Commonwealth of Pennsylvania PA Test Method No. 106 Department of Transportation 7 Pages 1. SCOPE LABORATORY TESTING SECTION Method of Test for THE MOISTURE-DENSITY RELATIONS OF SOILS (Using a 2.5 kg (5.5-lb.) Rammer and a 305 mm (12") Drop) 1.1 This method of test, which is a modification of AASHTO T-99 is intended for determining the relation between the moisture content and density of soils compacted in a mold of a given size with a 2.5 kg (5.5 lb.) rammer dropped from a height of 305 mm (12"). Method A is used when the test is run on the portion of the soil sample passing the 19.0 mm (3/4") sieve, the material retained on the sieve being discarded. Method B is used when the test is run on a compensated sample of soil passing the 19.0 mm (3/4") sieve, by replacing the amount retained on the sieve with an equal weight of material passing the 19.0 mm (3/4") and retained on the 4.75 mm (No. 4) sieve, taken from the remaining portion of the sample. 2. APPARATUS 2.1 Molds - The mold shall be cylindrical in shape, made of metal, and shall have the capacity and dimensions indicated in Section 2.1.1. It shall have a detachable collar assembly approximately 60.3 mm (2-3/8") in height, to permit preparation of compacted specimens of soil-water mixtures of the desired height and volume. The mold may be of the "split" type, consisting of two half-round sections, or a section of pipe split along one element, which can be securely locked in place to form a cylinder. The mold and collar assembly shall be so constructed that it can be fastened firmly to a detachable base place. 2.1.1 A 102.0 mm (4.0") mold having a capacity of 9.43 x 10-4 ± 8.0 x 10-6 m 3 (1/30 ± 0.0003 cu. ft.), with an internal diameter of 101.60 ± 0.41 mm (4.0 ± 0.016") and a height of 116.43 ± 0.13 mm (4.584 ± 0.005") (Figure 1). 2.1.2 Molds shall be checked for adherence to tolerances annually. Molds may remain in use after continued service provided the original tolerances (Section 2.1.1) are not exceeded by more than 50 percent. Molds meeting this stipulation shall be calibrated for volume according to Section 8 (Calibration of Measure) of AASHTO T-19, for Unit Mass of Aggregates, and the found volume used in all subsequent calculations. 2.2 Rammer - A manually operated metal rammer 50.8 mm (2") in diameter having a flat circular face and weighing 2.5 kg (5.5 lb.). The rammer shall be equipped with a suitable arrangement to control the height of drop to a free fall of 305 mm (12") above the elevation of the soil. 2.3 Sample Extruder (optional) - A jack, lever, frame or other device adapted for the purpose of extruding compacted specimens from the mold.
Page 2 2.4 Balances - A balance or scale of at least 10 kg (25 lb.) capacity sensitive to 5 g (0.01 lb), and a balance of at least 1000 g (2.2 lbs.) capacity sensitive to 0.1 g (0.002 lbs). 2.5 Drying Equipment - Stove, oven, hot plate or other suitable equipment for drying moisture content samples. 2.6 Straight Edge - A steel straightedge 300 mm (12") in length and having one beveled edge. 2.7 Sieves - 50.0 mm, 19.0 mm, and 4.75 mm (2", 3/4", and No. 4) sieves conforming to the requirements of the Specifications for Sieves for Testing Purposes, AASHTO M-92. 2.8 Mixing Tools - Miscellaneous tools such as mixing pan, spoon, trowel, spatula, etc., or a suitable mechanical device for thoroughly mixing the sample of soil with increments of water. 3. METHOD A 3.1 Sample 3.1.1 If the soil sample is damp when received from the field, dry it until it becomes friable under a trowel. Drying may be in air or by use of drying apparatus such that the temperature of the sample does not exceed 60 o C (140 o F). Then thoroughly break up the aggregations in such a manner as to avoid reducing the natural size of the individual particles. Note - When the material is granulated slag, the sample should be dried to approximately 4 percentage points below optimum moisture content. 3.1.2 Sieve an adequate quantity of the representative pulverized soil over the 19.0 mm (3/4") sieve. Discard the coarse material, if any, retained on the 19.0 mm (3/4") sieve. 3.1.3 Select a representative sample, weighing approximately 5.0 kg (12 lb.), or more, of the soil prepared as described in Sections 3.1.1 and 3.1.2. 4. METHOD B 4.1 Sample 4.1.1 If the soil sample is damp when received from the field, dry it until it becomes friable under a trowel. Drying may be in air or by use of a drying apparatus such that the temperature of the sample does not exceed 60ºC (140ºF). Then thoroughly break up the aggregations in such a manner as to avoid reducing the natural size of individual particles. Note - When the material is granulated slag, the sample should be dried to approximately 4 percentage points below optimum moisture content.
Page 3 4.1.2 Sieve an adequate quantity of the representative pulverized soil over a 19.0 mm (3/4") sieve. Discard any large oversized pieces. Weigh the material retained on the 19.0 mm (3/4") sieve and replace it with an equal mass of material passing the 19.0 mm (3/4") sieve and retained on the 4.75 mm (No. 4) sieve. Take the material for replacement from the remaining portion of the sample. 4.1.3 Select a representative sample, weighing approximately 5 kg (12 lb) of the soil prepared as described in Sections 4.1.1 and 4.1.2.
Page 4 5. PROCEDURE 5.1 Thoroughly mix the selected representative sample with sufficient water to dampen it to approximately 4 percentage points below optimum moisture content. 5.2 Form a specimen by compacting the prepared soil in the 102.0 mm (4") mold (with collar attached) in three equal layers to give a total compacted depth of about 125.0 mm (5"). Compact each layer by using 25 uniformly distributed blows from the rammer, dropping free from a height of 305.0 mm (12") above the elevation of the soil when a sleeve type rammer is used, or from 305.0 mm (12") above the approximate elevation of each finally compacted layer when a stationary mounted type of rammer is used. During compaction, the mold shall rest on a uniform, rigid foundation, such as is provided by a cube of concrete weighing not less than 90 kg (200 lb). Following compaction, remove the extension collar, and carefully trim the compacted soil even with the top of the mold by means of the straightedge. Holes developed in the surface by removal of coarse material shall be patched with smaller sized material. Weigh the mold and moist soil. Multiply the mass of the compacted specimen and mold, minus the mass of the mold, by 1059.32 (30), and record the result as the wet mass per cubic meter (foot) of the compacted soil. 5.3 Remove the material from the mold and slice vertically through the center. Take a representative sample of the material from one of the cut faces, weigh immediately, and dry in an oven at 110 ± 5ºC (230 ± 9ºF ) for at least 12 hr., or to constant weight, on a hot plate or in accordance with PTM 123 to determine the moisture content. The moisture content sample shall weigh not less than 200 g (0.5 lbs). 5.4 Thoroughly break up the remainder of the material until it will pass a 19.0 mm (3/4") sieve and 90 percent of the soil aggregations will pass a 4.75 mm (No 4) sieve as judged by eye, and add this material to the remaining portion of the sample being tested. Add water in sufficient amounts to increase the moisture content of the soil sample by one or two percentage points, and repeat the above procedure for each increment of water added. Continue this series of determinations until there is either a decrease or no change in the wet mass per cubic meter (foot) of the compacted soil. NOTE - Another procedure is by the use of separate samples. In instances where the soil material is fragile in character and will be reduced significantly in grain size due to repeated compaction, and in cases where the soil is heavy-textured clayey material into which it is difficult to incorporate water, a separate and new sample shall be used in each compaction test. In these cases, separate samples shall be thoroughly mixed with amounts of water sufficient to cause the moisture contents of the samples to vary by approximately two percentage points. The moisture contents selected shall bracket the optimum moisture content, thus providing samples which, when compacted, will increase in mass to the maximum density and then decrease in mass.
Page 5 6. CALCULATIONS AND REPORT 6.1 Calculations 6.1.1 Calculate the moisture content and the dry mass of the soil as compacted for each trial, as follows: M W W = W P 1 2 X 2 100 and Dw D = X 100 M +100 Where: M = Percentage of moisture in the specimen, based on dry mass W 1 = Moist mass of sample including pan, in grams W 2 = Dry mass of sample including pan, in grams P = Mass of pan in grams D W = Wet density of compacted soil specimen, in kilograms per cubic meter (pounds per cubic foot) D = Dry density of compacted soil specimen, in kilograms per cubic meter (pounds per cubic foot) 7. MOISTURE-DENSITY RELATIONSHIP 7.1 The calculations in Section 6.1.1 shall be made to determine the moisture content and corresponding oven-dry mass (density) for each of the compacted soil samples. The ovendry masses per cubic meter (foot) (densities) of the soil shall be plotted as ordinates and corresponding moisture contents as abscissas. 7.2 Optimum Moisture Content - When the densities and corresponding moisture contents for the soil have been determined and plotted as indicated in Section 7.1, it will be found that by connecting the plotted points with a smooth line, a curve is produced. The moisture content corresponding to the peak of the curve shall be termed the "optimum moisture content" of the soil under the above compaction. The smooth curve should be a free-hand approximation of a parabola. The use of a straightedge in drawing the curve is discouraged. A zero air voids line may be added to the graph only when it is appropriate to the measured specific gravity of the sample. 7.3 Maximum Density - The oven-dry mass per cubic meter (foot) of the soil at optimum moisture content shall be termed "maximum density" under the above compaction.
Page 6 8. REPORT 8.1 The report shall include the following: 9. REFERENCES 8.1.1 The optimum moisture content 8.1.2 The maximum density 8.1.3 Indicate if Method A or Method B was used AASHTO T-99 ASTM D-698 PENNDOT Bulletin 39
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