Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft³ (600 kN-m/m³))

Importancia y uso:

5.1 Soil placed as engineering fill (embankments, foundation pads, road bases) is compacted to a dense state to obtain satisfactory engineering properties such as, shear strength, compressibility, or permeability. In addition, foundation soils are often compacted to improve their engineering properties. Laboratory compaction tests provide the basis for determining the percent compaction and molding water content needed to achieve the required engineering properties, and for controlling construction to assure that the required compaction and water contents are achieved.

5.2 During design of an engineered fill, shear, consolidation, permeability, or other tests require preparation of test specimens by compacting at some molding water content to some unit weight. It is common practice to first determine the optimum water content (w_opt) and maximum dry unit weight (γ_d,max) by means of a compaction test. Test specimens are compacted at a selected molding water content (w), either wet or dry of optimum (w_opt) or at optimum (w_opt), and at a selected dry unit weight related to a percentage of maximum dry unit weight (γ_d,max). The selection of molding water content (w), either wet or dry of optimum (w_opt) or at optimum (w_opt) and the dry unit weight (γ_d,max) may be based on past experience, or a range of values may be investigated to determine the necessary percent of compaction.

5.3 Experience indicates that the methods outlined in 5.2 or the construction control aspects discussed in 5.1 are extremely difficult to implement or yield erroneous results when dealing with certain soils. 5.3.1 – 5.3.3 describe typical problem soils, the problems encountered when dealing with such soils and possible solutions for these problems.

5.3.1 Oversize Fraction—Soils containing more than 30 % oversize fraction (material retained on the ³/₄-in. (19-mm) sieve) are a problem. For such soils, there is no ASTM test method to control their compaction and very few laboratories are equipped to determine the laboratory maximum unit weight (density) of such soils (USDI Bureau of Reclamation, Denver, CO and U.S. Army Corps of Engineers, Vicksburg, MS). Although Test Methods D4914/D4914M and D5030/D5030M determine the “field” dry unit weight of such soils, they are difficult and expensive to perform.

5.3.1.1 One method to design and control the compaction of such soils is to use a test fill to determine the required degree of compaction and the method to obtain that compaction, followed by use of a method specification to control the compaction. Components of a method specification typically contain the type and size of compaction equipment to be used, the lift thickness, acceptable range in molding water content, and the number of passes.

Note 3: Success in executing the compaction control of an earthwork project, especially when a method specification is used, is highly dependent upon the quality and experience of the contractor and inspector.

5.3.1.2 Another method is to apply the use of density correction factors developed by the USDI Bureau of Reclamation (2, 3) and U.S. Corps of Engineers (4). These correction factors may be applied for soils containing up to about 50 to 70 % oversize fraction. Each agency uses a different term for these density correction factors. The USDI Bureau of Reclamation uses D ratio (or D–VALUE), while the U.S. Corps of Engineers uses Density Interference Coefficient (I_c).

5.3.1.3 The use of the replacement technique (Test Method D698–78, Method D), in which the oversize fraction is replaced with a finer fraction, is inappropriate to determine the maximum dry unit weight, γ_d,max, of soils containing oversize fractions (4).

5.3.2 Degradation—Soils containing particles that degrade during compaction are a problem, especially when more degradation occurs during laboratory compaction than field compaction, as is typical. Degradation typically occurs during the compaction of a granular-residual soil or aggregate. When degradation occurs, the maximum dry-unit weight increases (1, p. 73) so that the laboratory maximum value is not representative of field conditions. Often, in these cases, the maximum dry unit weight is impossible to achieve in the field.

5.3.2.1 Again, for soils subject to degradation, the use of test fills and method specifications may help. Use of replacement techniques is not correct.

5.3.3 Gap Graded—Gap-graded soils (soils containing many large particles with limited small particles) are a problem because the compacted soil will have larger voids than usual. To handle these large voids, standard test methods (laboratory or field) typically have to be modified using engineering judgement.

Note 4: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection, and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.

Subcomité:

D18.03

Referida por:

D1079-24, D8151-19E01, C1675-22, C0361-22, B0789_B0789M-16R21, D6270-20, D7208-23, C1479_C1479M-22, D1633-17, D6836-16, D6459-19, D7351_D7351M-21, D0559_D0559M-15R23, D7243-11R20, A0807_A0807M-19, D6088-06R22, D7380_D7380M-21, D4792_D4792M-13R19, D3839-14R19, D6780_D6780M-19, D0558_D0558M-19, E3331-22A, G0162-23, D0560_D0560M-16, D2321-20, D2168-10R18, B0788_B0788M-09R20, D4829-21, E2399_E2399M-19, D7765-18A, D6460-24, B0790_B0790M-16R21, D7277-16R23, F2747-19, D5567-94R18, D7762-18E01, D1452_D1452M-24, D2937-24, C0361M-22, A1115_A1115M-24, D6243_D6243M-20, D5321_D5321M-21, D1633-17, A0798_A0798M-22, D6758-18E01, D0653-24A, D4914_D4914M-16, D1883-21, D7698-21, D8298_D8298M-23, D4253-16E01, D6938-23, E2278-13R19, D5080-20, F1668-16R22, D1883-21, D5030_D5030M-21, D4647_D4647M-13R20, F3339-20, D7263-21, D5874-24, D4914_D4914M-16, E2277-14R19, D3080_D3080M-23, F2396-11R19, D8167_D8167M-23E01, D1557-12R21, A0796_A0796M-21, D4718_D4718M-15R23, D7100-11R20, D4829-21, D5084-24, D7382-20, D7263-21, D4718_D4718M-15R23, D5084-24, E2243-13R19, D7830_D7830M-14R21E01, D5102_D5102M-24, D1557-12R21, D5030_D5030M-21, D7263-21, D8297_D8297M-23, D6938-23, D6913_D6913M-17, D6913_D6913M-17

Volúmen:

04.08

Número ICS:

93.020 (Earth works. Excavations. Foundation construction. Underground works)

Palabras clave:

compaction characteristics; density; impact compaction; laboratory tests ; moisture-density curves; proctor test; soil; soil compaction; standard effort;