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Title	Mitigation of Alkali-Silica Reactivity in New Concrete in New Hampshire-Phase 2 Minimum Amounts of Admixture(s) Needed to Significantly Minimize ASR
Accession No	01029097
Authors	Lane, Richard M; Fish, Marc F
Corp. Authors / Publisher	New Hampshire Department of Transportation ; Federal Highway Administration
Publication Date	20050908
Edition	Final Report
Description	17p; Appendices(2); Photos(8); References(18); Tables(6)
Media Type	Print
Languages	English
Abstract	A Phase 2 research study was undertaken to identify the types and amounts of admixture(s) needed to reduce Alkali-Silica Reactivity (ASR) expansion in new concrete made with reactive New Hampshire aggregates. The Phase 1 study found that 25% of the New Hampshire concrete aggregates tested under ASTM C1260-94 are potentially reactive (0.1% or greater elongation at 14 days) and identified ASR in over 40% of the concrete cores taken from existing bridge structures throughout the state. The objectives of the Phase 2 research were the following: (1) Evaluate different admixtures for their effectiveness in mitigating the development of ASR in new concrete in New Hampshire through ASTM C1260-94 accelerated mortar bar testing; (2) Verify the minimum amounts of admixture(s) needed to reduce ASR expansion (to less than 0.1% at 14 days) in new concrete made with reactive NH aggregates; (3) Evaluate both mineral and chemical admixture(s) to include Fly Ash, Ground Granulated Blast Furnace Slag (GGBF) and Silica Fume; (4) Evaluate the ability of blended cement, ternary cement and high-reactivity metakaolin (HRM) to control expansion due to ASR; and (5) Conduct petrographic thin section analysis on mortar bars of selected Portland Cement Concrete (PCC) mixes to confirm the mitigation of ASR at the microscopic level. The Phase 2 research utilized the ASTM C1260-94 accelerated mortar bar test to identify the amounts of admixture(s) needed to reduce expansion in new concrete in New Hampshire to less than 0.1% elongation at 14 days. Several of the more highly reactive concrete aggregates in New Hampshire were utilized in the PCC mixes for the mortar bars. The research demonstrated that both chemical and mineral admixture(s), some combinations of admixtures, blended cement, ternary cement and HRM all have the ability to control (less than 0.1% elongation at 14 days) ASR in new concrete made with New Hampshire reactive aggregates. The development of ASR was not effectively mitigated with the admixture of silica fume when utilizing the ASTM C1260-94 test method. Petrographic thin section analysis on mortar bars from selected PCC mixes confirmed the ability of these products to mitigate the development of ASR.
TRT Terms	Admixtures ; Alkali silica reactions ; Cement ; Concrete ; Concrete aggregates ; Evaluation ; Expansion ; Fly ash ; Mortar ; Portland cement concrete ; Silica fume
Geographical Terms	New Hampshire
Identifier Terms	ASTM C 1260
Other Terms	Accelerated mortar bar test; Alkali silica reactivity; Ground granulated blast furnace slag; High-reactivity metakaolin; Mitigation (Chemical reactivity); Petrographic analysis; Ternary cements
Subject Areas	H32 CEMENT AND CONCRETE; I32 Concrete
Contract Number	12323Y, SPR-0004(29)
Report Number	FHWA-NH-RD-12323Y
Availability	National Technical Information Service
URLs	Document: http://www.nh.gov/dot/bureaus/materialsandresearch/research/projects/projects/documents/12323Y_asr2.pdf
TRIS Files	HRIS
Database	TRIS Online