Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports (2019) / Chapter Skim
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Pages 9-33
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From page 9... ...
9 As described in Chapter 1, ASR, at various levels and severities, has been confirmed in the 48 contiguous states (Thomas et al.
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10 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports harmful ASR on 42 concrete bridges, 2 pavements, 1 tunnel, and 56 minor structures that were built between 1940 and 1954 after the adoption of the limit (Tremper and Kovanda 1955)
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Literature Review Summary 11 Mechanisms of ASR Development As defined previously, ASR is a deleterious reaction that occurs in concrete between reactive silica present in the aggregate and the alkalis present in the pore solution of the hydrated cementitious paste. The reaction entails the dissolution of the silica, the formation of an alkali-silica gel, and interaction with calcium.
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12 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports As explained by Thomas and colleagues (2013a)
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Literature Review Summary 13 potassium acetate deicer solutions when used at adequate dosage levels (Rangaraju 2007)
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14 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports a)
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Literature Review Summary 15 The PCI procedure does recognize that ASR is material dependent and states that coring and concrete petrographic analysis is the only definitive means of confirming ASR. Nevertheless, the procedure makes a diagnosis based on visible conditions only, and with the absence of a "map cracking" distress call in the procedure, the result is that PCI surveys performed on airport pavements may report an ASR condition that may or may not be legitimate.
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16 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports • Field Identification Tests.
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Literature Review Summary 17 Preventing ASR in New Concrete Construction General Approach Tremendous advancements have been made in the past decade or so with regard to the prevention of ASR in new concrete construction. Basically four strategies are available to mitigate ASR in new concrete mixtures (Thomas et al.
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18 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports the need for alternative sources and new methods of using existing fly ash was identified (AASHTO 2016)
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Literature Review Summary 19 less than 13%, a maximum loss on ignition (a measure of unburned carbon) of 6%, and a total alkali content of less than 3% (FAA 2014)
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20 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports measures and are based largely on the significant work performed by FHWA (Thomas et al.
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Literature Review Summary 21 Test Method Comments ASTM C227, Standard Test Method for Potential Alkali Reactivity of CementAggregate Combinations (Mortar Bar Method) • Mortar bar (2.25 parts aggregate to 1 part cement)
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22 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports test that can be conducted during the mixture design process or even during construction if one of the relevant concrete constituents changes.
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Literature Review Summary 23 temporary relief. More recently, topical surface treatments to reduce moisture ingress or to slow the ASR reaction have been used by a few agencies, but their long-term effectiveness is not known.
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24 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports the addition of the edge drains does nothing to address the deterioration that has already occurred in the pavement, which would require some corrective repairs or treatments.
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Literature Review Summary 25 A study on the use of silanes on an ASR-afflicted concrete pavement was performed in 2012 on a 12-mile (19-km) stretch of I-530 near Pine Bluff, AR (Thomas et al.
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26 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports The depth of penetration of the lithium is an ongoing concern, as it must penetrate deep enough into the concrete to affect the ongoing reactivity within the mass of the slab.
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Literature Review Summary 27 Airport, Phoenix Sky Harbor Airport, and Hartsfield-Jackson Atlanta International Airport, and featured the use of lithium applied at a rate of 220 ft2/gal (5.4 m2/L) (applied in two separate 440 ft2/gal [10.8 m2/L]
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28 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports HMWM was also used on a pavement facility at Seymour-Johnson Airforce Base (AFB)
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Literature Review Summary 29 substrate is critical, and the presence and movement of joints must be accommodated. Expedient methods featuring cold milling and rapid-setting materials are available to limit closure times for partial-depth repair work (Hammons and Saeed 2010)
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30 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports typically 1 to 2 inches (25 to 50 mm)
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Literature Review Summary 31 strongly dependent on the underlying pavement conditions, and subsequently may require a significant amount of pre-overlay repair. In severe cases of ASR, rubblization of the existing concrete pavement may need to be considered to disrupt the existing slab to eliminate damage due to future expansion, but this often drives up the required thickness of the overlay.
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32 Practices to Mitigate Alkali-Silica Reaction (ASR) Affected Pavements at Airports aggregate as a base course under Item P-219, but notes that "concrete that has deteriorated from alkali-silica reaction (ASR)
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Literature Review Summary 33 Mitigation methods for new concrete mixtures are described and noted to include four general approaches: 1. Avoid the use of susceptible aggregates.
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