DRYING SHRINKAGE OF CONCRETE AS AFFECTED BY MANY FACTORS
AMONG THE RESULTS PRESENTED, IT IS SHOWN THAT FOR A COMMON GLACIAL GRAVEL AND A STANDARD CEMENT, NEITHER CEMENT CONTENT, NOR GRADATION OF AGGREGATE, NOR DURATION OF PRELIMINARY MOIST CURING HAS MUCH EFFECT ON SHRINKAGE. IT IS INDICATED THAT INVISIBLE CRACKING OF MORTAR BETWEEN AGGREGATE PARTICLES IS COMMON IN CONCRETE SUBJECTED TO DRYING. DIFFERENCES IN EXTENT OF CRACKING OFTEN MAY BE THE DISTINGUISHING FEATURE BETWEEN CONCRETES OF HIGH AND LOW SHRINKAGE. TO TEST THIS HYPOTHESIS, ATTEMPTS WERE MADE TO REDUCE THE TENSILE STRENGTH OF THE MOTAR IN CONCRETE. SMALL AMOUNTS OF GROUND MICA WERE ADDED TO CONCRETE MIXES. SUBSTANTIAL REDUCTIONS IN SHRINKAGE WERE OBTAINED. TYPE OF AGGREGATE IS SHOWN TO HAVE A LARGE EFFECT ON CONCRETE SHRINKAGE. AMONG THE PURE-MINERAL AGGREGATES, DENSE GRADES OF QUARTZ, FELDSPAR, DOLOMITE, AND LIMESTONE ARE OUTSTANDING IN PRODUCING LOW SHRINKAGE. HORNBLENDE AND PYROXENE, WHICH ARE FERROMAGNESIUM SILICATES, PRODUCE CONCRETE OF HIGH SHRINKAGE. AMONG THE AGGREGATES OF MIXED COMPOSITION, SLATE AND SANDSTONE PRODUCE CONCRETE OF VERY HIGH SHRINKAGE. GRANITE FALLS INTERMEDIATE BETWEEN AGGREGATES PRODUCING HIGH AND LOW SHRINKAGE IN ACCORDANCE WITH ITS VARIED CONSTITUENTS. FROM INCOMPLETE STUDIES TO DATE, IT APPEARS THAT THE RIGIDITY, OR MODULUS OF ELASTICITY, OF THE AGGREGATE LARGELY DETERMINES WHETHER OR NOT IT WILL PRODUCE CONCRETE OF HIGH OR LOW SHRINKAGE. /AUTHOR/
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Supplemental Notes:
- Vol 38, ParT 2, PP 419-437, 4 FIG, 6 TAB, 4 REF
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Authors:
- CARLSON, R W
- Publication Date: 1938
Media Info
Subject/Index Terms
- TRT Terms: Admixtures; Aggregate mixtures; Concrete; Cracking; Dense graded aggregates; Dolomite; Drying; Feldspar; Granite; Gravel; Hypothesis testing; Limestone; Mica; Minerals; Modulus of elasticity; Mortar; Quartz; Sandstones; Shrinkage; Slate; Stiffness; Tensile strength
- Uncontrolled Terms: Concrete cracking; Hypothesis
- Old TRIS Terms: Hornblende
- Subject Areas: Data and Information Technology; Highways; Materials;
Filing Info
- Accession Number: 00212658
- Record Type: Publication
- Files: TRIS
- Created Date: Jul 8 1994 12:00AM