 FIG.13 - Cracking associated with ASR at mid-span in bridge deck. Predominant cracks are oriented longitudinally with respect to deck (top to bottom in photo), and are interconnected by short, tight microcracks that extend transversely or randomly between longitudinal cracks. Cracking may be more severe over girders. No consistent relationship exists between location of cracks and steel in top reinforcing mat. |
 FIG.14 - Characteristic cracking associated with ASR in corner of bridge deck. Cracks tend to "curve" around corner from transverse orientation at end of deck to longitudinal orientation toward middle of span (See Fig.13). End of deck is along tarred strip at bottom of photo. Cracking pattern is due to restraint developed by the reinforcing steel and other concrete members in and around the deck. Areas, such as around drains, where rainwater and/or solubilized deicer flows or collects on a deck tend to show more severe cracking. |
 FIG.15 - Four (4) inch diameter core taken from area of bridge deck shown in Fig.14. Major cracking occurs full-depth in the core and is enhanced by wetting and partial drying. Dark bands follow cracks that still contain water. Initiation of cracking is attributed to ASR. Restraint by reinforcing steel to volume change may have influenced crack pattern. |
 FIG.16 - Longitudinal crack, along top of parapet wall, associated with ASR. Other, much finer cracks form network of cracking on top surface. Such cracking could be attributed to drying shrinkage or corrosion of embedded steel. Corroborating evidence, such as petrographic analysis, is necessary to verify association of ASR with cracking. |
 FIG.17 - Cracking associated with ASR in end block of concrete guard rail on bridge deck. This type of cracking could result from freezing and thawing. In essentially frost-free climates, ASR is the likely cause of cracking. Individual cracks are stained and filled with calcium carbonate and ASR gel. Evidence of overall abnormal expansion due to ASR may not be apparent in such concrete units. Do not interpret this type of cracking as confirming evidence of ASR in areas of freezing and thawing. In these cases, however, initial cracking due to ASR may lead to faster progression of freeze-thaw damage by creating a pathway for moisture to enter into the concrete mass expanding the cracks upon freezing. |
 FIG.18 - Cracking and differential movement of abutting sections of parapet wall in bridge structure affected by ASR. Joint is tightly closed and lateral offset has occurred. Cracking and spalling have developed on left side of joint, and cracking and incipient spalling have developed around embedded metal plate on right side. Deposits that most likely include ASR reaction products are clearly visible in and around cracks. In such cases confirmation should be made that distress has not resulted from other factors, such as foundation movements, freezing and thawing or vehicle impact. In cases where cracking has advanced to this stage the visible damage, although initiated by ASR, is probably due to a combination of factors and the structure will continue to deteriorate. In addition, damage immediately attributable to ASR can continue at an expedited rate because the advanced cracking provides easy channels for greater ingress of moisture and external sources of alkali such as from deicer salts. This effect is particularly noticeable in cases where extent of reaction is limited by the amount of moisture or available alkali. |
 FIG.19 - Major vertical crack with less prominent horizontal and random cracks in end of parapet wall. White deposit at base is mixture of ASR gel and calcium carbonate. This evidence is typical of advanced stages of ASR. However, such deposits most commonly consist of calcium carbonate, which by itself is not indicative of ASR. Presence of occurrence of ASR expansion and of ASR gel must be confirmed in other ways. |
 FIG.20 - Closed joint between sections of parapet wall may have resulted from expansion due to ASR, as shown. Inspection should be made to determine if a foundation shift may have caused a tight joint. Such evidence should be used only as supporting evidence of ASR unless indicated otherwise. Evidence of closed joints such as the one in the picture throughout the structure are usually indications that the cause is ASR rather than foundation shifts. |
| FIG.21 - Horizontal cracking extending the length of the pier cap of bridge over fresh water. Such cracking is often associated with ASR but might also be due to corrosion of embedded reinforcing steel, or a combination of the two. This area is moist and collects condensation thus insuring sufficient moisture for ASR. Initial ASR cracking allows the ingress of moisture and carbon dioxide into the concrete close to the steel, resulting in a drop in pH around the steel providing the right conditions for initiation of corrosion. Corroborative evidence is necessary to confirm ASR as a likely cause of this type of cracking. |
 FIG.22 - Cracking in top cord of concrete arch bridge. White deposits of ASR gel and calcium carbonate exude from cracks. Such cracking may also develop from freezing and thawing, and the white deposits may or may not contain ASR gel. In frost-free climates, ASR is the most probable cause of the cracking but corroborating evidence should be obtained to confirm its development. |
 FIG.23 - Bridge column showing cracking associated with ASR. Predominant cracks are oriented longitudinally, but are connected in irregular pattern by short transverse cracks and by fine random microcracks. White deposits on column contain ASR gel. Cracking patterns are related to the configuration of the embedded reinforcing steel. |
 FIG.24 - Bridge columns showing longitudinal crack at base near sloped concrete surface of bridge embarkment. This cracking could be due to ASR or, for example, to corrosion of embedded reinforcing steel. Further investigation, including microscopic examination of concrete, is necessary to confirm causes. In this case, ASR has developed in the concrete. In these situations cracking at the base is more apparent and prevalent than in the rest of the column due to wicking of moisture from underlying soil and splashing by passing vehicles. If chloride deicers are used in the area, ASR cracking will promote ingress of chloride into the concrete and trigger corrosion of reinforcing steel. |
 FIG.25 - Cracking associated with ASR in bridge column. Predominant cracks are oriented longitudinally in column, and are interconnected by short transverse and random cracks. Longitudinal cracks occasionally develop at regular spacings, possibly controlled by location of embedded vertical reinforcing steel. Drying shrinkage has probably enlarged cracks. |
 FIG.26 - Closeup of cracking associated with ASR in bridge column. The most prominent crack is oriented approximately longitudinally in the column and usually does not extend along the full length of column. Finer microcracks interconnect in random fashion. Drying shrinkage may have contributed to cracking shown in photo. |
 FIG.27 - Cracking associated with ASR in wingwall of bridge structure. Major cracks tend to show subhorizontal orientation and are more strongly developed at lower levels, where humidity and moisture are at the highest due to wicking effects from soil and shielding from solar drying. Cracking of this type also may result from frost action and must be corroborated with other evidence to positively assign ASR as a cause. In climates that are essentially frost-free, ASR is a probable cause. |
 FIG.28 - Curb section bordering approach slab to bridge structure. Curb shows distress due to ASR. Displaced wedge-shaped curb section shows uplift from original position. Longitudinal and fine random cracks are typical distress due to ASR, but uplift may have resulted from other causes, such as shifting of entire approach slab. Use such observations only as possible evidence of ASR. |
