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53 The following information comes from Asphalt Surfaced Airfields: PAVER⢠Distress Manual (U.S. Army Corps of Engineers 2009). Contents Distress Type Page Joint Seal Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Spalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Longitudinal, Transverse, and Diagonal (L/T/D) Cracks (Mid-Panel Crack) . . . . . . . . . . . . . . 60 Corner Break . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Shattered Slab/Intersecting Cracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Patching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Settlement or Faulting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Concrete Distress Types and Descriptions A P P E N D I X B
54 Pavement Maintenance Guidelines for General Aviation Airport Management Joint Problems Joint Seal Damage Description Any condition that enables soil or rocks to accumulate in the joints or allows significant infiltration of water. Accumulation of incompressible materials prevents the slabs from expanding and may result in buckling, shattering, or spalling. A pliable joint filler bonded to the edges of the slabs protects the joints from accumulation of materials and also prevents water from seeping down and softening the foundation supporting the slab. Typical types of joint seal damage are: (1) stripping of joint sealant, (2) extrusion of joint sealant, (3) weed growth, (4) hardening of the filler (oxidation), (5) loss of bond to the slab edges, and (6) lack or absence of sealant in the joint. How to Count Not counted on a slab-by-slab basis but is rated based on the overall condition of the sealant in the sample unit. In satisfactory condition if it prevents entry of water into the joint, it has some elasticity, and if there is no vegetation growing between the sealer and joint face. Premolded sealer is rated using the same criteria as above except as follows: (1) premolded sealer must be elastic and must be firmly pressed against the joint walls; and (2) premolded sealer must be below the joint edge. If it extends above the surface, it can be caught by moving equipment such as snow plows or brooms and be pulled out of the joint. Premolded sealer is recorded at low severity if any part is visible above joint edge. It is at medium severity if 10% or more of the length is above joint edge or if any part is more than ½ in. (12 mm) above joint edge. It is at high severity if 20% or more is above joint edge or if any part is more than 1 in. (25 mm) above joint edge, or if 10% or more is missing. Rate joint sealer by joint segment. Sample unit rating is the same as the most severe rating held by at least 20% of segments rated. Rate only the left and upstation joints along sample unit boundaries. In rating oxidation, do not rate on appearance. Rate on resilience. Some joint sealer will have a very dull surface and may even show surface cracks in the oxidized layer. If the sealer is performing satisfactorily and has good characteristics beneath the surface, it is satisfactory.
Concrete Distress Types and Descriptions 55 Low Medium High Severity Levels Joint sealer is in generally good condition throughout the sample. Sealant is performing well with only a minor amount of any of the above types of damage present. Joint seal damage is at low severity if a few of the joints have sealer that has debonded from, but is still in contact with, the joint edge. This condition exists if a knife blade can be inserted between sealer and joint face without resistance. Joint sealer is in generally fair condition over the entire surveyed sample with one or more of the above types of damage occurring to a moderate degree. Sealant needs replacement within 2 years. Joint seal damage is at medium severity if a few of the joints have any of the following conditions: (1) joint sealer is in place but water access is possible through visible openings no more than â in. (3 mm) wide; if a knife blade cannot be inserted easily between sealer and joint face, this condition does not exist; (2) pumping debris are evident at the joint; (3) joint sealer is oxidized and lifeless but pliable (like a rope) and generally fills the joint opening; or (4) vegetation in the joint is obvious but does not obscure the joint opening. Joint sealer is in generally poor condition over the entire surveyed sample with one or more of the above types of damage occurring to a severe degree. Sealant needs immediate replacement. Joint seal damage is at high severity if 10% or more of the joint sealer exceeds limiting criteria listed above or if 10% or more of sealer is missing. Joint Seal Damage Severity Levels Good Condition (5 Years Old)
56 Pavement Maintenance Guidelines for General Aviation Airport Management Joint Seal Damage Severity Levels Low Medium High
Concrete Distress Types and Descriptions 57 Spalling For the purposes of this tool, the two types of spalling (transverse/longitudinal joint and corner) are combined. Transverse and Longitudinal Joint Description Breakdown of the slab edges within 2 ft (0.6 m) of the side of the joint. Usually does not extend vertically through the slab but intersects the joint at an angle. Results from excessive stresses at the joint or crack caused by infiltration of incompressible materials or traffic load. Weak concrete at the joint (caused by overworking) combined with traffic loads is another cause of spalling. Note: Frayed condition indicates material is no longer in place along a joint or crack. Spalling indicates material may or may not be missing along a joint or crack. How to Count If the joint spall is located along the edge of one slab, it is counted as one slab with joint spalling. If spalling is located on more than one edge of the same slab, the edge having the highest severity is counted and recorded as one slab. Joint spalling can also occur along the edges of two adjacent slabs. If this is the case, each slab is counted as having joint spalling. If a joint spall is small enough, less than 3 in. (76 mm) wide, to be filled during a joint seal repair, it should not be recorded. Note: If less than 2 ft (0.6 m) of the joint is lightly frayed, the spall should not be counted. Low Medium High Severity Levels Spall over 2 ft (0.6 m) long: (1) spall is broken into no more than three pieces defined by low- or medium- severity cracks; little or no FOD potential exists; or (2) joint is lightly frayed; little or no FOD potential. Spall less than 2 ft long is broken into pieces or fragmented with little FOD or tire damage potential exists. Lightly frayed means the upper edge of the joint is broken away leaving a spall no wider than 1 in. (25 mm) and no deeper than ½ in. (13 mm). The material is missing and the joint creates little or no FOD potential. Spall over 2 ft (0.6 m) long: (1) spall is broken into more than three pieces defined by light or medium cracks; (2) spall is broken into no more than three pieces with one or more of the cracks being severe with some FOD potential existing; or (3) joint is moderately frayed with some FOD potential. Spall less than 2 ft long: spall is broken into pieces or fragmented with some of the pieces loose or absent, causing considerable FOD or tire damage potential. Moderately frayed means the upper edge of the joint is broken away leaving a spall wider than 1 in. (25 mm) or deeper than ½ in. (13 mm). The material is mostly missing, with some FOD potential. Spall over 2 ft (0.6 m) long: (1) spall is broken into more than three pieces defined by one or more high-severity cracks with high FOD potential and high possibility of the pieces becoming dislodged, or (2) joint is severely frayed with high FOD potential.
58 Pavement Maintenance Guidelines for General Aviation Airport Management Corner Description Raveling or breakdown of the slab within approximately 2 ft (0.6 m) of the corner. Differs from a corner break in that the spall usually angles downward to intersect the joint, while a break extends vertically through the slab. How to Count If one or more corner spalls having the same severity level are located in a slab, the slab is counted as one slab with corner spalling. If more than one severity level occurs, it is counted as one slab having the higher severity level. A corner spall smaller than 3 in. (76 mm) wide, measured from the edge of the slab, and filled with sealant is not recorded. Low Medium High Severity Levels One of the following conditions exists: (1) spall is broken into one or two pieces defined by low-severity cracks (little or no FOD potential); or (2) spall is defined by one medium- severity crack (little or no FOD potential). One of the following conditions exists: (1) spall is broken into two or more pieces defined by medium-severity cracks, and a few small fragments may be absent or loose; (2) spall is defined by one severe, fragmented crack that may be accompanied by a few hairline cracks; or (3) spall has deteriorated to the point where loose material is causing some FOD potential. One of the following conditions exists: (1) spall is broken into two or more pieces defined by high-severity fragmented cracks with loose or absent fragments; (2) pieces of the spall have been displaced to the extent that a tire damage hazard exists; or (3) spall has deteriorated to the point where loose material is causing high FOD potential.
Concrete Distress Types and Descriptions 59 Spalling (Corner) Severity Levels Low Medium High
60 Pavement Maintenance Guidelines for General Aviation Airport Management Cracking Longitudinal, Transverse, and Diagonal (L/T/D) Cracks (Mid-Panel Crack) Description These cracks, which divide the slab into two or three pieces, are usually caused by a combination of load repetition, curling stresses, and shrinkage stresses (for slabs divided into four or more pieces). Low-severity cracks are usually warping- or friction-related and are not considered major structural distresses. Medium- or high-severity cracks are usually working cracks and are considered major structural distresses. Note: Hairline cracks that are only a few feet long and do not extend across the entire slab are rated as shrinkage cracks. How to Count Once the severity has been identified, the distress is recorded as one slab. If the slab is divided into four or more pieces by cracks, refer to the distress type âshattered slab.â Cracks used to define and rate corner breaks, âDâ cracks, patches, shrinkage cracks, and spalls are not recorded as L/T/D cracks. Low Medium High Severity Levels Crack has little or minor spalling (no FOD potential). If non-filled, it has a mean width of less than approximately â in. (3 mm). A filled crack can be of any width, but the filler material must be in satisfactory condition; or the slab is divided into three pieces by low- severity cracks. One of the following conditions exists: (1) a filled or non-filled crack is moderately spalled (some FOD potential); (2) a non- filled crack has a mean width of between â and 1 in. (3 and 25 mm); (3) a filled crack is not spalled or only lightly spalled, but the filler is in unsatisfactory condition; or (4) the slab is divided into three pieces by two or more cracks, one of which is of at least medium severity. One of the following conditions exists: (1) a filled or non-filled crack is severely spalled, causing definite FOD potential; (2) a non-filled crack has a mean width of greater than approximately 1 in. (25 mm), creating a tire damage potential; or (3) the slab is divided into three pieces by two or more cracks, one of which is of at least high severity.
Concrete Distress Types and Descriptions 61 Longitudinal, Transverse, and Diagonal (Mid-Panel) Crack Severity Levels (20% or 40% Slabs) Low Medium High
62 Pavement Maintenance Guidelines for General Aviation Airport Management Corner Break Description A crack that intersects the joints at a distance of less than or equal to one-half of the slab length on both sides, measured from the corner of the slab. For example, a slab with dimensions of 25 ft by 25 ft (7.5 by 7.5 m) that has a crack intersecting the joint 5 ft (1.5 m) from the corner on one side and 17 ft (5 m) on the other side is not considered a corner break; it is a diagonal crack. However, a crack that intersects 7 ft (2 m) on one side and 10 ft (3 m) on the other is considered a corner break. Differs from a corner spall in that the crack extends vertically through the entire slab thickness, while a corner spall intersects the joint at an angle. Load repetition combined with loss of support and curling stresses usually cause corner breaks. How to Count Recorded as one slab if it contains a single corner break, contains more than one break of a particular severity, or contains two or more breaks of different severities. For two or more breaks, the highest level of severity should be recorded. For example, a slab containing both light- and medium-severity corner breaks should be counted as one slab with a medium corner break. Crack widths should be measured between vertical walls, not in spalled areas of the crack. If the corner break is faulted â in. (3 mm) or more, increase severity to the next higher level. If the corner is faulted more than ½ in. (13 mm), rate the corner break at high severity. If faulting in corner is incidental to faulting in the slab, rate faulting separately. The angle of crack into the slab is usually not evident at low severity. Unless the crack angle can be determined, to differentiate between the corner break and corner spall, use the following criteria. If the crack intersects both joints more than 2 ft (600 mm) from the corner, it is a corner break. If it is less than 2 ft, unless you can verify the crack is vertical, call it a spall. Low Medium High Severity Levels Crack has little or minor spalling (no FOD potential). If non-filled, it has a mean width of less than approximately â in. (3 mm). A filled crack can be of any width, but the filler material must be in satisfactory condition. The area between the corner break and the joints is not cracked. One of the following conditions exists: (1) filled or non-filled crack is moderately spalled (some FOD potential); (2) a non-filled crack has a mean width of between â and 1 in. (3 and 25 mm); (3) a filled crack is not spalled or only lightly spalled, but the filler is in unsatisfactory condition; or (4) the area between the corner break and the joints is lightly cracked. Lightly cracked means one low-severity crack dividing the corner into two pieces. One of the following conditions exists: (1) filled or non-filled crack is severely spalled, causing definite FOD potential; (2) a non-filled crack has a mean width of greater than approximately 1 in. (25 mm), creating a tire damage potential; or (3) the area between the corner break and the joints is severely cracked.
Concrete Distress Types and Descriptions 63 Corner Break Severity Levels (10% or 30% Slabs) Low Medium High
64 Pavement Maintenance Guidelines for General Aviation Airport Management Shattered Slab/Intersecting Cracks Description Cracks that break the slab into four or more pieces due to overloading or inadequate support, or both. The high-severity level of this distress type, defined as follows, is referred to as shattered slab. If all pieces or cracks are contained within a corner break, the distress is categorized as a severe corner break. How to Count No other distress (such as scaling, spalling, or durability cracking) should be recorded if the slab is medium- or high-severity level since the severity of this distress would affect the slabâs rating substantially. Shrinkage cracks should not be counted in determining whether or not the slab is broken into four or more pieces. Low Medium High Severity Levels Slab is broken into four or five pieces predominantly defined by low-severity cracks. Slab is broken into four or five pieces with over 15% of the cracks of medium severity (no high-severity cracks); slab is broken into six or more pieces with over 85% of the cracks of low severity. At this level of severity, the slab is called shattered: (1) slab is broken into four or five pieces with some or all cracks of high severity; or (2) slab is broken into six or more pieces with over 15% of the cracks of medium or high severity. Shattered Slab/Intersecting Cracks Severity Levels (10% or 30% Slabs) Low
Concrete Distress Types and Descriptions 65 Shattered Slab/Intersecting Cracks Severity Levels (10% or 30% Slabs) Medium High
66 Pavement Maintenance Guidelines for General Aviation Airport Management Surface Distress Patching Description An area where the original pavement has been removed and replaced by a filler materialâ large (over 5 ft2 [0.5 m2]) or small (less than 5 ft2 [0.5 m2]). The online tool is designed for large patching. How to Count If one or more small patches having the same severity level are located in a slab, it is counted as one slab containing that distress. If more than one severity level occurs, it is counted as one slab with the higher severity level being recorded. Low Medium High Severity Levels Patch is functioning well with very little or no deterioration. Patch deterioration or moderate spalling, or both, can be seen around the edges. Patch material can be dislodged with considerable effort, causing some FOD potential. Patch has deteriorated to a state that causes considerable roughness or high FOD potential, or both. The extent of the deterioration warrants replacement of the patch.
Concrete Distress Types and Descriptions 67 Patching Severity Levels (30% or 50% Slabs) Low Medium High
68 Pavement Maintenance Guidelines for General Aviation Airport Management Settlement or Faulting Description A difference of elevation at a joint or crack caused by upheaval or consolidation. How to Count In counting settlement, a fault between two slabs is counted as one slab. A straightedge or level should be used to aid in measuring the difference in elevation between the two slabs. Construction-induced elevation differential is not rated in PCI procedures. Where construction differential exists, it can often be identified by the way the high side of the joint was rolled down by finishers (usually within 6 in. [150 mm] of the joint) to meet the low-slab elevation. Severity Levels Severity levels are defined by the difference in elevation across the fault and the associated decrease in ride quality and safety as severity increases: Runways/Taxiways Aprons L <¼ in. (6 mm) 1/8 to ½ in. (3 to 13 mm) M ¼ to ½ in. (6 to 13 mm) ½ to 1 in. (13 to 25 mm) H >½ in. (13 mm) >1 in. (25 mm)
Concrete Distress Types and Descriptions 69 Settlement or Faulting Severity Levels (10% or 30% Slabs) Low Medium High
