CURRENT PROBLEMS IN SHRINKAGE OF CONCRETE AS AFFECTED BY CEMENT PASTE
THE MECHANISM OF SHRINKAGE IS REVIEWED. SHRINKAGE IS ONE OF THE MOST IMPORTANT PROPERTIES OF CONCRETE AS IT IS RESPONSIBLE, DIRECTLY OR INDIRECTLY, FOR CRACKING IN A GREAT MANY SITUATIONS. DRYING SHRINKAGE IS USUALLY DEFINED AS A CHANGE IN VOLUME ON LOSS OF WATER, BUT IF CEMENT PASTE IS SUBJECTED TO A CHANGE IN TEMPERATURE, WITHOUT ANY MOVEMENT OF WATER, SHRINKAGE OR SWELLING CAN TAKE PLACE IN ADDITION TO THE MOVEMENT CAUSED BY THERMAL EXPANSION. THE FOLLOWING INFLUENCES ON SHRINKAGE ARE DISCUSSED: (1) ADDED WATER, (2) WATER MOVEMENT IN AGGREGATE, (3) FINENESS OF CEMENT, (4) ADDITIVES, (5) IRREVERSIBLE SHRINKAGE, (6) SHRINKAGE-CREEP INTERACTION, (7) TEMPERATURE, (8) SIZE OF SPECIMEN, AND (9) CARBONATION SHRINKAGE. THE SURVEY SHOWS THAT THE MAIN PROBLEMS IN SHRINKAGE NOT COMPLETELY RESOLVED ARE: (1) THE EXACT MECHANISM OF SHRINKAGE WITH PARTICULAR REFERENCE TO THE RELATION BETWEEN LOSS OF WATER AND STRAIN, (2) THE ROLL OF INTRACRYSTALLINE WATER IN SHRINKAGE AND THE RELATED PROBLEM OF STRUCTURE OF TOBERMORITE, (3) THE CONDITIONS OF STEAM CURING WHICH RESULT IN DIFFERENT SHRINKAGE THAN THAT OF NORMALLY CURED PASTE, (4) INFLUENCE OF TEMPERATURE ON SHRINKAGE AND THE MECHANISM THROUGH WHICH WATER IS EXPELLED FROM THE HEATED BUT SEALED PART OF THE CONCRETE TO THE EXPOSED, COOL SURFACE, (5) FACTORS IN THE IRREVERSIBLE PART OF SHRINKAGE AND THE HYSTERESIS OF THE SOCALLED IRREVERSIBLE PART, (6) MECHANISM THROUGH WHICH THE ABSORPTION OF AGGREGATE AFFECTS THE SHRINKAGE OF THE CONCRETE, (7) THE EFFECT ON SHRINKAGE OF THE WATER CEMENT RATIO OF THE PASTE AND THE WATER CONTENT OF THE CONCRETE, (8) THE INFLUENCE OF FINENESS OF CEMENT ON SHRINKAGE AND CRACKING OF CONCRETE, AS DISTINCT FROM SHRINKAGE OF NEAT CEMENT PASTE, (9) INFLUENCE OF THE LENGTH OF CURING ON MAGNITUDE OF SHRINKAGE AND DEVELOPMENT OF CRACKING, (10) THE SHAPE OF THE SHRINKAGE-TIME CURVE FOR DIFFERENT MIXES AND CONDITIONS, (11) THE SHRINKAGE-CREEP INTERACTION, AND (12) THE MECHANISM OF CARBONATION SHRINKAGE.
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Supplemental Notes:
- Vol63, No 748, PP 1223-1231, 36 REF
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Authors:
- Neville, A M
- Publication Date: 1968-11
Media Info
Subject/Index Terms
- TRT Terms: Additives; Carbonization; Cement; Concrete; Cracking; Drying; Fineness; Moisture content; Pastes; Shrinkage; Steam curing; Swelling; Temperature; Thermal expansion; Tobermorite; Volume changes; Water cement ratio
- Uncontrolled Terms: Concrete cracking
- Subject Areas: Highways; Materials;
Filing Info
- Accession Number: 00213356
- Record Type: Publication
- Files: TRIS
- Created Date: Jun 2 1994 12:00AM