Start Date

6-29-2016 4:00 PM

End Date

6-29-2016 6:00 PM

Abstract

Roller compacted concrete (RCC) is frequently used to construct gravity dams, stepped spillways, and to armor earthen embankments for passing extreme floods. Early experience on RCC dam applications in the 1980s showed a tendency for seepage to develop along the lift lines. Therefore, RCC dam designers started including an upstream facing system as a watertight barrier. An alternative facing material that has been used extensively overseas and is starting to gain more widespread acceptance in the United States is Grout Enriched RCC (GERCC). The grout enriched method of face construction has been shown to be less expensive than other facing options, particularly on larger dam projects. However, in the United States, the use of GERCC technology has been fairly limited, primarily due to concern over the material’s freeze-thaw resistance. Achieving cost-effective GERCC air entrainment and consolidation can significantly advance the competitiveness of RCC versus other alternatives. The objective of this project is to develop a grout formulation and construction technique that allows the production of air entrained GERCC. The study includes four phases to systemically achieve this objective: (1) optimizing grout formulation including type and dosage of chemical admixtures, (2) evaluation of small scale laboratory samples of RCC and grout combined in a mixer, (3) evaluation of large scale laboratory samples of RCC and grout combined simulating field construction techniques, and (4) conducting a field trial. The results of Phases 1 and 2 (presented herein) show that when the grout and RCC are combined in a mixer, good freeze-thaw resistance can be achieved. Phases 3 and 4 are currently underway. Through additional research, the project team’s goal is to advance the use of GERCC and promote more cost effective and technically viable construction of gravity dams, stepped spillways, armored earthen embankments and other hydraulic structures in climates subject to freeze-thaw cycles.

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Jun 29th, 4:00 PM Jun 29th, 6:00 PM

Optimization of Air Entrained Grout Enriched Roller Compacted Concrete for Improving Freeze-Thaw Resistance of Hydraulic Structures

Portland, OR

Roller compacted concrete (RCC) is frequently used to construct gravity dams, stepped spillways, and to armor earthen embankments for passing extreme floods. Early experience on RCC dam applications in the 1980s showed a tendency for seepage to develop along the lift lines. Therefore, RCC dam designers started including an upstream facing system as a watertight barrier. An alternative facing material that has been used extensively overseas and is starting to gain more widespread acceptance in the United States is Grout Enriched RCC (GERCC). The grout enriched method of face construction has been shown to be less expensive than other facing options, particularly on larger dam projects. However, in the United States, the use of GERCC technology has been fairly limited, primarily due to concern over the material’s freeze-thaw resistance. Achieving cost-effective GERCC air entrainment and consolidation can significantly advance the competitiveness of RCC versus other alternatives. The objective of this project is to develop a grout formulation and construction technique that allows the production of air entrained GERCC. The study includes four phases to systemically achieve this objective: (1) optimizing grout formulation including type and dosage of chemical admixtures, (2) evaluation of small scale laboratory samples of RCC and grout combined in a mixer, (3) evaluation of large scale laboratory samples of RCC and grout combined simulating field construction techniques, and (4) conducting a field trial. The results of Phases 1 and 2 (presented herein) show that when the grout and RCC are combined in a mixer, good freeze-thaw resistance can be achieved. Phases 3 and 4 are currently underway. Through additional research, the project team’s goal is to advance the use of GERCC and promote more cost effective and technically viable construction of gravity dams, stepped spillways, armored earthen embankments and other hydraulic structures in climates subject to freeze-thaw cycles.