Infrastructure-Failures of Rigid Pavements

SUBMITTED BY:

RAHUL N.SOMPURA (2905)

SCHOOL OF BUILDING SCIENCE & TECHNOLOGY,

CEPT UNIVERSITY, AHMEDABAD

INFRASTRUCTURE IFAILURES OF RIGID PAVEMENTS

FACULTY INCHARGE: MISS AANAL SHETH

INFRASTRUCTURE – FAILURES IN RIGID PAVEMENTS

RAHUL N. SOMPURA (2905), SCHOOL OF BUILDING SCIENCE & TECHNOLOGY, CEPT UNIVERSITY, AHMEDABAD

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CONTENTS

1 INTRODUCTION..............................................................................4

1.1 NEED FOR HIGHWAY MAINTENANCE..................................... 4

1.2 GENERAL CAUSES OF PAVEMENT FAILURES .......................... 4

1.3 CLASSIFICATION OF MAINTENANCE WORK ........................... 4

2 FAILURES IN RIGID PAVEMENTS.....................................................5

2.1 DEFICIENCY OF PAVEMENT MATERIALS................................. 5

2.2 STRUCTURAL INADEQUACY OF PAVEMENT SYSTEM .............. 6

3 TYPICAL RIGID PAVEMENT FAILURES .............................................6

3.1 SCALING OF CEMENT CONCRETE ........................................... 7

3.2 SHRINKAGE CRACKS............................................................... 7

3.3 SPALLING OF JOINT ............................................................... 7

3.4 WARPING CRACKS ................................................................. 7

3.5 MUD PUMPING ..................................................................... 7

4 MAINTENANCE OF CEMENT CONCRETE ROADS .............................9

4.1 TREATMENT OF CRACKS ........................................................ 9

4.2 MAINTENANCE OF JOINTS ................................................... 10

5 SPECIAL REPAIRS OF CEMENT CONCRETE PAVEMENTS ............... 11

5.1 MUD JACKING OR LIFTING OF SLABS ................................... 11

6 STRENGTHENING OF EXISTING PAVEMENTS ............................... 11

6.1 RIGID OVERLAY OVER RIGID PAVEMENT.............................. 11

6.2 FLEXIBLE OVERLAY OVER RIGID PAVEMENT......................... 12

7 VARIOUS RIGID PAVEMENT FAILURES CASES .............................. 13

7.1 BLOWUP (BUCKLING)........................................................... 13

7.2 CORNER BREAK .................................................................... 14

7.3 DURABILITY CRACKING ("D" CRACKING) .............................. 14

7.4 FAULTING ............................................................................ 15

7.5 JOINT LOAD TRANSFER SYSTEM DETERIORATION................ 15

7.6 LINEAR (PANEL) CRACKING .................................................. 16

7.7 PATCHING............................................................................ 17

7.8 POLISHED AGGREGATE ........................................................ 17



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7.9 POPOUTS............................................................................. 18

7.10 PUNCHOUT.......................................................................... 18

7.11 REACTIVE AGGREGATE DISTRESSES ..................................... 19

7.12 SHRINKAGE CRACKING ........................................................ 19

7.13 SPALLING ............................................................................. 20

8 CONCLUSION …………………………………………………………………………….21

9 REFERENCES …………………………………………………………………………….21



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1 INTRODUCTION

1.1 NEED FOR HIGHWAY MAINTENANCE

Road maintenance is one of the important components of the entire road system. The maintenance operations involve the assessment of road condition, diagnosis of problem and adopting the most appropriate maintenance steps. Even if the highways are well designed and constructed, they may require maintenance; the extent of which will depend on several factors including the pavement type. Various types of failures in pavements ranging from minor and localized failure to major and general failures do take place on roads. The failures may be due to one or a combination of several causes.

1.2 GENERAL CAUSES OF PAVEMENT FAILURES

Some of the general causes of pavement failures needing maintenance measures may be classified as given below;

Defects in the quality of materials used.

Defects In construction method and quality control during construction.

Inadequate surface or subsurface drainage in the locality resulting in the stagnation of water in the subgrade or in any of the pavement layers.

Increase in the magnitude of wheel loads and the number of load repetitions due to increase in traffic volume.

Settlement of foundation of embankment of the fill material itself.

Environmental factors including heavy- rainfall, soil erosion, high water table, snow fall, frost action, etc

1.3 CLASSIFICATION OF MAINTENANCE WORK

The various items of highway maintenance works may he broadly classified under three heads:

Routine maintenance-repairs :These include tilling up of pot holes and patch repairs, maintenance of shoulders and the cross slope, upkeep of the road side drains and clearing choked culverts, maintenance of miscellaneous items like road signs, arboriculture, inspection bungalows, etc.



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Periodic maintenance: These include renewals of wearing course of pavement surface and preventive maintenance of various items.

Special repairs : These include strengthening of pavement structure or overlay construction, reconstruction of pavement, widening of roads, repairs of damages caused by floods, providing additional safety measures like islands, signs etc.

2 FAILURES IN RIGID PAVEMENTS

The cement concrete pavements may develop cracks and deteriorate due to repeated loads and fatigue effects. A rigid pavement failure is observed by the development of structural crack of break resulting in progressive subsidence of some portions of pavement. Moderate irregularities in the supporting layers beneath the cement concrete pavements are sustained due to inherent bending strength of these pavements. Rigid pavements are therefore capable of withstanding slight variations in the underlying support and they bridge the localized gaps moderately. It is the combination of many factors that induce the failure conditions in the rigid pavement. Due to the temperature effects, the newly constructed cement concrete pavements may also crack even if no vehicle moves on them. Often failure of rigid pavements starts from joints, corners and edges of slabs.

Failures of cement concrete pavements are recognized mainly by the formation of structural cracking. The failures are mainly due to two factors:

Deficiency of pavement materials

Structural inadequacy of the pavement system.

2.1 DEFICIENCY OF PAVEMENT MATERIALS

Following are the chief causes which would give rise to the different defects or failures of cement concrete pavement:

Soft aggregates

Poor workmanship in joint construction

Poor joint filler and sealer material

Poor Surface finish

Improper and insufficient curing

The various defects that creep in due to the above are:

Disintegration of cement concrete

Formation of cracking



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Spalling of joints

Poor riding surface

Slippery surface

Formation of shrinkage cracks

Ingress of surface water and further progressive failures

2.2 STRUCTURAL INADEQUACY OF PAVEMENT SYSTEM

Inadequate subgrade support pavement thickness would be a major cause of developing structural cracking in pavements. Following arethe causes and types of failure which develop:

Inadequate pavement thickness

Inadequate subgrade support and poor subgrade soil

Incorrect spacing of joints

Above would give rise to the failures of the following types:

Cracking of slab comers

Cracking of pavements longitudinally.

Settlement of slabs

Widening of joints

Mud pumping

3 TYPICAL RIGID PAVEMENT FAILURES

Following are some typical and basic types of failures in rigid pavements which are dealt here in detail:

Scaling of cement concrete

Shrinkage cracks

Spalling of joints

Warping cracks

Mud pumping

Structural cracks



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3.1 SCALING OF CEMENT CONCRETE

Scaling is observed in cement concrete pavement showing overall deterioration of the concrete. The scaling is mainly attributed due to the deficiency in the mix or presence of some chemical impurities which damage the mix. Further due to excessive vibration given to mix, the cement mortar comes to the top during construction and thus with use, the cement mortar gets abraded exposing the aggregate of the mix. This makes the pavement surface rough and shabby in appearance.

3.2 SHRINKAGE CRACKS

During the curing, operation of cement concrete pavements immediately after the construction, the shrinkage cracks normally develops. The placement of cracks arc in longitudinal as well as in transverse direction.

3.3 SPALLING OF JOINT

Sometimes when pre-formed filler materials are placed during casting of pavement slabs, the placement is somehow dislocated and filler is thus placed at an angle. The concreting is completed without noticing this faulty alignment or the filler material. Thus this forms an overhang of a concrete layer on the top side and the joint later on shows excessive cracking and subsidence

3.4 WARPING CRACKS

If the joints are not well designed to accommodate the warping of slabs at edges, this result in development of excessive stresses due to warping and the slab develops cracking at the edges in an irregular pattern. Hinge Joints are generally provided for relieving the slabs of warping stresses. There is no structural defect due to the warpingcracks if proper reinforcement is provided at the longitudinal and transverse joints as it takes care of the structural adequacy.

3.5 MUD PUMPING

Mud pumping is recognized when the soil slurry ejects out through the joints and cracks of cement concrete pavement caused during the downward movement of slab under the heavy wheel loads. Following are the factors which cause the mud pumping:

Extent of slab deflection

Type of sub grade soil

Amount of free water

Pumping is noticed just after the rains in cement concrete pavements that are placed on clayey soil sub grade. Due to the applications of repealed loads, initial spaces are developed underneath the pavementslabs and water infiltrates into these spaces through joints, cracks and edges of the pavements as shown in Fig. 1.a. Since the soil is also of

fine grained type, it holds water and forms the soil slurry or soil suspension in water or the

Subsequent application of heavy wheeslabeach time,Fig. 1.bsubstantial loss in fine grained soil from subconsiderable loss of subcontinued traffic movements, there is progressive increase in the wheel load stress in the pavement slab due to reduction m subsupport, consequently cracks are developed and the pavement ultimately faimud pumping is generally a progressive type of failure in rigid pavements

Inadequate pavement thickness tor the amount and typethe prime reasonare found to crack at tLongitudinal and transversequite difficult to differentiate the type of cracks. Generally, if it could be decided that the crack in the vicinity of jointsdue to spstructural inadequacy. Tdue to the temperature stresses.


fine grained type, it holds water and forms the soil slurry or soil suspension in water or the

Subsequent application of heavy wheeslab to deflect at critical locations and also forces out part of the mud each time, through the spacesFig. 1.b. When mosubstantial loss in fine grained soil from subconsiderable loss of subcontinued traffic movements, there is progressive increase in the wheel load stress in the pavement slab due to reduction m subsupport, consequently cracks are developed and the pavement ultimately fails as illustrated in Fig.1.cmud pumping is generally a progressive type of failure in rigid pavements.

Inadequate pavement thickness tor the amount and typethe prime reasonare found to crack at tLongitudinal and transversequite difficult to differentiate the type of cracks. Generally, if it could be decided that the crack in the vicinity of jointsdue to spalling or mud pumping, then the cracks are attributed structural inadequacy. Tdue to the temperature stresses.


fine grained type, it holds water and forms the soil slurry or soil suspension in water or the mud.

Subsequent application of heavy wheeto deflect at critical locations and also forces out part of the mud

through the spaces in pavement joints, cWhen more and more mud is ejected

substantial loss in fine grained soil from subconsiderable loss of sub grade support at these locations With continued traffic movements, there is progressive increase in the wheel load stress in the pavement slab due to reduction m subsupport, consequently cracks are developed and the pavement

ls as illustrated in Fig.1.cmud pumping is generally a progressive type of failure in rigid

Inadequate pavement thickness tor the amount and typefor the structural cracking. Largely, the p

are found to crack at the comers and edges as shown in Fig.2Longitudinal and transverse cracks are also found to exist.quite difficult to differentiate the type of cracks. Generally, if it could be decided that the crack in the vicinity of joints

g or mud pumping, then the cracks are attributed structural inadequacy. The cracking in the interior regions are mainly due to the temperature stresses.


fine grained type, it holds water and forms the soil slurry or soil

Subsequent application of heavy wheel loads causes the pavement to deflect at critical locations and also forces out part of the mud

pavement joints, cre and more mud is ejected out,

substantial loss in fine grained soil from sub grade, resugrade support at these locations With

continued traffic movements, there is progressive increase in the wheel load stress in the pavement slab due to reduction m subsupport, consequently cracks are developed and the pavement

ls as illustrated in Fig.1.c. The pavement crackmud pumping is generally a progressive type of failure in rigid

Inadequate pavement thickness tor the amount and typefor the structural cracking. Largely, the p

and edges as shown in Fig.2cracks are also found to exist.

quite difficult to differentiate the type of cracks. Generally, if it could be decided that the crack in the vicinity of joints or comers are not

g or mud pumping, then the cracks are attributed he cracking in the interior regions are mainly

INFRASTRUCTURE


fine grained type, it holds water and forms the soil slurry or soil

l loads causes the pavement to deflect at critical locations and also forces out part of the mud

pavement joints, cracks or edge. See out, there is a

grade, resulting in grade support at these locations With

continued traffic movements, there is progressive increase in the wheel load stress in the pavement slab due to reduction m sub grade support, consequently cracks are developed and the pavement

. The pavement cracking due to mud pumping is generally a progressive type of failure in rigid

Inadequate pavement thickness tor the amount and type of vehicles is for the structural cracking. Largely, the pavements

and edges as shown in Fig.2. cracks are also found to exist. It becomes

quite difficult to differentiate the type of cracks. Generally, if it could or comers are not

g or mud pumping, then the cracks are attributed to the he cracking in the interior regions are mainly

INFRASTRUCTURE


l loads causes the pavement to deflect at critical locations and also forces out part of the mud

racks or edge. See

grade

ing due to

of vehicles is avements

It becomes quite difficult to differentiate the type of cracks. Generally, if it could

or comers are not to the

he cracking in the interior regions are mainly



FAILURES IN RIGID PAVEMENTS


Figure 1: MUD PUMPING



: MUD PUMPING





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Figure


Figure 2: FORMATION OF REFLECTION CRACKS


FORMATION OF REFLECTION CRACKS

INFRASTRUCTURE


FORMATION OF REFLECTION CRACKS

INFRASTRUCTURE


4

It may be staled here that very little maintenance suof joints only is desigformation of craand causes are ascertained before

4.1

The cracks developed in cement concrete (CC) may be classified into two groups:

The presence of fine cracks only as such are not harmfucallthe cracks are visible on the top of the slab, the cracks at the bottom



MAINTENANCE OF CEMEN

It may be staled here that very little maintenance suof joints only is needed fodesigned and constructed. Main defectformation of cracks. It is therefore necessary to examine the cracksand causes are ascertained before

TREATMENT OF CRACKS

The cracks developed in cement concrete (CC) may be classified into two groups:

Temperature cracks, hair-cracks formed across the sltransverse or longitudinaltwo or more approximately equal parts due to the temperature stresses like the etc. in the slab.

Structural cracks the slabs, due to combined wheethe slab.

The presence of fine cracks only as such are not harmfufor immediate maintenance. As the cracks due to the shrinkage in

the CC pavement start from the bottomcracks are visible on the top of the slab, the cracks at the bottom



MAINTENANCE OF CEMENT CONCRETE ROADS

It may be staled here that very little maintenance suneeded for cement concrete roads,

ned and constructed. Main defectcks. It is therefore necessary to examine the cracks

and causes are ascertained before any remedial measure is adopted.

TREATMENT OF CRACKS

The cracks developed in cement concrete (CC) may be classified into

Temperature cracks, which are initially fine cracks or cracks formed across the sl

transverse or longitudinal joints, dividing the slab lengthtwo or more approximately equal parts due to the temperature stresses like the etc. in the slab.

Structural cracks formed near the edge and comer regions of the slabs, due to combined whee

The presence of fine cracks only as such are not harmfumaintenance. As the cracks due to the shrinkage in

pavement start from the bottomcracks are visible on the top of the slab, the cracks at the bottom



T CONCRETE ROADS

It may be staled here that very little maintenance such as maintenance r cement concrete roads, if they are well

ned and constructed. Main defect in this type of road is cks. It is therefore necessary to examine the cracks

any remedial measure is adopted.


which are initially fine cracks or cracks formed across the slab, in between a pair of

joints, dividing the slab lengthtwo or more approximately equal parts due to the temperature stresses like the shrinkage stress, warping stress,

formed near the edge and comer regions of the slabs, due to combined wheel load and warping stresses in

The presence of fine cracks only as such are not harmfumaintenance. As the cracks due to the shrinkage in

pavement start from the bottom of the slab, by the time fcracks are visible on the top of the slab, the cracks at the bottom



T CONCRETE ROADS

ch as maintenance if they are well

ype of road is cks. It is therefore necessary to examine the cracks

any remedial measure is adopted.


which are initially fine cracks or ab, in between a pair of

joints, dividing the slab length into two or more approximately equal parts due to the

shrinkage stress, warping stress,

formed near the edge and comer regions of l load and warping stresses in

The presence of fine cracks only as such are not harmful and do not maintenance. As the cracks due to the shrinkage in

of the slab, by the time fine cracks are visible on the top of the slab, the cracks at the bottom



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ch as maintenance

into

shrinkage stress, warping stress,

formed near the edge and comer regions of l load and warping stresses in

maintenance. As the cracks due to the shrinkage in



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portion would have got widened. Due to repeated application of heavy wheel loads and the variations in temperature and moisture conditions, the cracks get widened and further deterioration becomes rapid. Once the surface water starts getting into the pavement and the subgrade through the widened cracks, progressive failure or the pavement is imminent. Therefore before these cracks get wide enough to permit infiltration of water, they should be scaled off to prevent rapid deteriorations.

The dirt, sand and other loose panicles at the cracks are thoroughly cleaned using a sharp tool, stiff brush and pressure blower. Kerosene oil is applied on the cleaned cracks to facilitate proper bonding of the sealing material. The cracks are then filled by suitable grade bituminous sealing compound, heated to liquid consistency. The sealer is placed upto about 3 mm above the level of the slab along the cracks and a layer of sand is spread over it to protect the sealer temporarily.

The formation of structural cracks in CC slabs should be viewed seriously and needs immediate attention, as these indicate possible beginning of pavement failure. First the cause of the failure should be investigated. If the failure is confined to one or a few slab only at a particular location, and in general there are no structural cracks in other slabs, the failure may be localized one due to some weak spot in the subgrade or due to localized settlement of embankment or underground drainage problem. The maintenance work in such a case involves first remedy of the basic cause of the failure and then re-casting the failed slabs. In the case of general pavement distress

indicating the start of structural failure of the pavement, immediate steps are to be taken to strengthen the CC pavement by a flexible or rigid overlay expeditiously before the structural cracks develop in other slabs also. It is not worthwhile to provide an overlay over a badly cracked or failed CC pavement as the riding surface becomes very unsatisfactory due to uneven settlement of the cracked and broken slabs. In such a case the only permanent solution is removal of the broken-up CC pavement slabs and re-construction of new flexible or rigid pavement

4.2 MAINTENANCE OF JOINTS

Joints are the weakest parts in CC pavements .The efficiency of the pavement is determined by the proper functioning of the joints.Majority of the failure in the CC pavements arc observed at or near the joints. Therefore, utmost care is to be taken to see that the filler and sealer materials are intact at the joints. During summer the joint sealer material is squeezed out of the expansion joints due to the expansion of the slabs; subsequently as the slabs contract during winter, the joint gap opens out and cracks are formed in the old sealer material. Therefore, periodic maintenance of the joint sealer is essential both at expansion and contraction joints as a part of routine maintenance work of the CC pavement. The opened-up joints are cleaned with brush and refilled with suitable joint sealer material before the start of the rains.



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The joint filler material at the expansion joints may get damaged or deteriorated after several years of pavement life The repair consist of removal of the sealer and deteriorated filler and sealer materials from the expansion joints cleaning up, replacement with new filler board (provided with suitable grooves cut on the bottom half at the positions of the dowel bars) and sealing the top of the joints with suitable sealer material. It will be convenient to insert the new- filler board at the expansion joints during winter season when the joint opening is widest.

5 SPECIAL REPAIRS OF CEMENT CONCRETE PAVEMENTS

5.1 MUD JACKING OR LIFTING OF SLABS

Once pavement starts pumping, the remedy for correcting it lies in providing the effective drainage. If the subsidence is localized then the same is repaired by patching the portions of slabs with bituminous mixes. Advanced countries adopt the procedures of mud jacking. The process consists of drilling number of holes 4 cm to 5 cm diameter 1.5 metre to 3 metre apart in the cement concrete slab. Grouting in such slabs is done under pressure through these holes. The grout normally used is either 1:3.5 cement-sand mix or bitumen. For cement-sand mix, colloidal mix with sufficient water is prepared. The mix is thus injected through a pressure holes using the compressor. The slabs are thus raised from below by the pressure grout, upto the desired level.

6 STRENGTHENING OF EXISTING PAVEMENTS

6.1 RIGID OVERLAY OVER RIGID PAVEMENT

When a rigid or CC overlay is constructed over an existing rigid or CC pavement, the interface between the old and new concrete cannot have perfect bond such that the two slabs could act as a monolithic one. Two typical types of interface are possible:

Providing maximum possible interface bond by making the old surface rough

Separating the two slabs at the interface by thin layer of bituminous material, or without interface bond

To obtain the overlay thickness, the following relationship may he used:

hO=( hda-Xhe

b)n

Where hO=rigid overlay thickness

hd=design thickness

he=existing pavement thickness



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Values of a, b. X and n depend upon the pavement and the method of overlay construction. Table 1 shows the recommended values of these factors.

AGENCYEXISTING PAVEMENT

CONDITIONX

Crops of Engineers &

PCA

Good condition 1.00

Initial cracking 0.75

Badly cracked 0.35

AGENCY CONSTRUCTION METHOD a b n

Crops of Engineers

Poured directly on old pavement 1.40 1.40 1/1.40

Levelling course 2.20 2.00 1/3.00

PCA

Poured directly on old pavement 1.87 2.00 1/2.00

Levelling course 2.00 2.00 1/2.00

6.2 FLEXIBLE OVERLAY OVER RIGID PAVEMENT

A flexible or bituminous overlay when provided over a rigid pavement, the wheel load is distributed through a larger area by the overlay, thus slightly reducing the wheel load stress on the old rigid pavement. Further the maximum temperature differential in the rigid pavement is also decreased due to the bituminous overlay, thus causing a substantial reduction in the warping stress and also in the maximumcombined stress. Thus a rigid or CC pavement may be strengthened by a bituminous overlay before the pavement develops structural crack and starts failing. The useful life of the rigid pavement may be increased considerably by a suitably designed and constructed bituminous overlay placed at the right time.

For calculating the thickness of flexible overlay over rigid pavements the following relationship is employed.

hf=2.5(F

Where hf = flexible overlay thickness

= existing rigid pavement thickness

= design thickness of rigid pavement

F = factor which depends upon modulus of existing pavement

For calculating the thickness of bituminous overlay, the following relationship is used.

7

7.1

Description:joint or crack.insufficient room for slab expansion during hot weather.



7 VARIOUS RIGID PAVEME

7.1 BLOWUP (BUCKLING)

Description: A localized upward slab movement and shattering at a joint or crack. Usually occurs in spring or summer and is the result of insufficient room for slab expansion during hot weather.

Figure 3: SEVERE BLOW UP



VARIOUS RIGID PAVEMENT FAILURES CASES

BLOWUP (BUCKLING)

A localized upward slab movement and shattering at a Usually occurs in spring or summer and is the result of

insufficient room for slab expansion during hot weather.

: SEVERE BLOW UP


For calculating the thickness of bituminous overlay, the following

NT FAILURES CASES



Figure

INFRASTRUCTURE


For calculating the thickness of bituminous overlay, the following

NT FAILURES CASES



Figure 4:SEVERE BLOW UP

INFRASTRUCTURE



Problem:first

Possible Causes:leaving wider joint openings.incompressible material (such as rocks or soil), subsequent PCC slab expansion during hot periods (e.g., spring, summer) may cause high compressive stresses.may buckle and shatter to reliaccelerated by:

Repair:



Problem: Roughnessfirst photo) can pose a safety hazard

Possible Causes: During cold periods (e.g., winter) PCC slabs contract leaving wider joint openings.incompressible material (such as rocks or soil), subsequent PCC slab expansion during hot periods (e.g., spring, summer) may cause high compressive stresses.may buckle and shatter to reliaccelerated by:

Joint spallingincompressible material to fi

D cracking Freeze-thaw damage (weakens the slab near the joint/crack area)

Repair: Full-depth patch



Roughness, moisture infiltration, inphoto) can pose a safety hazard

During cold periods (e.g., winter) PCC slabs contract leaving wider joint openings. If these openingincompressible material (such as rocks or soil), subsequent PCC slab expansion during hot periods (e.g., spring, summer) may cause high compressive stresses. If these stresses are great enough, the slabs may buckle and shatter to relieve the stresses.

Joint spalling (reduces slab contact area and provides incompressible material to fill the joint/crack)

D cracking (weakens the slab near the joint/crack area)thaw damage (weakens the slab near the joint/crack

depth patch.



, moisture infiltration, in extreme cases (as in the photo) can pose a safety hazard

During cold periods (e.g., winter) PCC slabs contract If these openings become filled with

incompressible material (such as rocks or soil), subsequent PCC slab expansion during hot periods (e.g., spring, summer) may cause high

If these stresses are great enough, the slabs eve the stresses. Blowup can be

(reduces slab contact area and provides ll the joint/crack)

(weakens the slab near the joint/crack area)thaw damage (weakens the slab near the joint/crack



extreme cases (as in the

During cold periods (e.g., winter) PCC slabs contract s become filled with

incompressible material (such as rocks or soil), subsequent PCC slab expansion during hot periods (e.g., spring, summer) may cause high

If these stresses are great enough, the slabs Blowup can be

(reduces slab contact area and provides ll the joint/crack)

(weakens the slab near the joint/crack area)thaw damage (weakens the slab near the joint/crack



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extreme cases (as in the

During cold periods (e.g., winter) PCC slabs contract

thaw damage (weakens the slab near the joint/crack

7.2

Descriptioncorner.ft) or so.caused by high corner stresses.

Problem:fault, spall and disintegrate

Possible Causes:combined with a loss of support, poor load transfer across the joint, curling stresses and warping stresse

Repair


7.2 CORNER BREAK

Description: A crack that intersects the PCC slab joints near the corner. "Near the corner" ift) or so. A corner break extends through the entire slab and is caused by high corner stresses.

Problem: Roughnefault, spall and disintegrate

Possible Causes:combined with a loss of support, poor load transfer across the joint, curling stresses and warping stresse

Repair: Full-depth patch

Figure5:CORNER BREAK AT STREETS


CORNER BREAK

: A crack that intersects the PCC slab joints near the "Near the corner" is typically defined as within about 2 m

A corner break extends through the entire slab and is caused by high corner stresses.

Roughness, moisture infiltration, severe corner breaks will fault, spall and disintegrate

Severe corner stresses caused by load repetitions combined with a loss of support, poor load transfer across the joint, curling stresses and warping stresse

depth patch.

Figure5:CORNER BREAK AT STREETS


: A crack that intersects the PCC slab joints near the s typically defined as within about 2 m

A corner break extends through the entire slab and is

moisture infiltration, severe corner breaks will

Severe corner stresses caused by load repetitions combined with a loss of support, poor load transfer across the joint, curling stresses and warping stresses.

Figure 6:CORNER BREAK AT HIGHWAY

INFRASTRUCTURE


: A crack that intersects the PCC slab joints near the s typically defined as within about 2 m

A corner break extends through the entire slab and is


Severe corner stresses caused by load repetitions combined with a loss of support, poor load transfer across the joint,


INFRASTRUCTURE


s typically defined as within about 2 m (6


Severe corner stresses caused by load repetitions combined with a loss of support, poor load transfer across the joint,

7 .3

Description:joint corner or crack.large aggregate within the PCC slab.PCC dist

Problem:disintegration

Possible Causes:

Repairproblem. Although a the affected area, it does not address the root problem and will not, or course, prevent "D" cracking elsewhere




DURABILITY CRACKING

Figure

Description: Series of closely spaced, crescentjoint corner or crack.large aggregate within the PCC slab.PCC distress and is not unique to pavement PCC.

Problem: Some roughnessdisintegration

Possible Causes: Freeze

Repair: "D" cracking is indicative of a general aggregate freezeproblem. Although a the affected area, it does not address the root problem and will not, or course, prevent "D" cracking elsewhere



DURABILITY CRACKING ("D" CRACKING)

Figure 7: D CRACKING AT PANEL CORNERS

Series of closely spaced, crescentjoint corner or crack. It is caused by freezelarge aggregate within the PCC slab.

ress and is not unique to pavement PCC.

roughness, leads to spalling and eventual slab

Freeze-thaw susceptible aggregate

: "D" cracking is indicative of a general aggregate freezeproblem. Although a full-depth patchthe affected area, it does not address the root problem and will not, or course, prevent "D" cracking elsewhere



("D" CRACKING)

: D CRACKING AT PANEL CORNERS

Series of closely spaced, crescent-shaped cracks near a It is caused by freeze-thaw expansion of the

Durability cracking is a general ress and is not unique to pavement PCC.

, leads to spalling and eventual slab

thaw susceptible aggregate.

: "D" cracking is indicative of a general aggregate freezedepth patch or partial-depth patch

the affected area, it does not address the root problem and will not, or course, prevent "D" cracking elsewhere.



shaped cracks near a thaw expansion of the

Durability cracking is a general

, leads to spalling and eventual slab

: "D" cracking is indicative of a general aggregate freeze-thaw depth patch can repair

the affected area, it does not address the root problem and will not, or



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can repair the affected area, it does not address the root problem and will not, or

7.4

difference in elevation across a joint or crack usually associated with undowelslab due to pumping, the most common faulting mechanism.is noticeable when the areaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 mm (0.15 in), diamond grinding or other rehabilitation measures should

Problem:

Possible Causes:pumpingwarping.


7.4 FAULTING

difference in elevation across a joint or crack usually associated with undoweled JPCP.slab due to pumping, the most common faulting mechanism.is noticeable when the areaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 mm (0.15 in), diamond grinding or other rehabilitation measures should be considered

Problem: Roughness

Possible Causes:pumping. Faulting can also be cauwarping.


FAULTING

difference in elevation across a joint or crack usually associated with Usually the approach slab is higher than the leave

slab due to pumping, the most common faulting mechanism.is noticeable when the average faulting in the pavement section reaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 mm (0.15 in), diamond grinding or other rehabilitation measures

be considered.

Roughness

Most commonly, Faulting can also be cau

Figure 8:SEVERE FAULTING


difference in elevation across a joint or crack usually associated with Usually the approach slab is higher than the leave

slab due to pumping, the most common faulting mechanism.verage faulting in the pavement section

reaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 mm (0.15 in), diamond grinding or other rehabilitation measures

Most commonly, faulting is a result of slab Faulting can also be caused by slab settlement, curling and

Figure 8:SEVERE FAULTING

INFRASTRUCTURE


Description: A difference in elevation across a joint or crack usually associated with

Usually the approach slab is higher than the leave slab due to pumping, the most common faulting mechanism. Faulting

verage faulting in the pavement section reaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 mm (0.15 in), diamond grinding or other rehabilitation measures

faulting is a result of slab sed by slab settlement, curling and

INFRASTRUCTURE


A difference in elevation across a joint or crack usually associated with

Usually the approach slab is higher than the leave Faulting

reaches about 2.5 mm (0.1 inch). When the average faulting reaches 4

sed by slab settlement, curling and

Repairrepaired.and 12.5 mm (0.5 inch) is a candidate for a dowel bar retrofit.total reconstruction.

7.5

Figure 9:EXPOSED FAILURE WITH RUSTED DOWEL BARS

Description:joint dowels.

Problem:



Repair: Faulting heights of less than 3 mm (0.125 inch) need not be repaired. Faulting in an and 12.5 mm (0.5 inch) is a candidate for a dowel bar retrofit. Faulting in excess of 12.5 mm (0.5 inches) generally warrants total reconstruction.

JOINT LOAD TRANSFER


Description: Transverse crack or corner break developed as a result of joint dowels.

Problem: Indicator of a failed load transfer system,



: Faulting heights of less than 3 mm (0.125 inch) need not be Faulting in an undoweled

and 12.5 mm (0.5 inch) is a candidate for a dowel bar Faulting in excess of 12.5 mm (0.5 inches) generally warrants

total reconstruction.

JOINT LOAD TRANSFER SYSTEM DETERIORATION


Transverse crack or corner break developed as a result of

Indicator of a failed load transfer system,



: Faulting heights of less than 3 mm (0.125 inch) need not be undoweled JPCP between 3 mm (0.125 inch)


SYSTEM DETERIORATION

Figure 9:EXPOSED FAILURE WITH RUSTED DOWEL BARS Figure 10:PATCHED FAILURE


Indicator of a failed load transfer system, roughness



: Faulting heights of less than 3 mm (0.125 inch) need not be between 3 mm (0.125 inch)


SYSTEM DETERIORATION

Figure 10:PATCHED FAILURE


roughness



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between 3 mm (0.125 inch)

Faulting in excess of 12.5 mm (0.5 inches) generally warrants


Possible Causes:reasons:

Repairsystem followed by a


Possible Causes:reasons:

Corrosionover timecreates tensile stresses around the dowel bars, and a severely corroded dowel bar is weaker and may fail after repeated loading.

Misalignmentthe slab edge may crebreak the slab.construction or during dowel bar retrofits.

Repair: Removal and replacement of the affected joint load transfer system followed by a


Load transfer dowel bars can fail for two principal

Corrosion. If inadequately protected, dowel bars can corrode over time. The corrosion products occupy volume, which creates tensile stresses around the dowel bars, and a severely corroded dowel bar is weaker and may fail after repeated

Misalignment. Dowel bars inserted crooked or too close to the slab edge may create localized stresses high enough to break the slab. Misalignment can occur during original construction or during dowel bar retrofits.

: Removal and replacement of the affected joint load transfer system followed by a full-depth patch



If inadequately protected, dowel bars can corrode The corrosion products occupy volume, which

creates tensile stresses around the dowel bars, and a severely corroded dowel bar is weaker and may fail after repeated

Dowel bars inserted crooked or too close to ate localized stresses high enough to

Misalignment can occur during original construction or during dowel bar retrofits.

: Removal and replacement of the affected joint load transfer depth patch for affected area.

INFRASTRUCTURE




creates tensile stresses around the dowel bars, and a severely corroded dowel bar is weaker and may fail after repeated


Misalignment can occur during original construction or during dowel bar retrofits.

: Removal and replacement of the affected joint load transfer affected area.

INFRASTRUCTURE




creates tensile stresses around the dowel bars, and a severely


: Removal and replacement of the affected joint load transfer

7.6

Description:blowups that extend across the entire slab.divide an individual slab into two to four pieces.

Problem:base/subbase support, cracks will eventually spall and disintegrate if not sealed

Possible Causesgradient curling, moisture stresses and loss of support.

Repaircrack sealing.full-



LINEAR (PANEL) CRACK

Description: Linear cracks not associated with corner breaks or blowups that extend across the entire slab.divide an individual slab into two to four pieces.

Problem: Roughnessbase/subbase support, cracks will eventually spall and disintegrate if not sealed

Possible Causes: Usually a combination of traffic loading, thermal gradient curling, moisture stresses and loss of support.

Repair: Slabs with a single, narrow linear crack may be repaired by crack sealing. More than one linear crack generally warrants a

-depth patch.



LINEAR (PANEL) CRACKING

Figure11: PANEL CRACK

Linear cracks not associated with corner breaks or blowups that extend across the entire slab.divide an individual slab into two to four pieces.

Roughness, allows moisture infiltration leading to erosion of base/subbase support, cracks will eventually spall and disintegrate if

Usually a combination of traffic loading, thermal gradient curling, moisture stresses and loss of support.

: Slabs with a single, narrow linear crack may be repaired by More than one linear crack generally warrants a



ING

Figure11: PANEL CRACK

Linear cracks not associated with corner breaks or blowups that extend across the entire slab. Typically, these cracks divide an individual slab into two to four pieces.

, allows moisture infiltration leading to erosion of base/subbase support, cracks will eventually spall and disintegrate if





Linear cracks not associated with corner breaks or Typically, these cracks






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7.7

Description:material to repair the existdefect no matter how well it performs.

Problem:

Possible Causes:been removed and patched

Repaircan be removed is through an


7.7 PATCHING

Description: An area of pavement that has been replaced with new material to repair the existdefect no matter how well it performs.

Problem: Roughness

Possible Causes:been removed and patched

Repair: Patches are themselves a repair action.can be removed is through an


PATCHING

Figure 12:PATCH ON A STREET

An area of pavement that has been replaced with new material to repair the existing pavement.defect no matter how well it performs.

Roughness

Previous localized pavement deterioration tbeen removed and patched &Utility cuts

are themselves a repair action.can be removed is through an overlay


Figure 12:PATCH ON A STREET

An area of pavement that has been replaced with new ing pavement. A patch is considered a

defect no matter how well it performs.

Previous localized pavement deterioration t&Utility cuts

are themselves a repair action. The only way they overlay or slab replacement.

INFRASTRUCTURE


An area of pavement that has been replaced with new A patch is considered a

Previous localized pavement deterioration that has

The only way they or slab replacement.

INFRASTRUCTURE


An area of pavement that has been replaced with new A patch is considered a

hat has

The only way they

7.8

Description:on the surface contains few rough or angular aggregate particles.

Problem:

Possible Causes:pavement ages the protruding rough, angular particles become polished.abrasion

Repair



POLISHED AGGREGAT

Figure13:POLISHED AGGREGATE AFTER 40 YEARS

Description: Areas of PCC pavement where the portion of aggregate on the surface contains few rough or angular aggregate particles.

Problem: Decreased

Possible Causes: Repeated traffic applications.pavement ages the protruding rough, angular particles become polished. This can occur quicker if the aggregate is abrasion or subject to excessive

Repair: Diamond grinding



POLISHED AGGREGATE


Areas of PCC pavement where the portion of aggregate on the surface contains few rough or angular aggregate particles.

Decreased skid resistance

Repeated traffic applications.pavement ages the protruding rough, angular particles become

This can occur quicker if the aggregate is or subject to excessive studded tire wear

Diamond grinding or overlay.





Repeated traffic applications. Generalpavement ages the protruding rough, angular particles become

This can occur quicker if the aggregate is susceptistudded tire wear.

.





Generally, as a pavement ages the protruding rough, angular particles become

susceptible to



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7.9

Description:leavi(1

Problem:

Possible Causes:durability.as:


7.9 POPOUTS

Description: Small pieces of PCC that break loose from the surface leaving small divots or pock marks.(1 - 4 inches) in diameter and from 25

Problem: Roughness

Possible Causes:durability. Poor durability can be a result of a number of items such as:

Poor aggregate freeze Expansive aggregates Alkali-aggregate reactions

Figure 14:LARGE POPOUTS


Small pieces of PCC that break loose from the surface divots or pock marks.

4 inches) in diameter and from 25

Roughness, usually an indic

Popouts usually occur as a result of poor aggregate Poor durability can be a result of a number of items such

Poor aggregate freeze-thaw resistanceExpansive aggregates

aggregate reactions

Figure 14:LARGE POPOUTS


Small pieces of PCC that break loose from the surface divots or pock marks. Popouts range from 25

4 inches) in diameter and from 25 - 50 mm (1 -

usually an indicator of poor material


thaw resistance

aggregate reactions

Figure 15:POPOUT CLOSE UP

INFRASTRUCTURE


Small pieces of PCC that break loose from the surface Popouts range from 25 - 100 mm

- 2 inches) deep.

ator of poor material



INFRASTRUCTURE


Small pieces of PCC that break loose from the surface 100 mm

2 inches) deep.


Repapopouts or a group of popouts can generally be repaired with a

parti

Description:pieces.

Problem:base/subbase support, cracks will spall and disintegrate.

Possible Causes:inadequate consolidation.corrosion, inadequate amount of steel, exc




Repair: Isolated low severity popouts may not warrant repair.popouts or a group of popouts can generally be repaired with a

partial-depth patch

7.10 PUNCHOUT

Description: Localized slab portion broken into several pieces. Typically a concern only with

Problem: Roughnessbase/subbase support, cracks will spall and disintegrate.

Possible Causes: Can indicate a localized construction defect such as inadequate consolidation.corrosion, inadequate amount of steel, exc



: Isolated low severity popouts may not warrant repair.popouts or a group of popouts can generally be repaired with a

depth patch.

PUNCHOUT

Figure 16:SEVERE PUNCHOUT

Localized slab portion broken into several Typically a concern only with

Roughness, allows moisture infiltration base/subbase support, cracks will spall and disintegrate.

Can indicate a localized construction defect such as inadequate consolidation. In CRCP, it can be caused by steel corrosion, inadequate amount of steel, exc



: Isolated low severity popouts may not warrant repair.popouts or a group of popouts can generally be repaired with a

Figure 16:SEVERE PUNCHOUT

Localized slab portion broken into several Typically a concern only with CRCP.

allows moisture infiltration leading to erosion of base/subbase support, cracks will spall and disintegrate.

Can indicate a localized construction defect such as In CRCP, it can be caused by steel

corrosion, inadequate amount of steel, excessively wide shrinkage



: Isolated low severity popouts may not warrant repair. Larger popouts or a group of popouts can generally be repaired with a

Localized slab portion broken into several

leading to erosion of base/subbase support, cracks will spall and disintegrate.

Can indicate a localized construction defect such as In CRCP, it can be caused by steel

essively wide shrinkage



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Larger

leading to erosion of

Can indicate a localized construction defect such as

cracks or excessively close shrinkage cracks.Repair

7.11

Description:caused by reactive aggregates.either expand or develop expansive by products when introduced to certain chemical com

Problem:lead to PCC slab disintegration.


cracks or excessively close shrinkage cracks.Repair: Full-depth patch

7.11 REACTIVE AGGREGATE D

Description: Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates.either expand or develop expansive by products when introduced to certain chemical com

Problem: Roughnesslead to PCC slab disintegration.


cracks or excessively close shrinkage cracks.depth patch.

REACTIVE AGGREGATE D

Figure 17:SEVERE CRAZING

Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates. Reactive aggregates are those that either expand or develop expansive by products when introduced to certain chemical compounds.

Roughness, an indication of poor aggregate lead to PCC slab disintegration.


cracks or excessively close shrinkage cracks.

REACTIVE AGGREGATE DISTRESSES

Figure 17:SEVERE CRAZING

Pattern or map cracking (crazing) on the PCC slab surface Reactive aggregates are those that

either expand or develop expansive by products when introduced to

, an indication of poor aggregate

INFRASTRUCTURE




, an indication of poor aggregate - will eventually

INFRASTRUCTURE




will eventually

Possible Causes:qualities.reaction

Repairreplacement for large areas of scaling.

7.12

Description:are not located at joints.entire depth of the slab.they occur in an uncontrolled manner (e.g., at locations outside of contraction joints

Figure 18:SHRINKAGE



Possible Causes: This type of distress is inqualities. Most commonly, it is a result of an reaction.

Repair: Partial-depthreplacement for large areas of scaling.

7.12 SHRINKAGE CRACKING

Description: Hairline cracks formed during PCC setting and curing that are not located at joints.entire depth of the slab.they occur in an uncontrolled manner (e.g., at locations outside of contraction joints in

Figure 18:SHRINKAGE CRACKS ON NEWLY CASTED SLABS



This type of distress is inMost commonly, it is a result of an

depth patch for small areas of scaling or slab replacement for large areas of scaling.

SHRINKAGE CRACKING

Hairline cracks formed during PCC setting and curing that are not located at joints. Usually, they do not extend through the entire depth of the slab. Shrinkage cracks are they occur in an uncontrolled manner (e.g., at locations outside of

in JPCP or too close together in

CRACKS ON NEWLY CASTED SLABS



This type of distress is indicative of poor aggregate Most commonly, it is a result of an alkali-aggregate

patch for small areas of scaling or slab replacement for large areas of scaling.

Hairline cracks formed during PCC setting and curing that Usually, they do not extend through the Shrinkage cracks are considered a distress if

they occur in an uncontrolled manner (e.g., at locations outside of or too close together in CRCP

Figure 19:SEVERE SHRINKAGE CRACKS



dicative of poor aggregate aggregate

patch for small areas of scaling or slab

Hairline cracks formed during PCC setting and curing that Usually, they do not extend through the

considered a distress if they occur in an uncontrolled manner (e.g., at locations outside of

CRCP).




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Hairline cracks formed during PCC setting and curing that

considered a distress if


Problem:JPCP they will eventually widen and allow moisture infiltration.CRCP, if they are allowed to get much wider than about 0.5 mm (0.02 inches) they can allow moisture infiltration (CRSI, 1996).

Possible Causes:shrinkage cracks are expected in rigid pavement and provisions for their control are made.can indicate:


Problem: Aesthetics, indication JPCP they will eventually widen and allow moisture infiltration.CRCP, if they are allowed to get much wider than about 0.5 mm (0.02 inches) they can allow moisture infiltration (CRSI, 1996).

Possible Causes:shrinkage cracks are expected in rigid pavement and provisions for their control are made.can indicate:

Contraction joints sawed too latejoints are sawed too late the PCC may already have cracked in an undesirable location.

Poor reinforcing steel designsteel design should result in shrinkage cracks every 1.2 - 10 ft.).

Improper curing techniquedry too quickly, it will shrink too quickly and crack.

High early strength PCCconstructed or rehabilitated section to traffic, high early-strength PCC may be used.high heat of hydrationgreater extent than typical PCC made from unmodified Portland cement


Aesthetics, indication of uncontrolled slab shrinkage.JPCP they will eventually widen and allow moisture infiltration.CRCP, if they are allowed to get much wider than about 0.5 mm (0.02 inches) they can allow moisture infiltration (CRSI, 1996).

All PCC will shrink as it sets and cures, therefore shrinkage cracks are expected in rigid pavement and provisions for their control are made. However, uncontrolled shrinkage cracking

Contraction joints sawed too latejoints are sawed too late the PCC may already have cracked in an undesirable location.Poor reinforcing steel designsteel design should result in shrinkage cracks every 1.2

Improper curing techniquedry too quickly, it will shrink too quickly and crack.High early strength PCC.constructed or rehabilitated section to traffic, high

strength PCC may be used.heat of hydration and shrinks more quickly and to a

greater extent than typical PCC made from unmodified Portland cement.


of uncontrolled slab shrinkage.JPCP they will eventually widen and allow moisture infiltration.CRCP, if they are allowed to get much wider than about 0.5 mm (0.02 inches) they can allow moisture infiltration (CRSI, 1996).

will shrink as it sets and cures, therefore shrinkage cracks are expected in rigid pavement and provisions for

However, uncontrolled shrinkage cracking

Contraction joints sawed too late. In JPCP, if contraction joints are sawed too late the PCC may already have cracked in

Poor reinforcing steel design. In CRCP, proper reinforcing steel design should result in shrinkage cracks every 1.2

Improper curing technique. If the slab surface is allowed to dry too quickly, it will shrink too quickly and crack.

In an effort to quickly open a newly constructed or rehabilitated section to traffic, high

strength PCC may be used. This type of PCC can and shrinks more quickly and to a

greater extent than typical PCC made from unmodified

INFRASTRUCTURE


of uncontrolled slab shrinkage. In JPCP they will eventually widen and allow moisture infiltration. In CRCP, if they are allowed to get much wider than about 0.5 mm (0.02 inches) they can allow moisture infiltration (CRSI, 1996).

will shrink as it sets and cures, therefore shrinkage cracks are expected in rigid pavement and provisions for

However, uncontrolled shrinkage cracking

In JPCP, if contraction joints are sawed too late the PCC may already have cracked in

In CRCP, proper reinforcing steel design should result in shrinkage cracks every 1.2 - 3 m (4

he slab surface is allowed to dry too quickly, it will shrink too quickly and crack.

In an effort to quickly open a newly constructed or rehabilitated section to traffic, high

This type of PCC can have a and shrinks more quickly and to a

greater extent than typical PCC made from unmodified Type 1

INFRASTRUCTURE


In In

CRCP, if they are allowed to get much wider than about 0.5 mm (0.02

shrinkage cracks are expected in rigid pavement and provisions for However, uncontrolled shrinkage cracking

joints are sawed too late the PCC may already have cracked in

In CRCP, proper reinforcing 3 m (4

he slab surface is allowed to

In an effort to quickly open a newly

have a

Type 1

Repaircan be sealed and the slab should perform adequately.situations, the entire s

7.13

Description:edges.

Figure 20:LINEAR CRACK SPALLING



Repair: In mild to moderate severity situations, the shrinkage cracks can be sealed and the slab should perform adequately.situations, the entire s

7.13 SPALLING

Description: Cracking, breaking or chipping of joint/crack edges. Usually occurs within about 0.6 m (2 ft.) of joint/crack edge.




: In mild to moderate severity situations, the shrinkage cracks can be sealed and the slab should perform adequately.situations, the entire slab may need replacement

Cracking, breaking or chipping of joint/crack Usually occurs within about 0.6 m (2 ft.) of joint/crack edge.




: In mild to moderate severity situations, the shrinkage cracks can be sealed and the slab should perform adequately.

lab may need replacement.


Figure 21:SPALLING FROM A BAD

CONSTRUCTION JOINT



: In mild to moderate severity situations, the shrinkage cracks can be sealed and the slab should perform adequately. In severe


Figure 21:SPALLING FROM A BAD

CONSTRUCTION JOINT



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Problem: Loose debris on the pavement, roughness, generally an indicator of advanced joint/crack deterioration

Possible Causes: Possible causes are:

Excessive stresses at the joint/crack caused by infiltration of incompressible materials and subsequent expansion (can also cause blowups).

Disintegration of the PCC from freeze-thaw action or "D" cracking.

Weak PCC at a joint caused by inadequate consolidation during construction. This can sometimes occur at a construction joint if (1) low quality PCC is used to fill in the last bit of slab volume or (2) dowels are improperly inserted.

Misalignment or corroded dowel. Heavy traffic loading.

Repair: Spalling less than 75 mm (3 inches) from the crack face can generally be repaired with a partial-depth patch. Spalling greater than about 75 mm (3 inches) from the crack face may indicated possible spalling at the joint bottom and should be repaired with a full-depth patch.

8 CONCLUSION

The various failures responsible for the degradation of the rigid pavements have been studied and the possible remedies and

preventive measures are also thoroughly noted down. Thus proper and regular maintenance and good construction practices would help

to prevent the pavement failures.

9 REFERENCES

HIGHWAY ENGINEERING-8TH EDITION BY S.K KHANNA & C.E.G JUSTO

NATIONAL SEMINAR ON CONCRETE PAVEMENTS & PROBLEMS- 2003 BY SCHOOL OF BUILDING SCIENCE & TECHNOLOGY,CEPT UNIVERSITY,AHMEDABAD

TRAINING REPORT ON RIGID PAVEMENT DISTRESSES-2005 BY WASHINGTON UNIVERSITY

Infrastructure-Failures of Rigid Pavements

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