WATER-REDUCING RETARDERS FOR CONCRETE--PHYSICAL TESTS

A BLEND OF EQUAL PARTS BY WEIGHT OF FOUR BRANDS OF TYPE I CEMENT WAS USED FOR ALL CONCRETES IN THIS INVESTIGATION OF TWENTY-FIVE RETARDERS. THE CHEMICAL COMPOSITION AND PHYSICAL PROPERTIES OF EACH BRAND OF RETARDER ARE SHOWN IN A TABLE. THE AIR ENTRAINING ADMIXTURE USED WAS AN AQUEOUS SOLUTION OF NEUTRALIZED VINSOL RESIN. THE SOLUTION CONTAINED FIFTEEN PERCENT OF SOLIDS WHEN CALCULATED AS A RESIDUE DRIED AT 105 C, AND THE RATIO OF SODIUM HYDROXIDE TO VINSOL RESIN WAS ONE TO 6.4 PARTS BY WEIGHT. MIXING WAS DONE IN AN OPEN-PAN TYPE LANCASTER MIXER WITH A RATED CAPACITY OF ONE AND 3/4 CUBIC FEET. ALL SPECIMENS FOR STANDARD STRENGTH TEST WERE CURED UNDER WET BURLAP WHILE IN THE MOLDS IN THE MIXING ROOM. TESTS ON THE PLASTIC CONCRETE FOR SLUMP, UNIT WEIGHT, AND AIR CONTENT WERE MADE IN ACCORDANCE WITH AASHO STANDARD METHODS. DETERMINATION OF THE RETARDATION OF THE SET OF CONCRETE WAS MADE BY THE PROCTOR PENETRATION METHOD AND BY THE BOND PIN PULLOUT METHOD. THE EFFECT OF RETARDERS ON THE CONCRETE ARE DISCUSSED IN TERMS OF: (1) RETARDATION OF SETTING TIME, (2) WATER CONTENT AND AIR-ENTRAINMENT, (3) STRENGTH, (4) DURABILITY, AND (5) VOLUME CHANGE. ADDITIONAL TESTS SUCH AS THE EFFECT OF OVERDOSAGE OF RETARDERS, RETARDATION AND STRENGTH AT ELEVATED TEMPERATURE, MODULUS OF ELASTICITY, DELAYED VIBRATION, DENSITY AND ABSORPTION, AND TEMPERATURE RISE, ARE ALSO DISCUSSED. THE EFFECT OF ADMIXTURES ON TIME OF RETARDATION AND THE EFFECT OF RETARDERS IN CONCRETE ARE SHOWN IN TABLES. RESULTS OF THE COMPRESSIVE STRENGTH AND FLEXURAL STRENGTH TESTS ARE SHOWN IN AVERAGE VALUES. STUDIES OF THE DIFFERENT GROUPS OF RETARDERS SHOW THAT CONCRETES PREPARED WITH THE CALCIUM LIGNOSULFONATE RETARDER HAD LOWER FLEXURAL STRENGTH THAN THOSE PREPARED WITH THE CARBOHYDRATE, THE AMMONIUM AND LIGNOSULFONATES AND THE ORGANIC ACIDS. IN THE FLEXURAL TESTS, THE CONCRETE HAD STRENGTHS LOWER THAN THOSE OF THE REFERENCE CONCRETE, BUT WITH RESPECT TO THE OTHER RETARDED CONCRETES, THE STRENGTH WERE REDUCED BUT SLIGHTLY. IT APPEARS PROBABLE IN THE ACCEPTANCE TESTING OF RETARDERS, CONSIDERATION SHOULD BE GIVEN TO THE INDIVIDUAL RETARDERS AND NOT ASSUME THAT ALL RETARDERS OF A GIVEN TYPE WILL AFFECT CONCRETE IN THE SAME MANNER. FREEZE AND THAW TESTS INDICATE SIGNIFICANCE IN ACCEPTABLE OR QUALIFICATION TESTS OF A RETARDER WHICH REQUIRES NO AIR-ENTRAINING ADMIXTURE TO OBTAIN THE SPECIFIED AIR CONTENT IN CONCRETE. TESTS INDICATE THAT DELAYED VIBRATION OF CONCRETE AT 5 1/2 HOURS AFTER PLACING WAS BENEFICIAL TO THE COMPRESSIVE STRENGTH. FOR CONCRETE OF EQUAL CEMENT CONTENT AND EQUAL SLUMP, ALL RETARDERS TESTED PERMITTED REDUCTIONS OF THE WATER CONTENT. THE CHEMICAL COMPOSITION OF THE RETARDERS GENERALLY AFFECTED THE REDUCTION OF WATER, ELEVATED TEMPERATURE TESTS SHOWED THAT ONLY ONE RETARDER CAUSED CONCRETE TO HAVE A MAXIMUM RISE IN TEMPERATURE SIGNIFICANTLY HIGHER THAN THAT OF NON- RETARDED CONCRETE MADE AND STORED AT 73 F. IN TESTS OF MORTAR SPECIMENS MADE AND STORED AT 90F, ONLY ONE RETARDER CAUSED THE MAXIMUM RISE IN TEMPERATURE TO EXCEED THAT OF MORTAR PREPARED WITHOUT A RETARDER.

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  • Supplemental Notes:
    • No 31, No 6, PP 136-139, 142-152, 154, 12 FIG, 13 TAB, 3 REF
  • Authors:
    • Grieb, W E
    • WERNER, G
    • Woolf, D O
  • Publication Date: 1961-2

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  • Accession Number: 00212703
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 21 1994 12:00AM