Meaning Of Cracking The Flags

Contents.This chapter is intended as a general guideline, for which fixes are appropriate for the various distresses on Michigan’s pavements. Although many of the fixes listed have been successful, they may not apply in all cases. Determining the treatment to use in rehabilitating a particular segment of highway is primarily a matter of engineering judgment. Progress has been made in quantifying certain intangibles, matching structural numbers with proposed traffic volumes and calculating cost/benefit analyses, but the major factor remains - engineering judgment.The contents of this chapter include information, text, diagrams and guidance documentation referenced from the US Department of Transportation Federal Highway Administration Manual named, 'Distress Identification Manual for the Long-Term Pavement Performance Program (Publication No. FHWA-RD-03-031, June 2003)'.Michigan has three pavement types; flexible, rigid and composite.

• Meaning Of Cracking The Flags Of The United States

Flexible pavements are constructed using hot mix asphalt (HMA) mixtures, which are typically placed on a combination of granular and dense graded aggregate bases.Rigid pavements are constructed using concrete mixtures, which are commonly placed on a combination of dense graded aggregate bases and granular bases or on open graded aggregate bases and granular bases. Rigid pavements have unique qualities.

The concrete may be plain or reinforced with steel wire fabric reinforcement. Additionally, rigid pavement is poured with joints to allow for contraction and expansion of the concrete. Joint spacing can vary from trunkline to trunkline.Composite pavements are HMA mixtures placed on a rigid pavement.The following provides examples of common distresses and potential fixes for pavements with various type of distresses. It should be noted that some of the fixes can address the distress itself while others will address the pavement as a whole.

In most cases, it is assumed that the distress is prevalent throughout the pavement section and not an isolated location. All of the types of distresses in a given section of pavement will need to be considered when choosing a fix.Primary types of distress associated with flexible pavements are transverse cracking, longitudinal cracking, block cracking, fatigue or alligator cracking, rutting, raveling, shoving and flushing. A description and cause of each, with possible fixes are as follows:DescriptionTransverse cracks are predominantly perpendicular to the pavement centerline. The shape of the rut can be an indicator of the cause. Rutting due to HMA mix instability will have gently sloping sides and a rounded bottom. The HMA may also be 'humped up' next to the rut. Rutting due to poor support will have sides that drop abruptly and a flatter bottom.Possible Fix Options:.

For rutting due to HMA mix instability, a mill and resurface of affected layers will typically address the problem. For rutting due to poor support, a reconstruct is recommended, although a mill and resurface can temporarily restore the pavement to a smooth surface. Other options include microsurface with rut fill preparation and crush and shape.DescriptionRaveling is the wearing away of the pavement surface, caused by the dislodging of aggregate particles and loss of asphalt binder. Raveling ranges from the loss of fines to the loss of some coarse aggregate and ultimately to a very rough and pitted surface with obvious loss of aggregate.Possible Fix Options:.

Low to medium raveling (surface texture is low to moderately rough and pitted) can be addressed with a surface seal. High amount of raveling (surface texture is severely rough and pitted) can be addressed with cold milling and resurfacing.DescriptionShoving is a longitudinal displacement of a localized area of the pavement surface. It is generally caused by braking or accelerating vehicles, and is usually located on hills, curves or intersections. It also may have associated vertical displacement.Possible Fix Options:.

Cold milling and resurfacing with either a high stress HMA mixture or concrete white topping.DescriptionFlushing is the excess of bituminous binder, occurring on the pavement surface, usually found in the wheel paths. It may range from a surface discolored relative to the remainder of the pavement, to a surface that is losing surface texture because of excess asphalt, to a condition where the aggregate may be obscured by excess asphalt possibly with a shiny, glass-like, reflective surface that may be tacky to the touch.Possible Fix Options:. Chip Seal. Microsurface. HMA Overlay (ultra-thin or one-course). Mill and ResurfaceDescriptionPumping is the seeping or ejection of water from beneath the pavement through cracks. In some cases, detectable by deposits of fine material left on the pavement surface, which were eroded (pumped) from the support layers and have stained the surface.Possible Fix Options:.

Joint/Crack Sealing. Full Depth Repair/Replace.

Underdrain RetrofitThis section describes distresses in Jointed Plain Concrete Pavement (JPCP) and Jointed Reinforced Concrete Pavement (JRCP). Since most Continuously Reinforced Concrete Pavement (CRCP) in Michigan has been removed or resurfaced, it will not be discussed in this section. If a CRCP is in need of repair, consult with the Construction and Technology Division for recommendations.Typical distresses in JPCP and JRCP pavements are transverse cracking, longitudinal cracking, joint faulting, joint spalling, mid-slab spalling, joint seal failure and pumping.DescriptionTransverse cracking is predominantly perpendicular to the pavement centerline. In rigid pavement, these are often caused by a combination of heavy load repetition, thermal and moisture gradient stresses and drying shrinkage stresses. Severity LevelsLow Severity Description: Crack widths. Severity LevelsLow Severity Description: Crack widths. Severity LevelsLow Severity Description: Average faulting is ¼ inch and ½ inch.Possible Fix Options:.

Jacking. Full Depth Repair. Overlay. ReconstructDescriptionJoint Spalling occurs in rigid pavement only and is the cracking, breaking, chipping or fraying of slab edges along the face of a longitudinal or transverse joint.

A joint spall usually does not extend vertically through the whole slab thickness, but intersects the joint at an angle. Joint Spalling usually results from excessive stresses at the joint caused by infiltration of incompressible materials and subsequent expansion, freezing and thawing water, or by traffic loading. DescriptionReflective cracking at joints is unique to HMA over concrete pavements and includes all longitudinal and transverse cracks that appear on top of the concrete joints. Knowledge of the slab dimensions beneath the HMA surface will help identify these cracks. These cracks are caused by movements in the concrete slab beneath the HMA surface because of thermal and/or moisture changes. It is generally not load initiated distress.

However, traffic loading may accelerate the deterioration of the cracks and may cause a breakdown of the HMA surface near the initial crack, resulting in spalling.For severity levels and recommended fix options, see transverse cracking for flexible pavements (page 5-4).Distresses and recommended fixes for concrete over HMA are the same as those for rigid pavements (pages 5-13 to 5-23) with the exception that dowel bar retrofit is not recommended. This is due to the fact that concrete over HMA overlays are usually much thinner than 8 inches. It should also be noted that full-depth repairs are much more difficult in concrete overlays due to the bond between the concrete and HMA.In each year’s Integrated Call For Projects (CFP) Letter of Instructions a current Road Rehabilitation and Reconstruction Fix Life Guideline table is provided. Has an example of this table.The tables in show Recommended Corridor Pavement Management Strategies. These tables show possible work types for various pavements, based on existing pavement type, age of pavement and Commercial Average Daily Traffic (CADT) volumes.

The following table uses PASER ratings (as described in ) to categorize HMA pavements and recommend possible fix alternatives.Table 5-4: PASER HMA Rating System10 ExcellentNoneNew construction.9 ExcellentNoneRecent overlay. Like new.8 Very GoodNo longitudinal cracks except reflection of paving joints. Occasional transverse cracks, widely spaced (40’ or greater). All cracks sealed or tight (open less than ¼”).Recent seal coat or new cold mix.

Little or no maintenance required.7 GoodVery slight or no raveling, surface shows some traffic wear. Longitudinal cracks (open ¼”) due to reflection or paving joints. Transverse cracks (open ¼”) spaced 10’ or more apart, little or slight crack raveling. No patching or very few patches in excellent condition.First signs of aging. Maintain with routine crack filling.6 GoodSlight raveling (loss of fines) and traffic wear.

Longitudinal cracks (open ¼”– ½”), some spaced less than 10’. First sign of block cracking. Sight to moderate flushing or polishing. Occasional patching in good condition.Shows signs of aging. Sound structural condition. Could extend life with sealcoat.5 FairModerate to severe raveling (loss of fine and coarse aggregate).

Longitudinal and transverse cracks (open ½”) show first signs of slight raveling and secondary cracks. First signs of longitudinal cracks near pavement edge. Block cracking up to 50% of surface. Extensive to severe flushing or polishing. Some patching or edge wedging in good condition.Surface aging. Sound structural condition.

Needs sealcoat or thin non-structural overlay (less than 2”).4 FairSevere surface raveling. Multiple longitudinal and transverse cracking with slight raveling. Longitudinal cracking in wheel path. Block cracking (over 50% of surface). Patching in fair condition. Slight rutting or distortions (½” deep or less).Significant aging and first signs of need for strengthening.

Would benefit from a structural overlay (2” or more).3 PoorClosely spaced longitudinal and transverse cracks often showing raveling and crack erosion. Severe block cracking. Some alligator cracking (less than 25% of surface). Patches in fair to poor condition. Moderate rutting or distortion (1” or 2” deep).

Meaning Of Cracking The Flags Of The United States

Occasional potholes.Needs patching and repair prior to major overlay. Milling and removal of deterioration extends the life of overlay.2 Very PoorAlligator cracking (over 25% of surface). Severe distortions (over 2” deep) Extensive patching in poor condition. Potholes.Severe deterioration. Needs reconstruction with extensive base repair. Pulverization of old pavement is effective.1 FailedSevere distress with extensive loss of surface integrity.Failed.

Needs total reconstruction. Individual pavements will not have all of the types of distress listed for any particular rating. They may have only one or two types.The following table uses PASER ratings (as described in ) to categorize concrete pavements and recommend possible fix alternatives.Table 5-4: PASER Concrete Pavement Rating System10 ExcellentNoneNew pavement. No maintenance required.9 ExcellentTraffic wear in the wheel path. Slight map cracking or pop-outs.Recent concrete overlay or joint rehabilitation. Like new condition. No maintenance required.8 Very GoodPop-outs, map cracking, or minor surface defects.

Slight surface scaling. Partial loss of joint sealant. Isolated meander cracks, tight or well sealed. Isolated cracks at manholes, tight or well sealed.More surface wear or slight defects. Little or no maintenance required.7 GoodMore extensive surface scaling. Some open joints.

Isolated transverse or longitudinal cracks, tight or well sealed. Some manhole displacement and cracking. First utility patch, in good condition. First noticeable settlement or heave area.First sign of transverse cracks (all tight); first utility patch. More extensive surface scaling. Seal open joints and other routine maintenance.6 GoodModerate scaling in several locations.

A few isolated surface spalls. Shallow reinforcement causing cracks.

Several corner cracks, tight or well sealed. Open (¼” wide) longitudinal or transverse joints and more frequent transverse cracks (some open ¼”).First signs of shallow reinforcement or corner cracking. Needs general joint and crack sealing. Scaled areas could be overlaid.5 FairModerate to severe polishing or scaling over 25% of the surface. High reinforcing steel causing surface spalling.

Some joints and cracks have begun spalling. First signs of joint or crack faulting (¼”). Multiple corner cracks with broken pieces. Moderate settlement or frost heave areas. Patching showing distress.First signs of joint or crack spalling or faulting.

Grind to repair surface defects. Some partial depth patching or joint repairs needed.4 FairSevere polishing, scaling, map cracking, or spalling over 50% of the area.

Joints and cracks show moderate to severe spalling. Pumping and faulting of joints (½”) with fair ride. Several slabs have multiple transverse or meander cracks with moderate spalling.

Spalled area broken into several pieces. Corner cracks with missing pieces or patches. Pavement blowups.Needs some full depth repairs, grinding, and/or asphalt overlay to correct surface defects.3 PoorMost joints and cracks are open, with multiple parallel cracks, severe spalling, or faulting. Dcracking is evident. Severe faulting (1”) giving poor ride. Extensive patching in fair to poor condition.

Many transverse and meander cracks, open and severely spalled.Needs extensive full depth patching plus some full slab replacement.2 Very PoorExtensive slab cracking, severely spalled and patched. Joints failed. Patching in very poor condition. Severe and extensive settlements or frost heaves.Recycle and/or rebuild pavement.1 FailedRestricted speed. Extensive potholes.

Almost total loss of pavement integrity.Total reconstruction.Refer to Appendix A and for guidelines for CPM fixes based on pavement type, Distress Index (DI), Ride Quality Index (RQI), International Roughness Index (IRI) and rutting.Projects that have been selected for CPM funding do not require a crash history analysis, except for HMA resurfacing projects. On those projects, the regions will be required to accurately report superelevation measurements for curves that have a history of crashes. A correlation of crashes to deficient geometry may require a modification of superelevation.The following criteria apply, to all CPM projects:. A gravel shoulder shall require paved shoulder ribbons that are at least three feet wide. The regions are to conduct roadside hardware inspections to determine the amount of guardrail that has severe post and guardrail deterioration. The region will determine whether the guardrail should be upgraded on the capital preventive maintenance project or delayed until a future project.

Replacement of deficient guardrail on freeways should be coordinated through the Region Development Engineer and the Lansing Traffic and Safety Division. Cable-Type guardrail (not Cable Median Barrier) shall be upgraded to current standards or appropriate slope modifications. Blunt and turned down guardrail endings shall be replaced with an appropriate ending from the Road and Bridge Standard Plans. Guardrails shall be connected to bridge rails and piers. The pavement markings, advance warning signs and crossbucks for all railroad crossings shall be upgraded to meet current standards.

However, railroad crossbucks with active signals or gates do not require upgrading by the capital preventive maintenance program. The railroad company is responsible for replacing signals and gates with prioritization independent of the roadway projects.In each year’s Integrated Call For Projects (CFP) Letter of Instructions a CPM Fix Life Extension table is provided for use in that year’s CFP. Below is an example of this table (FY 2007).

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