THE EFFECT OF ADMIXTURES ON LAYERED SYSTEMS CONSTRUCTED WITH SOIL-CEMENT

A METHOD FOR THE ANALYSIS AND DESIGN OF A LAYERED SOIL- CEMENT SYSTEM WAS DEVELOPED, UTILIZING UNCONFINED COMPRESSIVE STRENGTH SPECIMENS PREPARED IN TWO 2-INCH LAYER, WITH A 20-DEGREE SLOPE AT THE TOP OF THE BOTTOM LAYER, TO WHICH A SET RETARDING ADDITIVE WAS ADDED. VARIOUS DELAYS BETWEEN PLACEMENT OF LAYERS AND VARIOUS CURING PERIODS WERE USED FOR EACH SOIL-CEMENT-RETARDER COMBINATION. OVER 2,000 SPECIMENS MOLDED WITH 26 LOUISIANA SOILS WERE TESTED. SOIL MECHANICS AND SOIL STABILIZATION THEORY, DEVELOPED BY OTHERS, IS DISCUSSED TO PROVE THE NEED FOR BONDING THE LAYERS. LITERATURE INDICATED THAT THE BOND MUST BE CAPABLE OF TRANSFERRING 70 PERCENT OF THE APPLIED PRESSURE TO THE LOWER LAYER, TO PREVENT FAILURE AT THE INTERFACE. THE AUTHORS ILLUSTRATE, BY A NUMERICAL EXAMPLE, THAT THE STRESS AT THE INTERFACE FOR PERFECTLY BONDED LAYERS IS APPROXIMATELY 1/3 THE STRESS DEVELOPED AT THE INTERFACE FOR UNBONDED LAYERS /FRICTIONLESS INTERFACE/. SHEAR STRENGTHS COMPUTED FROM UNCONFINED COMPRESSIVE STRENGTH DATA BY USING MOHRS CIRCLE OF STRESS DIAGRAM SHOW THAT THE SET RETARDING ADDITIVE PRODUCED BOND BETWEEN LAYERS AND INCREASED SHEAR STRENGTH /FROM 70 TO 180 PERCENT/ FOR A CERTAIN GROUP OF SOILS BUT NOT FOR THOSE IN ANOTHER GROUP. IDENTIFICATION OF A SOIL AS BELONGING TO A SPECIFIC GROUP WAS OBTAINED BY PLOTTING FOR EACH SOIL THE GAIN IN SHEAR STRENGTH AGAINST A SHEAR FACTOR /DIFINED AS PERCENT CLAY/ PERCENT SILT PLUS PERCENT SAND/. THE REPORT PROPOSES THAT WHETHER AN ADDITIVE WILL PRODUCE BENDING IN LAYERS OF SOIL- CEMENT PREPARED FROM A GIVEN SOIL CON BE DETERMINED FROM A GRADATION TEST AND THE SOILS SHEAR FACTOR. THE AUTHORS CONCLUDE' /1/ BOND BETWEEN SOIL-CEMENT LAYERS IS NECESSARY WHEN THE THICKNESS OF THE UPPER LAYER IS LESS THAN 2 1/2 TIMES THE RADIUS OF THE LOAD CONTACT AREA, /2/ CALCIUM LIGNOSULFONATE AND HYDROXYLATED CARBOXYLIC ACID ARE EFFECTIVE IN CREATING BOND BETWEEN SOIL-CEMENT LAYERS, AND /3/ ADMIXTURES GENERALLY IMPROVE THE DURABILITY OF THE STABILIZED MATERIAL. THE AUTHORS RECOMMEND THE ADDITION OF SET RETARDERS TO THE LOWER LAYER OF A TWO LAYERED SYSTEM AT A CONCENTRATION OF 0.25 POUNDS PER BAG OF PORTLAND CEMENT WITH THE TIME LAPSE BETWEEN MIXING OF THE FIRST LAYER AND PLACING OF THE SECOND LAYER NOT TO EXCEED 7 HOURS.

  • Supplemental Notes:
    • Hpr 1/3/, NO 61-9S,1965
  • Corporate Authors:

    Louisiana State University and Agriculture & Mechanical College, Baton Rouge

    Baton Rouge, LA  United States  70803
  • Authors:
    • Arman, A
    • Dantin, T J
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00230565
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Aug 15 2004 2:18AM