Tex-113-E, Laboratory Compaction Characteristics and Moisture- Density Relationship of Base Materials

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1 Characteristics and Moisture- Density Overview Effective Date: August 1999 October This method determines the relationship between water content and the dry unit mass (density) of base materials. The base materials are compacted in a mold with a rammer dropped from a set height (10 lb. hammer, 18 inch drop, 25 blows/layer). The test is performed on prepared materials passing the 45 mm (1-3/4 in.) sieve. Follow Test Method "Tex-114-E, Laboratory Compaction Characteristics and Moisture-Density Relationship of Subgrade & Embankment Soils," to determine moisture-density relationships of untreated subgrade and embankment soils. Definitions The following terms and definitions are referenced in this test method: maximum dry density (DA) - Maximum dry density is the maximum value obtained by the compaction curve using the specified compactive effort. optimum water content (WO) - Optimum water content is the water content at which the soil can be compacted to the maximum dry density. compactive effort (C.E.). - Compactive effort is the total energy, expressed as kilo-newton-meters per cubic meter (foot-pounds per cubic inch) used to compact the specimen. Compactive effort is calculated as follows: Ht. of Drop( m or ft ) Wt. of Hammer( kn or lb ) # Drops # Layers CE.. = 3 3 Volume of Mold ( m or in ) This procedure requires ft.-lb./in 3. NOTE: In the metric system the units for weight and mass are not the same. In order to convert the mass of the hammer to the metric "weight" you must multiply the mass by the force of gravity, g, which in the metric system is 9.8 m/sec 2. The resulting unit is a Newton. Divide that number by 1000 to get kilo-newtons (kn). Apparatus The following apparatus is required: Manual of Testing Procedures 1 08/99 10/04

2 automatic tamper (compaction) device with base plate to hold mm (6 in.) inside diameter (I.D.) forming molds, equipped with a 4.55 ± 0.01 kg (10 ± 0.02 lb.) rammer and adjustable height of fall Striking face of the rammer should conform to a 43 ± 2 segment of a 74 ± 2.5 mm (2.9 ± 0.1 in.) radius circle. The base plate of the tamper shall be secured to a rigid foundation such as a concrete block with a mass of not less than 91 kg (200 lbs.). An alternate foundation support, such as a rigid stand or table, may be used if the D A produced is within 2% of that produced by an automatic tamper bolted to a concrete floor. a rigid metal compaction mold having a mm, or mm (6 in., +1/16 or -1/64 in.) I.D. and ± 1.6 mm (8.5 ± 1/16 in.) height with removable collar a metal stand with a set of standard spacer blocks and a micrometer dial assembly, with 50 mm (2 in.) travel, for determining height of specimens. Spacer blocks 25.4, 101.6, and mm (1, 4, 6 and 11 in.) accurate to mm (0.001 in.). balance with a minimum capacity of 15 kg (35 lb.), accurate and readable to 0.5 g or 0.1% of the test mass, whichever is greater extra base plate secured on a rigid stand to hold the forming mold hydraulic press to extrude compacted specimens from mold drying oven maintained at 110 ± 5 C (230 ± 9 F) metal pans, wide and shallow for mixing and drying materials circular porous stones slightly less than mm (6 in.) in diameter and 51 mm (2 in.) high a supply of small tools including a 1.8 to 2.3 kg (4 to 5 lb.) rawhide hammer, 0.5 to 0.9 kg (1 to 2 lb.) plastic mallet, level, finishing tool and others. Calibrating Equipment The following steps are necessary to calibrate equipment: Measure the diameter of the mold at the ends and at several intermediate points, using a micrometer caliper and micrometer dial. Calculate an average diameter, d avg, in mm (in.). Calculate the cross sectional area of the mold: A = ( d )/ 4, mm ( in ) x avg Manual of Testing Procedures 2 08/99 10/04

3 Calculate the volume, in m 3 (ft 3 ) for 1 mm (0.04 in.) of height of the mold: Volume per mm = A / 10, m / mm ( Volume per in. = A / 1728, ft / in.) x x Weigh and record the mass of the mold, W m, K g (lb.). Preparing Sample Prepare the material according to 'Part II, Preparing Samples for Compaction and Triaxial Tests' of Test Method "Tex-101-E, Preparing Soil and Flexible Base Materials for Testing." NOTE: For wetted stabilized materials taken from the roadway, see appropriate test method for preparation procedure for specification compliance, density, and/or strength. Cement Stabilization: Test Method "Tex-120-E, Soil-Cement Testing" Lime Stabilization: Test Method "Tex-121-E, Soil-Lime Testing" Lime-Fly Ash Stabilization: Test Method "Tex-127-E, Lime-Fly Ash Compressive Strength Test Methods" Materials Difficult to Compact Materials that are difficult to compact are an exception and require special attachments to the compaction apparatus A 4.54 kg (10 lb.) rammer with twin striking face, a drop height of mm (18 in.) A 12.7 mm (0.5 in.) thick neoprene pad (Type A Shore durometer of 65 ± 3). The mm (6 in.) diameter neoprene pad should just slide into the mold on top of the sand layer and will divert some of the impact to vibrations. Compact the material in eight 25.4 mm (1 in.) layers using the neoprene pad and 100 ram blows of the 4.55 kg (10 lb.) rammer for each layer. The rammer with a twin striking face should be used when the material, wetted to slightly below optimum water content, mixed thoroughly and molded in two 51 mm (2 in.) lifts, is sheared or torn by the ram in excess of 25.4 mm (1 in.) on the last (50th) blow. Manual of Testing Procedures 3 08/99 10/04

4 Procedure The following table lists the steps necessary to determine the relationship between water content and the dry unit mass (density) of base materials. Determining the Relationship between Water Content and the Dry Unit Mass (Density) of Base Materials Step Action 1 Obtain a representative sample of prepared material and determine the percent hygroscopic moisture of the sample. 2 Estimate the mass of air dry material that will fill the mold when wetted and compacted. 3 Using this estimated mass and the percentages of the various sizes of particles obtained in the preparation of the sample, compute the cumulative masses for each size to be combined to make a specimen. NOTE: The compacted material will not be trimmed with a straight edge and is not expected to completely fill the mold after compaction. 4 Weigh out several samples as calculated in Step 2. 5 Estimate the percent moisture at optimum. 6 Start the water content of the first specimen at 2 to 4% below this estimate and adjust water content of the other specimens in approximately 2% increments. 7 Calculate the amount of water to be added based on the mass of the air-dried material. 8 Weigh out this amount of water in a tared sprinkling jar. 9 Place the total sample in the mixing pan, mix thoroughly and wet with all of the mixing water by sprinkling water in increments onto the sample during mixing. 10 Mix thoroughly breaking up the soil lumps. Do not break any aggregate particles in the sample. 11 Turn the wet material over with the mixing trowel to allow the aggregate particles to absorb water. 12 After thoroughly mixing, weigh the sample and cover the mixture to prevent loss of moisture by evaporation. 13 Allow the wetted samples to stand for 12 hours before compaction. A standing time of more than 12 hours may be required for materials with a PI of 12 or greater. When the PI is less than 12, the standing time may be reduced to not less than 4 hours. Split or referee samples should stand the full term. 14 Prior to compaction, weigh the sample and replace any evaporated water and thoroughly mix each specimen to ensure even distribution of water throughout the sample. 15 Determine the mass of the compaction mold and record on the 'M/D & Triaxial Test Worksheet,' Form Estimate the mass needed for one 51 mm (2 in.) layer of compacted material (approximately one-fourth of the total material for this specimen.) 17 Separate the coarse aggregate into the quadrants of the pan in equal and representative portions for each layer. 18 Weigh out material for the first layer. With a spatula, separate the aggregate from the fines. 19 Place some loose fines in the bottom 13 mm (0.5 in.) of the mold and level with a spatula. 20 Hand place any aggregates retained on the 22.6 mm (7/8 in.) sieve for maximum density. With a spatula or hand, separate the intermediate aggregates and fines. Add a small amount of fines to fill voids between the coarse aggregates. 21 From the top of the mold, use a scoop to place all material passing the 22.6 mm (7/8 in.) sieve, saving some fines. Manual of Testing Procedures 4 08/99 10/04

5 Determining the Relationship between Water Content and the Dry Unit Mass (Density) of Base Materials Step Action Use a spatula to arrange aggregate so as to minimize contact with the mold. Finish the lift with the addition of the remaining fines from this layer. 22 Use a spatula or similar hand tool to spade around the inside of the mold to allow some of the fines to fill any cavities around the edge before compacting the layer. 23 The finishing tool may be used to level the surface of the sample before compacting. 24 Do not push this layer down by hand or other means than that described above. 25 Compact the layer by applying 50 ram blows of the 4.55 kg (10 lb.) rammer from a height of mm (18 in.). 26 Stop the compactor as frequently as necessary to clean the ram face of sticking material. 27 Use the sample mass and compacted thickness of the first layer to adjust the mass and thickness of the subsequent lifts. 28 After the fourth layer has been compacted, fasten the mold containing the material on top of the extra base plate. 29 Finish the specimen to an even and level top surface by means of the various hand tools, such as a putty knife, a plastic mallet, and a circular plate with a smooth surface. 30 Use the small level to check the surface of the specimen so that it will be plane and level with the top of the forming mold. NOTE: Do not trim the specimen. 31 When the surface is level, apply a schedule of blows to the top of the finishing tool. 32 Use five to ten light blows of the 0.5 to 0.9 kg (1 to 2 lb.) plastic mallet followed by five firm blows of the 1.8 to 2.3 kg (4 to 5 lb.) rawhide hammer to finish the surface of the compacted specimen. The height of the finished specimen should be ± 3 mm (8 ± 1/8 in.). 33 Remove mold from the base plate. 34 Weigh the specimen in the mold to the nearest estimated 0.5 g and measure the sample height by means of the micrometer dial assembly to the nearest 0.03 mm (0.001 in.) 35 Record data on the 'M/D & Triaxial Test Worksheet,' Form Carefully center the specimen over a porous stone and place in the hydraulic press to extrude the specimen from the mold. 37 Remove the stones from the specimen over a tared flat drying pan. 38 Break up the specimen and place the identification tag with the loose material in the drying pan. 39 Obtain the mass of the drying pan and wet sample. Weigh and record to 0.5 g. 40 Place the drying pan with wet material in an oven at a temperature of 110 C (230 F) until a constant mass has been reached. 41 Record the mass of the oven-dried material to the nearest 0.5 g under 'Calculations.' 42 After compacting the first two or three specimens, construct the M/D curve to aid in evaluating the shape of the curve. If a well-defined compaction curve is not obtained, it may be necessary to adjust the water content of other prepared samples by adding additional water or air-drying to obtain a well-defined M/D curve. To obtain a well-defined compaction curve, provide two water content percentages on both sides of optimum. NOTE: Compacted sample(s) should not be reused for preparation of other compaction specimens. Manual of Testing Procedures 5 08/99 10/04

6 Precautions Please note that in Steps of the table 'Determining the Relationship between Water Content and the Dry Unit Mass (Density) of Base Materials,' when placing material in the mold, larger aggregates should be placed well down near the bottom of the layer in their most stable position. Usually, aggregates of 19.0 mm (3/4 in.) in size or larger do not move down into the layer during the action of the ram. The finer sizes on top will beat down between the larger aggregates, but care and judgment must be exercised in order to prevent creating excessive voids in the specimen. The finished top should be as free as possible from large aggregates. Calculations Use the following equations to determine the volume, the percent water content, and the dry density of each specimen. Calculate the wet density of the compacted specimens, kg/m 3 (lbs/ft 3 ): D = ( W W )/ V WET T M M Where: W T = mass of the mold and the compacted sample, kg (lb.) W M = mass of the mold, kg (lb.) V M = volume of the mold, m 3 (ft 3 ). Calculate the percent water content: WC = 100[( M M ) / M ] W D D Where: M W = wet mass of the sample, kg (lb.) M D = dry mass of the sample, kg (lb.). Calculate the dry density of the compacted specimens: D = 100 D /( WC) DRY WET Where: WC = water content of the compacted specimen, % (includes hygroscopic moisture) Calculate the zero air voids density: Manual of Testing Procedures 6 08/99 10/04

7 DZAV = ( Specific Gravity )/ { 1+ [ Specific Gravity (% MC / 100 )]} Where the specific gravity is not known, a value of 2.65 may be used as an average value. Computer Program The following worksheet (TEX113) may be used to calculate. Test Record Record test data on the 'M/D & Triaxial Test Worksheet,' Form Graph Plot the dry density against the percent of molding moisture on 'Plot of Sample Moisture-Density Curve.' Figure Error! No text of specified style in document. 1. Plot of Sample Moisture- Density Curve. Manual of Testing Procedures 7 08/99 10/04

8 General Notes The zero percent air void line can be used as an aid in drawing the moisture-density curve. For materials containing more than approximately 10% fines, the wet leg of the moisture-density curve generally parallels with the zero air void curve. Theoretically, the moisture-density curve cannot plot to the right of the zero percent air void curve. If it does, there is an error in specific gravity, in measurement, in calculation, in sample preparation, or in plotting. When determining the M/D curve for stabilized subgrade and base materials the following options are recommended: Recommended Amounts of Lime for Stabilization of Subgrades and Bases, (Fig121-1) in Test Method "Tex-121-E, Soil-Lime Testing" or 'Determining Stabilization Ability of Lime by Soil ph' of Test Method "Tex- 121-E, Soil-Lime Testing." Reporting Test Results Report the: Maximum Dry Density (D A ) to the nearest kg/m 3 (0.1 lb/ft 3 ). Optimum Water Content to the nearest 0.1%. Manual of Testing Procedures 8 08/99 10/04