Concrete growth problems and remedial measures at TVA projects
Most concrete structures are designed and detailed to provide for a volume decrease without excessive cracking. Occasionally, however, a concrete structure exhibits a long-term increase in volume termed concrete growth. Concrete growth may result from a variety of reactions, such as the hydration of unstable oxides included in the concrete mix, or the oxidation of minerals or from an outside attack of sulfates. The most important reaction creating concrete growth is that between minor alkali hydroxides from cement and the concrete aggregates. Two distinctly different harmful reactions have been recognized: the alkali-silicate and alkali-carbonate reactions. Concrete deteriorating from an alkali-aggregate reaction, regardless of the type, develops an obvious network of cracks called pattern or map cracking. These alkali-aggregate reactions and their accompanying concrete growth have presented numerous problems at TVA's Fontana Dam, Chickamauga Dam and lock, and Hiwassee Dam. Much has been learned about alkali-aggregate reaction since 1940. Most harmful reactions can now be prevented in proposed structures by interpreting the results of standard test methods. It is not possible, however, in existing structures to determine how far the growth phenomenon has progressed, how long the effects will have to be dealt with, or what the future effects will be. A program of close surveillance and monitoring is maintained at these projects, and problems are dealt with as they arise.
- Research Organization:
- Tennessee Valley Authority, Knoxville (USA). Div. of Engineering
- OSTI ID:
- 6221983
- Report Number(s):
- TVA/OP/EN/DES-85/10; CONF-8411147-1; ON: DE85900675
- Resource Relation:
- Conference: Corps of Engineers structural conference, Pittsburgh, PA, USA, 15 Nov 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
13 HYDRO ENERGY
CONCRETES
CHEMICAL REACTIONS
CRACK PROPAGATION
DAMS
MATERIALS
MONITORING
CARBONATES
POTASSIUM HYDROXIDES
SILICATES
SODIUM HYDROXIDES
TENNESSEE VALLEY AUTHORITY
ALKALI METAL COMPOUNDS
BUILDING MATERIALS
CARBON COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXIDES
NATIONAL ORGANIZATIONS
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
SILICON COMPOUNDS
SODIUM COMPOUNDS
US ORGANIZATIONS
360604* - Materials- Corrosion
Erosion
& Degradation
130000 - Hydro Energy