SOME CHARACTERISTIC PROPERTIES OF WET STRAINS IN CONCRETE

IN ORDER TO EXAMINE THE DIFFERENCE BETWEEN LABORATORY SHRINKAGE TESTS AND MICRO-OR MACRO-CRACKING OCCURING ON THE SITE, A QUALITATIVE STUDY WAS CARRIED OUT OF PHENOMENA CAUSED BY VARIATIONS IN THE INTERNAL HUMIDITY OF CONCRETE. TWO DIFFICULTIES WERE ENCOUNTERED; THE FIRST WAS THE IRREVERSIBILITY OF THE DEFORMATION/QUANTITY OF LOST WATER RELATION, WHICH CAN BE EXPLAINED IN TWO WAYS: SWELLING PHENOMENA ARE MORE RAPID THAN SHRINKAGE PHENOMENA, AND A CERTAIN QUANTITY OF WATER CAN BE LOST WITHOUT CAUSING SHRINKAGE. THIS DIFFICULTY MUST NOT PREVENT THE STRESSES DUE TO WATER MOVEMENTS FROM BEING TAKEN INTO ACCOUNT IN THE CALCULATIONS OF STRUCTURES. A RECOMMENDATION IS MADE TO START THESE CALCULATIONS BY DEFINING SEVERAL PHYSICAL CHARACTERISTICS SUCH AS THE EFFECTIVE WATER CONTENT OF CONCRETE (WHICH IS PART OF THE TOTAL WATER CONTENT THE LOSS OF WHICH RESULTS IN SHRINKAGE), AND THE CRITICAL WATER CONTENT OF CONCRETE (LIME VALUE AT WHICH THE CEMENT PASTE GEL HAS A MAXIMUM HUMIDITY WITHOUT CONTAINING ANY PORE WATER). FROM THOSE TWO QUANTITIES IT IS POSSIBLE TO DEFINE THE SHRINKAGE AND SWELLING COEFFICIENTS. THE SECOND DIFFICULTY AROSE FROM THE SHRINKAGE OF CONCRETE. TESTS IN WHICH SHRINKAGE AND CREEP ARE COMBINED IN THE SAME SAMPLE SHOW THAT SHRINKAGE STRESSES ARE MARKEDLY LESS THAN THEORETICAL ELASTIC STRESSES WHICH ARE BASED ON THE ASSUMPTION THAT CONCRETE IS NOT SUBJECT TO CREEP. THESE NEW CONCEPTS ARE INTRODUCED IN SOVIET SPECIFICATIONS FOR THE CALCULATION OF CONCRETE AND REINFORCED CONCRETE STRUCTURES. /LCPC/RRL/

• Supplemental Notes:
  • Vol 2, No 3-6, 33 PP, 8 FIG, 1 PHOT, 7 REF
• Authors:
  • Alexandrovsky, S W
  • Desov, A E
• Publication Date: 1968-3

Media Info

• Serial:
  • Matls & Structures, Res & Testing /Fr/

Subject/Index Terms

• TRT Terms: Concrete; Concrete structures; Cracking; Creep; Durability; Humidity; Laboratory tests; Measurement; Moisture content; Reinforced concrete; Shrinkage; Strain (Mechanics); Stresses; Undrained strength; Water; Wave motion
• Uncontrolled Terms: Concrete cracking
• Old TRIS Terms: Concrete creep; Shrinkage tests; Strains
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00213050
• Record Type: Publication
• Source Agency: Road Research Laboratory /UK
• Files: TRIS
• Created Date: Jun 1 1971 12:00AM