Soil Testing Equipment

Referent and Standards Product for Soil Testing Equipment


Geotextiles are the earliest type of multifunctional geosynthetic material. Their functions include reinforcement, separation, filtration, and drainage. When impregnated, they are used as containment. However, some newly developed products perform better than geotextiles in certain functions. For example, geogrids are developed specifically to tensile reinforce soil, while geonets are used to convey large-capacity flow. Although geotextile may also be made impermeable and used as containment by spraying bitumen or other polymers on it, geomembranes should be considered for a watertight containment system. The functions of geotextiles, geogrids, and geonets are described collectively in this section, where one material can be referred to the other.
Geotextile sheets are manufactured from fibers or yarns. Polymers are melted and forced through a spinneret to form fibers and yarns. They are subsequently hardened and stretched. The manufacturing process produces
woven or nonwoven geotextiles. In producing woven fabrics, conventional textile-weaving methodologies are used. For the nonwoven fabrics, the filaments are bonded together by thermal, chemical, or mechanical means (i.e., heating,using resin, or needle-punching).
Geogrids are mainly used as tensile reinforcement. Although biaxial geogrids are available, most geogrids are manufactured to function uniaxially. In manufacturing uniaxial geogrids, circular holes are punched on the polymer sheet, which is subsequently drawn to improve the mechanical properties. For biaxial geogrids, square holes are made on the polymer sheet, which is then drawn longitudinally and transversely. For some geogrids, the junctions between the longitudinal and transverse ribs are bonded by heating or knit-stitching.
Geogrid manufactured from yarns are typically coated with a polymer, latex, or bitumen. Geogrids have higher stiffness and strength than most geotextiles. 

The chapter now describes some major applications of geotextiles and related products

Reinforcement of Steep Slopes, Retaining Structures, and Embankments

Geotextiles and geogrids are used to tensile reinforce steep slopes, retaining structures, and embankments constructed over soft foundation (Fig. 1). Sheets of geotextile/geogrid are embedded horizontally in these soil structures. The shear stress developed in the soil mass is transferred to the geotextile sheets as tensile force through friction. The tensile strength of geotextile/geogrid and its frictional resistance with the soil are the primary items required for design.

The tensile strength of geosynthetic is obtained from the wide-width test. The ASTM standard specifies an aspect ratio (width-to-length) of 2 (i.e., 20 cm to10 cm). Soil confinement may increase the stiffness and strength of nonwoven spun-bonded needle-punched geotextile because of the interactions among the fibers, but it has negligible effect on the heat-bonded nonwoven geotextiles and woven geotextiles. Reduction factors (also known as partial factors of safety) are applied considering possible strength reduction of geotextiles by installation damage, creep, chemical and biological actions. Geotextiles may degrade by exposure to ultraviolet rays, high temperature, oxidation, and hydrolysis (when the environment is highly alkaline), but the effect is minimized when buried in soils.

The frictional behavior of a geotextile with site-specific soil must be determined by direct shear tests. Although the ASTM standard specifies a direct shear box with dimensions of 30 cm by 30 cm, the box with a plane area of 10 cm by 10 cm would be adequate for geotextiles. Pullout tests have been proposed in the last few decades for determining the anchorage capacity of geosynthetics; such tests are not relevant in determining the design parameters because they are subject to scale and boundary effects. For embankments and dikes constructed over a soft foundation that lacks bearing capacity and global stability, a layer or more of geotextile is laid at the base of the embankment. Vertical wick drains of geosynthetic composites or sand drains may be used to accelerate consolidation of the soft foundation. 

Geotextiles have also been used in conjunction with the underwater sand capping of contaminated submarine sediments. In these applications, the seam strength may dominate the design.

Both geotextiles and geogrids are used to reinforce steep slopes and retaining walls. For applications where large tensile stiffness and strength of reinforcement are required, geogrids should be used. A large shear box is
required to determine the frictional properties of the geogrid because the aperture size is large relative to the geotextile. Unlike geotextiles, where frictional behavior dominates the interaction with soil, the junction of some geogrids may provide interlocking. As geotextiles are very flexible, they are typically wrapped around the face of the slope or retaining wall and protected by vegetation, gunite, timber face, or concrete panels to prevent degradation by ultraviolet rays and vandalism.
Geogrids are increasingly used with modular blocks to provide an aesthetically pleasant wall appearance. As such, the connection between the blocks and geogrids plays an important role in design. The creep and stress relaxation behavior of geogrids are also studied in conjunction with wall design. In the design of reinforced slopes and walls, a limit equilibrium approach is used. The structure is checked for internal and external stabilities. In the internal stability analysis, a failure wedge is postulated and it is tied back into the stable soil zone. An adequate strength and length of reinforcement are secured. Theexternal stability is evaluated in a manner similar to conventional gravity/cantilever wall design. In the external stability analysis, possible modes of failure, such as direct sliding, overturning, and bearing capacity, are evaluated. The seismic design of reinforced slopes and retaining walls has also received wide attention in recent years.

Filter and Drainage Layer

Geotextiles are used to replace granular soil filters in the underdrain, as well as paved and unpaved roads. They are also used as chimney drain in an earth dam and behind retaining walls (Fig. 2). The hydraulic properties are a major consideration in design. The flow rate obtained from the tests is reduced using reduction factors considering soil clogging and blinding, creep reduction of void space, intrusion of adjacent materials into geotextile voids, chemical clogging, and biological clogging.
When functioning as a filter, the geotextile sheet is required to retain the soil while possessing adequate permeability to allow cross-plane flow to occur. The permittivity or permeability and apparent opening size or equivalent opening size of the geotextile are used in design. Permittivity is the coefficient of hydraulic conductivity normalized by the thickness of the geotextile. The filter is also expected to function without clogging throughout the lifetime of the system. The gradient ratio test and long-term flow tests may be used to investigate the clogging potential.


Figure 2 Geotextile as drainage layer or filter: (a) chimney drain in earth dam; (b) drain behind retaining wall; (c) underdrain; (d) drainage layer in tunnel.

If the geotextiles (usually nonwoven needle-punched geotextiles) are used as a drainage layer, the in-plane permeability is considered. Because the thickness decreases with increasing normal stress acting on it, the term “transmissivity” is used, where the coefficient of hydraulic conductivity is normalized by the geotextile thickness

Large-Capacity Flow with Geonets/Geocomposites

For drainage applications (such as landfills and surface impoundments), geonets and geocomposites are preferable to geotextiles. These are specifically manufactured to allow for large-capacity flow. Geonets have a parallel set of ribs overlying similar sets at various angles for drainage of fluids. Most geonets are manufactured from polyethylene. They are laminated with geotextiles on one or both surfaces to form drainage geocomposites (Fig. 3). Geonets are mostly manufactured from polyethylene; thus they have high resistance to leachate.

In geonets/geocomposites, the flow is no longer laminar, and thus Darcy’s law is invalid. The flow rate is used in lieu of transmissivity or coefficient of hydraulic conductivity to account for the turbulent flow. Because of the large normal stress acting on the plane of geonet/geocomposites, the crushing strength of the core has to be assessed. Geocomposites are sometimes tested with site-specific soils and liquid. A reduction in the flow rate is expected because of the intrusion of the geotextiles into the core. It is also important to ensure that geotextile sheets, if installed along the slope, do not delaminate from the geonets due to shear stress, because geocomposites are installed at a gradient to allow for gravity flow. The drainage systems of a geocomposite are usually constructed for allowance of cleaning by flushing because they are normally subject to biological

Figure 3 Geocomposite.

Separation and Reinforcement in Roadways

In the unpaved roads and railways, geotextile separates the subgrade and stonebase/ballast (Fig. 4). The California bearing ratio (CBR) of the soil subgrade may be used to determine if an unpaved road should be designed for separation or for separation and reinforcement. The intrusion of stone aggregates into the soil
subgrade is prevented by the geotextile in a roadway. In a railway, the fine soil particles are stopped from pumping into the stone aggregates. In addition to tensile strength, other mechanical properties of geotextiles, such as resistance to burst, tear, impact, and puncture, are used for designing geotextiles as a separator.

However, existing practice does not emphasize design when geotextiles are used as a separator compared to reinforcement and drainage applications. For unpaved roadways, the use of geotextile reinforcement results in cost savings because the thickness of stone aggregates may be reduced. In paved roads, the geotextiles may prevent reflective cracking. The geotextile or biaxial geogrids may be placed above the cracked old pavement followed by the asphalt overlays. The life of the overlay is prolonged in the presence of geosynthetic
materials, or a reduced thickness of overlay may be used while keeping the lifetime equivalent to the case without using the geotextile. In addition to preventing reflective cracking, the geosynthetic reinforces the asphalt pavement.
Figure 4 Geotextile as separator in unpaved roadway.

Coastal and Environmental Protection
Geotextiles are placed under erosion control structures, such as rock ripraps and precast concrete blocks (Fig. 5a). They are also used as silt fences at construction sites so that the soil particles are arrested from the runoff water. Geotextiles are also used as geocontainers on land or underwater as storage for slurry and for coastal protection. On land, the dredged materials or sands are pumped under pressure into sewn geotextile sheets. The geotextile inflates to form a tube (Fig. 5b). Geotextile tubes are extremely effective in dewatering the high-water-content slurry/sludge by acting as a filter. The geotextile tube may also be used as an alternative to dike and coastal protection. In such applications, the strength and filter characteristics of the geotextile are important design criteria.

Geocontainers are used for the disposal of potentially hazardous dredged materials and offer a more environmental-friendly means of disposing dredged materials offshore. The geotextile sheets are laid at the bottom of dump barges, filled with dredged sediments, and sewn. The containers are then transported to
the disposal site and dumped via a split hull barge.

Civil and Environmental Applications of Geosynthetics


Geosynthetics include exclusively manmade polymeric products such as geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, and geocomposites. The term “geosynthetic” is used in favor of
geotextiles and geofabrics because 
  1. additional polymeric products are being developed and used with soils and 
  2.  the application is becoming more diversified.
Polypropylene, polyester, polyethylene, polyamide, polyvinyl choride, and polystyrene are the major polymers used to manufacture geosynthetics. It is not the properties of the polymers, but the properties of the final polymeric products that are of interest to civil and environmental engineering applications. Geosynthetics are used as part of the geotechnical, transportation, and environmental facilities. Geosynthetic products perform
five main functions: separation, reinforcement, filtration, drainage, and containment (hydraulic barrier). However, in most applications, geosynthetics typically perform more than one major function.


A. Testing Standards
Some basic standards used for geotextiles are adopted from the textile industries. However, geotechnical engineers realized the deficiencies and started to develop the standards relevant to their applications. The American Society for Testing and Materials (ASTM) is one developer of standardized testing procedures for
different geosynthetics. Most testing standards adopted or developed in other countries are outgrowths of ASTM standards. The Geosynthetic Research Institute (GRI) also provides testing standards to serve industrial needs, especially when related ASTM standards have not been developed. GRI standards are usually removed as related ASTM standards become available. ASTM standards, developed under Committee D35 for Geosynthetics, are listed in the Appendix. These standards were developed under several
subcommittees: terminology, mechanical properties, endurance properties, permeability and filtration, geosynthetic clay liners, geosynthetic erosion control, and geomembranes. New standards are constantly being developed. Details of test standards are published in ASTM (2000).
While ASTM standards are index tests, many civil engineering designs and applications require the geosynthetic materials to be tested with site-specific soils, with the testing conditions representing those in the field. These kinds of tests are known as performance tests.

B. Design by Function

Different organizations, agencies, and manufacturers provide design guidelines for geosynthetic applications. These design methods are determined by cost, specification (design by specification), or function (design by function). Public agencies have widely adopted the design-by-specification method. The minimum required value of the geosynthetic properties used in a particular application is specified. In the design-by-function method, the primary function of the geosynthetic material is identified. The available and required value of the particular property for that function is assessed to give a factor of safety (FS):

FS = allowable property from testing / required property for design

Designs require a factor of safety greater than unity to account for various uncertainties.

source : Marcel Dekker Inc (Reinforced  Soil Engineering)

Standard Test Procedures Manual - Stratigraphic Holes

Standard Test Prosedures Manual
Section :   SOILS

  1. Description of Test : This method covers the sampling of soils from stratigraphic holes. 


  1. A suitable drilling rig equipped with a 150 mm auger.
  2. Suitable bags and sampling containers such as tares to retain the natural moisture
  3. Munsel color chart.
  4. Pocket penetrometer


  1. Sampling :  Drill stratigraphic holes averaging 1.5 km intervals or less depending upon terrainevaluation,  along either hubline.  The depth of these holes will be pre-determined by the District Materials Engineer or designate, usually a 13.5 m depth is adequate. Record the hole number, station, offset from centerline as shown in Figure 104-1. Drill continuously until each sample depth is reached then pull the auger up rather than twist it to obtain a good sample.  Depths usually tested for moisture content are 0.3, 0.9,1.5m and then every 1.5 m until total depth is reached.Color coding and penetrometer readings may be taken when sampling for moisturecontent.  Moisture contents are required for topsoil and sand but no gravel.  Use STP 205-3 for moisture contents. Record the above information on Figure 104-1 together with any other pertinent remarks such as depth to water table, and depths at which rocks were encountered in the hole. Also include iron staining, odor from organic material, fossils, etc.The technician will inspect every 0.3 m of material to determine any soil changes.  If any change occurs, the depth will be recorded.  The Drill Operator can usually detect material changes by noting any changes in the rotational pressure gauge.
  2. Bagging and Labeling : lace a 3-5 kg sample of each soil type in a paper bag for further testing.  Control section, hole number, station, depth and type of material must be written on the bag and written on tag and placed in the bag. If granular material is encountered, take a 4000 g sample every 1.5 m in depth.

  1. Reporting Results : Complete as shown in Figure 104-1.


  1. Additional Testing : This information is required to determine if further testing should be completed.  All sample and any material changes should be clearly defined and well documented.
  2. Geological Soil Symbols : Symbols used for geological soil classification are as follows:
    TS  - Sutherland Till
    TB - Battleford Till
    TF - Floral Till
       u - Subscript to describe an unoxidized till eg: TFu
       o - Subscript to describe an oxidized till eg: TFo
      Sl - Silt
    CL  - Clay
    SD  - Sand
    GR - Gravel

FIGURE 104-1

source :

Standard Test Prosedures Manual - Fine and Coarse Aggregate Test Set

Standard Test Prosedures Manual
Section :   SAMPLING

  1. Description of Test : This method covers the sampling of coarse and fine aggregates for further testing as requiredaybolt viscosity is expressed in units of furol seconds at a specified temperature.

  1. Sampling pan. 
  2. Sample scoop. 
  3. Sample splitter and receptacles.  
  4. Sample bags or containers. 
  5. Sample identification tags. 
Number and Masses of Field Samples  

The required sample size is based on the type and number of tests to which the material is to be subjected. Amounts specified in Table No. 1 will provide adequate material for routine testing and quality analysis. For routine control, take one sample for every 2 hours of plant production. 


Samples will be reduced at the laboratory to testing size with the use of a sample splitter or by the quartering method. 

Shipping Samples
Transport aggregates in bags or containers that are constructed to prevent loss or contamination of any part of the sample, or damage to the contents from mishandling during shipment. Enclose complete identification with the sample to facilitate reporting of test results. 


  1. Sampling from the Conveyor Belt. Obtain at least three approximately equal increments selected at random from the unit or ot being sampled and combine to form a field sample whose mass equals or exceeds the minimum recommended in Table No. 1. Stop the conveyor belt while the sample increments are being obtained. Select a representative section in the middle of the belt.  Remove enough material from within the selected section such that the material contained will yield the required
    weight.  Carefully place all material into a container.    
  2. Sampling from a Flowing Aggregate Stream (Bins or Belt Discharge). Select samples by random method from the production. Sample from belt discharge only when plant is operating at normal capacity. Sample from bin discharge only when bins are nearly full in order to minimize change of obtaining segregated material. Obtain at least three approximately equal increments, at random and combine to form a field sample whose mass equals or exceeds the minimum recommended in Table No. 1. Take each increment from the entire cross section of the material as it is being discharged. For larger plants, a special sampling device may have to be constructed on site in order to accomplish the above requirement.  A rail or pivot system should be constructed to convey a sampling pan through the discharge stream at a uniform rate.  The pan must be large enough to intercept the entire flow and hold the required amount of sample without over flowing.
  3. Sampling In Place On Road (Bases and Subbases) . Select sample blocks or areas from completed construction work representing 500 t of production, or in accordance with respective contact specifications. Use a random method to select a representative sample from at least 3 sites within the area to be tested.  Combine all 3 samples to form a single field sample that can be reduced as required to the specified size in accordance with the respective contract specifications and test procedures. Clearly mark the specific areas from which the increment is removed.  A metal template placed over the area is a definite aid in securing approximately equal increment weights.Take all samples from the roadway for the full depth of the material, taking care to exclude any underlying material.
  4. Sampling From Windrow . Select sample blocks or areas from completed construction work representing 500 t of production, or in accordance with respective contract specification. Use a random method to select a representative sample from at least 3 sites within the areas to be tested.  Combine all 3 samples to form a single field sample that can be reduced as required to the specified size in accordance with the respective contract specifications and test procedures.

Aggregate samples may be taken for one of several reasons such as preliminary investigation of the source of supply, to control the product at the source of supply or to control operations at the site and to accept or reject material.

Sampling is equally as important as the testing and the sampler must use every precaution to obtain samples which will show the true nature and condition of the materials which they represent.  Sampling from the initial or final material discharge from a conveyor belt or a bin increases the chances of segregation and should be avoided.  The samples are to be taken while the plant is in full operation.

Samples for preliminary investigation testing are obtained by the party responsible for the development of the potential source (e.g. Gravel Investigation). Where practical, samples to be tested for quality should be obtained from the finished product.

source :

Standard Test Prosedures Manual - Marshal Stability and Flow - Asphalt Mixes

Standard Test Prosedures Manual


  1. Description of Test This method covers the measurement of resistance to plastic flow of cylindrical specimens of asphalt mixtures loaded on the lateral surface by means of the Marshall apparatus.  This method is for use with mixtures containing asphalt cement, asphalt cutback, and aggregate up to 25.4 mm maximum size. 
  2. Application of Test. The testing section of this method can also be used to obtain maximum load and flow for asphalt concrete specimens cored from pavements or prepared by STP 204-8, Preparation of Marshall Compaction Specimens.
  3. Units of Measure .Stability is measured in Newtons.  Flow is measured in mm

Equipment Required
  1. Breaking Head - the breaking head shall consist of upper and lower cylindrical segments or test heads having an inside radius of curvature of 50.8 mm accurately machined.  The lower segment shall be mounted on a base having two perpendicular guide rods or posts extending upward.  Guide sleeves in the upper segment shall be in such a position as to direct the two segments together without appreciable binding or lose motion on the guide rods.
  2. Loading Jack - the loading jack shall consist of a screw jack mounted in a testing frame and shall produce a uniform vertical movement of 50.8 mm/minute.  An electric motor may be attached to the jacking mechanism.
  3. Ring Dynamometer Assembly or Electronic Equivalent - one ring dynamometer of 2267 kg capacity and sensitivity of 4.536 kg up to 453.6 kg and 11.34 kg between 453.6 and 2267 kg shall be equipped with a micrometer dial.  The micrometer dial shall be graduated in 0.0025 mm.  Upper and lower ring dynamometer attachments are required for fastening the ring dynamometer to the testing frame and transmitting the load to the breaking head.
  4. Flowmeter - the flowmeter shall consist of a guide sleeve and a gauge.  The activating pin of the gauge shall slide inside the guide sleeve with a slight amount of frictional resistance.  The guide sleeve shall slide freely over the guide rod of the breaking head. The flowmeter gauge shall be adjusted to zero when placed in position on the breaking head when each individual test specimen is inserted between the breaking head segments.
  5. Water Bath - the water bath shall be at least 152 mm deep and shall be thermostatically controlled so as to maintain the bath at 60 ± 1o C.  The tank shall have a perforated false bottom or be equipped with a shelf for supporting specimens 51 mm above the bottom of the bath.
  6. Air Bath - the air bath for asphalt cutback mixtures shall be thermostatically controlled and shall maintain the air temperature at 25 ± 1o C
Materials Required
  1. Samples may include cored specimens, field or lab prepared specimens
Sample to be Tested
  1. Density of the specimen is required to obtain the volume for a correlation ratio.  Density can be determined as outlined in STP 204-21, DENSITY AND VOID CHARACTERISTICS.

Equipment Preparation
Thoroughly clean the guide rods and the inside surfaces of the test heads prior to making the test, and lubricate the guide rods so that the upper test head slides freely over them.

Sample Preparation
Samples will be prepared in accordance with STP 204-8, Preparation of Marshall Compaction Specimens or collected in accordance with STP 204-5, Asphalt Concrete Samples Obtained by Coring.

Test Procedure

Bring the specimens prepared with asphalt cement to the specified temperature by immersing in a water bath 30 minutes.  Maintain the bath or oven temperature at 60 ± 1o C for asphalt cement specimens.  Bring the specimens prepared with asphalt cutback to the specified temperature by placing them in the air bath for a minimum of 2 hours. Maintain the air bath temperature at 25 ± 1o C. The testing head temperature shall be maintained between 20 to 38o C.  Remove the specimen from the water bath, oven or air bath and place in the lower segment at the breaking head.  Place the upper segment of the breaking head on the specimen and place the complete assembly in position on the testing machine.  Place the flowmeter, where used, in position over one of the guide rods and adjust the flowmeter to zero while holding the sleeve firmly against the upper segment of the breaking head.  

Hold the flowmeter sleeve firmly against the upper segment of the breaking head while the test load is being applied.  Apply the load to the specimen by means of the constant rate of movement of the load jack or testing machine head of 50.8 mm/minute until the maximum load is reached and the load decreases as indicated by the dial.  Record the maximum load noted on the testing machine or converted from the maximum micrometer dial reading.  Release the flowmeter sleeve or note the micrometer dial reading, where used, the instant the maximum load begins to decrease.  Note and record the indicated flow value or equivalent units in mm if a micrometer dial is used to measure the flow. The elapsed time for the test from removal of the test specimen from the water bath to the maximum load determinations shall not exceed 30 seconds.


Collection of Test Results
For specimens other than 63.5 mm in thickness correct the load by using the proper multiplying factor from Table 1. The reports shall include the following information:
  1. Type of sample tested (lab sample or pavement core specimen).  For core specimens the height of each test specimen in mm shall be reported.
  2. Average maximum load in newtons, corrected when required.
  3. Average flow value in millimetres.
  4. Test temperature
TABLE 1 - Stability Correlation Ratios*
Volume of Specimen       Thickness of Specimen      Correlation Ratio
             (cm3)                                (mm)
200 to 213                                     25.4                         5.56
214 to 225                                     27.0                         5.00
225 to 237                                     28.6                         4.55
238 to 250                                     30.2                         4.17
251 to 264                                     31.8                         3.85
265 to 276                                     33.3                         3.57
277 to 289                                     34.9                         3.33
290 to 301                                     36.5                         3.03
302 to 316                                     38.1                         2.78
317 to 328                                     39.7                         2.50
329 to 340                                     41.3                         2.27
341 to 353                                     42.9                         2.08
354 to 367                                     44.4                         1.92
368 to 379                                     46.0                         1.79
380 to 392                                     47.6                         1.67
393 to 405                                     49.2                         1.56
406 to 420                                     50.8                         1.47
421 to 431                                     52.4                         1.39
432 to 443                                     54.0                         1.32
444 to 456                                     55.6                         1.25
457 to 470                                     57.2                         1.19
471 to 482                                     58.7                         1.14
483 to 495                                     60.3                         1.09
496 to 508                                     61.9                         1.04
509 to 522                                     63.5                         1.00
523 to 535                                     64.0                         0.96
536 to 546                                     65.1                         0.93
547 to 559                                     66.7                         0.89
560 to 573                                     68.3                         0.86
574 to 585                                     71.4                         0.83
586 to 598                                     73.0                         0.81
599 to 610                                     74.6                         0.78
611 to 625                                     76.2                         0.76

The measured stability of a specimen multiplied by the ratio for the thickness of the specimen equals the corrected stability for a 63.5 mm specimen.