectively removes dust, sand and other incompressible matter from the crack, providing a clean face for bonding. The hot compressed air lance combines high pressure with a flame to heat the air, this dries and clean the cracks at the same time. In addition, the asphalt pavement is heated somewhat and the asphalt binder is softened to aid the bonding of the sealant. The hot air lance also burns away organic matter in the crack that would interfere with a sealant bond. When using the lance, the operator should keep moving so that the lance does not burn and damage the asphalt pavement. The hot air lance ensures a dry surface for the sealant bond. Often the surface of a pavement appears dry but moisture remains in the cracks below the surface, the hot air lance dries this latent moisture.
1.1.6 Application of sealant40786054984Selection of an appropriate crack sealant is essential if the crack sealing operation is to be effective. A high-quality sealant should exhibit the following:
Good bonding (adhesion characteristics)
4088034206148Figure SEQ Figure * ARABIC 3: Applying sealant using wandFigure SEQ Figure * ARABIC 3: Applying sealant using wandEase of application
Resistance to softening
Resistance to tracking
Adequate pot life at application temperatures
Resistance to weathering
Compatibility with asphalt pavement
In many areas, cutback asphalt, emulsified asphalt and lean sand asphalt have been used for crack sealing. These materials have yielded mixed results but generally provided a short service life. In response to a need for better asphalt crack sealant, numerous proprietary sealing materials have been developed. Most of these products can be classified as some form of rubberized asphalt. These rubberized asphalt materials are relatively expensive but are more effective with an expected service life of 3 to 5 years. The asphalt sealant is applied using an applicator wand attached to a sealant machine. The use of a wand ensures that proper application temperature is maintained and eliminate additional handling of the material. Pour pots are not used nowadays because usually the sealant may cool quickly in the pot and need to be reheated, this is more critical during the winter application. The crack should be filled to a level equal to the surface of the pavement and not overfilled because this creates a buildup of material on the surface which causes a poor ride quality. For cracks wider than one inch in width, conventional crack sealing procedures may not suffice.
1.1.7 Squeegee cracks38817552063750Figure SEQ Figure * ARABIC 4: Squeegee operationFigure SEQ Figure * ARABIC 4: Squeegee operation38818875307The squeegee operation level and smooths out any excess sealant, it results in a thin film of sealant across the pavement that aids in sealing the crack. This operation usually follows immediately behind the applicator within usually five feet. This is important because the material cools quickly and is difficult squeegee once it cools. Once the sealant has cooled the road is ready to be opened to traffic, the time required is approximately 15 minutes.
1.2 Crack Repair with Sealing (Saw and Seal)
This treatment method used to reduce or prevent water and silt material from entering a crack as well. This method involves cleaning the crack and make transverse joints evenly spaced along a newly placed pavement (48 hours post paving at the very least) then an asphalt sealant is poured into the cracks. The purpose of this method is to controls shrinkage cracks due to thermal changes, and it is a very effective method to increase the life of the pavement. However, this method is effective for a short period of time. Pavements on granular soils may benefit from having the joints spaced at 9 meters. When longitudinal cracks are sealed, especially on curves, tires may slip when traveling over the over band material. This can be very dangerous and should be considered when sealing longitudinal cracks on curve. Saw & seal usually makes the pavement last for 7 to 10 years when is done properly.
1.2.1 Procedure for saw & sealCrack analysis and identification
Use particular case single pass of a saw to create the reservoir
use air compressor to clean the cracks
Apply asphalt sealant
1.2.2 Properties of the sealant:
According to American Society for Testing and Materials(ASTM) standard D-3405 which is (Standard specification for Joint Sealants, Hot-Poured, for concrete and asphalt pavements) is one of the widely used joint sealant specifications
1.2.3 Determining the Percentage of Success of Saw and SealPercentage of success of this method is determined by how good the process controls the formation of pavement cracks, not by how good the sealant sticks to sawed joints edges. The main objective is to make sure that most of the pavement crack will occur at the sawed joints. Furthermore, the percentage can now be calculated by counting the number of sawed joints and divide it by the summation of sawed joints plus the number of transverse cracks then.
Percentage of Success of Saw and Seal = Sawed JointsSawed Joints + Transverse Cracks*100For example: The following figure illustrates two different pavement test samples:
Figure SEQ Figure * ARABIC 5: Test sample with transverse cracks and sawed joints
From figure 5 above, 3 cracks and 4 joints can be observed. Using the previous equation, we get:
Percentage of Success of Saw and Seal = 4 4 +3*100=57%This percent means that the test section is 57% successful in controlling the cracking.
1.3 Crack Repair with Sealing (Rout and Seal)Rout and seal is one of the most common effective solutions for the transverse and longitudinal cracks. This treatment is highly effective when used for new pavement. The method revolves around creating a reservoir that is centered over the crack on the pavement, then the reservoir is filled with sealant. The purpose of this treatment is to prevent water from going into the pavement. Rout & seal prolongs the pavement life cycle by two to five years.
1.3.1 Procedure for Rout & SealCrack analysis and identification
Use a router to make a reservoir on the crack
Use air compressor to blow out the debris from the reservoir
Fill the reservoir with sealant
1.3.2 Dimensions of the reservoir36480751912620Figure SEQ Figure * ARABIC 6:Reservoir DimensionsFigure SEQ Figure * ARABIC 6:Reservoir Dimensions4562475762000The dimensions of the reservoir are classified by shape factor, which is the ratio of the reservoir width to depth. The higher the shape factor, the less stress the sealant is subjected to as the pavement expands and contracts. The most common shapes for reservoirs are rectangular with dimensions: 19.05 mm by 19.05 mm or 25.4 mm by 25.4mm (a shape factor of 1). The size may be adjusted depending on the sealant properties. Period live on the pavement between 2 to 5 years more.
Pavement rout technique is used to dig a lake at the center of the crack, which is filled with a sealant which will prevent water penetration of the pavement.
2. Crack Filling37947604453255Figure SEQ Figure * ARABIC 7: Longitudinal CrackingFigure SEQ Figure * ARABIC 7: Longitudinal Cracking3794784276850400Crack filling uses differs from crack sealing uses in two main areas: the preparation process for the crack before treatment and the type of crack available for treatment. There are some cracks that can be filled personally and does not require a professional engineer, while other cracks do require a professional engineer. If the crack in the pavement is greater than 0.75-inch-wide, crack sealing will not be an appropriate option. However, sawing on the crack provides enough room for crack filler material and this will give a good control of the repair process. In addition, Crack filling is not going to completely seal the water out of the cracks. However, crack filling does help to minimize the growth of cracks, prevent the formation of new cracks, and reduce the amount of water and other materials that would penetrate the pavement surfaces that cause pavement failure, depending on the amount and size of cracks on the road. Plus, crack filling can be done by using either hot or cold pour materials. filler material is quick to harden and for best results, most crack-filling processes are repeated once a year. Crack filling is usually used for longitudinal cracks. This type of crack is parallel to the surface of pavement at the centerline or laydown direction and it can be a type of either top-down cracking or fatigue cracking.
2.1 Crack Filling ProcedureClean the crack thoroughly to blow out vegetations that fills the gaps of the crack like small grass found on the edges of the crack.
Use a Billy-goat blower or handheld blower for residential use.
Power wash the crack to get rid of any dirt by using Power-Wash Truck.
Let the crack thoroughly dry for couple of hours.
Inject the crack with hot rubber band or by using a good quality crack filler product.
Use the flat blade to level the injected crack filler with the surface of asphalt.
Leave it for 24 hours to cure
2.2 Crack Filling vs SealingAfter acknowledging the previous material, one may ask: To fill or to seal a crack?
Both alternatives depend on two main categories of cracks that are related to the movement of pavement, which is either a “Working” or “Non-working” crack. Crack filling is for non-working cracks that is less than 0.12 inches of annual movement. While, the crack sealing is for cracks that are more than 0.5 inches of annual movement. Moreover, both are for horizontal and vertical movements, but crack filling also includes the longitudinal, diagonal and alligator movements in cracks.
Table SEQ Table * ARABIC 1: Filling vs Sealing Treatment ComparisonCrack Description Crack Treatment Type
Width in inch 0.2 – 0.75 inch 0.2 – 1.0 inch
Annual Movement (horizontally) in inch More than or equal 0.12 inch Less than 0.12 inch
Crack Types Transverse
Thermal / Reflective
Longitudinal Reflective / Cold-Joint Longitudinal Reflective / Cold-Joint / edge
Distantly Spaced Block
3. Full / Partial Depth Repair3.1 Full-Depth Repair It is a rehabilitation method of replacement of weakened concrete pavement as cracks or joints whether it is a small area or an entire path, which helps to restore the structure rideability and integrity of concrete pavement. It is a powerful long-term method to repair asphalt pavement distresses, especially for those that happen close or at joints and break.
3.1.1 FDR ProceduresSurvey
Determination of the repair boundaries by sounding the pavement
Marking 4 inches beyond the repair boundaries.
Saw-cut the specified area.
Remove the crumbled concrete slab. Plus, the damaged base if needed.
Drill holes for longitudinal and transverse tie bars.
Asphalt concrete refilling of excavated area stage 1.
installing “Load-Transfer Device” and placing the tie bars.
Asphalt concrete refilling of excavated area stage 2.
3.2 Partial-Depth Repair Is mostly used for repairing of spalling either at mid-slab location or at pavement joints. Spalling does occur when cracks are filled with incompressible materials, which will prevent the slab movement in hot weather and lead to breakage of the concrete. However, if there are several serious spalls existing at same joint, it might be more economical to use a full-depth repair the entire joint instead of partial-depth repair.
3.2.1 PDR ProceduresDetermination of the repair boundaries.
Placement and Consolidation
Finishing and Curing
3.3 FDR/PDR Repair Boundaries DeterminationRepair boundaries is determined based on the field survey that utilize a data from another survey was done for previous project. In addition, this survey must be conducted as close as possible to the agreement plan schedule. every distressed area must be examined and marking the repair boundaries on the asphalt surface. Plus, all the additional spaces of distress that have occurred since the first survey should be included as well. Moreover, if the partial-depth repairs were mentioned in project plans, a special provision should be included in the project specifications that provides the engineer the freedom to switch from partial-depth to full-depth repairs. Partial-depth repairs are specifically appropriate only for spalls within 1/3 or 1/2 maximum top of the slab. The following table illustrates FDR & PDR comparison:
Table SEQ Table * ARABIC 2: FDR/PDR ComparisonFull Depth Partial Depth
Type of Spall Damage Any damages extended to full slab thickness Any damages extended to the 1/3 – 1/2 max. top of the slab
Applies to Blow Ups corners
Deteriorated Joints/cracks Deteriorated Joints
Economic and Performance More economic and better performance Less economic and low performance
In conclusion, three pavement crack treatment types were studied in this project: Crack sealing, crack filling and full depth crack repair. Crack treatment is of great importance since it protects the base and subbase from further deterioration and prevents structural damage. Crack treatment also provides a better ride quality for vehicles on the road. However, only by following the procedure correctly and performing the treatments properly, the benefits are achieved to the pavement or the traveling public.
References”Asphalt Crack Repair Treatments: Crack Sealing Vs. Crack Filling” (NOV-21-2016) http://kleencoconstruction.com/news/asphalt-crack-repair-treatments-crack-sealing-vs-crack-filling/
G. Dubey (Sep-20-2012) “Know the Difference Between Crack Filling and Crack Sealing” http://callape.com/issue/october-2012/article/know-the-difference-between-crack-filling-and-crack-sealing
“Asphalt Crack Filling” (n.d.). http://www.alsasphalt.com/asphalt-crack-filling.html
“Full/Partial Depth Repair” (n.d.). http://www.interstateimprovement.com/full-partial-depth-repair.html
“Best practices handbook on ASPHALT PAVEMENT MAINTENANCE” http://www.cee.mtu.edu/~balkire/CE5403/AsphaltPaveMaint.pdf”RECLAMATION, Guide To Concrete Repair Second Edition” (2015) https://www.usbr.gov/tsc/techreferences/mands/mands-pdfs/Guide2ConcreteRepair2015_Final.pdf https://aegisasphalt.com/difference-crack-filling-crack-sealing/”Sawing and Sealing Joints in Bituminous Pavements to Control Cracking”http://www.sealnoseal.org/PDF/Asphalt/MNReportSawandSeal.pdf