Soil Testing Instruments

Plastic Limit Set moisture contents at which soil has smallest plasticity is called plastic limit. For determination purpose plastic limit is defined as the water content at which a soil will just begin to crumble when rolled into a thread of 3mm dia.

Soil Moisture & Temperature Recorder Automatic soil moisture suction & Soil Temperature Reorder is a complete system for monitoring, logging and graphing 7 point Soil moisture & 1 point Soil Temperature readings. Automatically reads the sensors, 12v battery powered monitor, Battery Charging through solar panel, reading frequency from every minute to every day and adjustable to suit you, 8 sensor capacity, includes temperature probe, in-field display of current reading, download the history to a computer through packable data shuttle, monitor current values. Data is saved in Excel format and can be exported.

Shrinkage Limit Set Shrinkage Limit is the maximum water content at which a reduction in water content does not cause an appreciable reduction in volume of the soil mass. At shrinkage Limit on further reduction in water, air enters into the voids of soils and thus keeps the volume constant.

The apparatus can be used to determine shrinkage limit and to calculate other shrinkage factors like shrinkage ratio, shrinkage index and volumetric shrinkage.

Cone Penetrometer for determining the Liquid Limit of Soil. This is specially useful to obtain reliable and accurate results for those soils which have low plasticity index. The percentage moisture contents determined when a cone with half angle of 15-30 minutes under a total sliding weight of 148gm penetrates 25mm gives the liquid limit.

The High Speed Stirrer This is for mechanical analysis and also other laboratory application for stirring at Speed approximately 4000 r.p.m. under load. A dispersion cup is supported and rest on the stand of the stirrer and has a removable baffle. For operation on 230-250 volts A.C. supplied without dispersion cup or baffle.

The Liquid Limit Device Casagrande Method in mechanical form is known as liquid limit method and has been in used for soil mechanics for a number of years. The liquid limit data of soils successful to correlate mechanical properties of soil, such as compressive and lower shear strength.

Liquid limit is the water content at which soil passes from zero strength to an infinitesimal strength, hence the true value of liquid limit cannot be determined. For determination purpose liquid limit is that water content at which a part of soil is that water content at which a part of soil, cut by a grove of standard dimensions, will flow together for a distance of 1.25cm under anyplace of 25 blows in a standard liquid limit apparatus. The soil the water content has some strength which is about 0.17 N/cm.sq. (17.6gms/sq.cm.). At this water content soil just passes from liquid state to plastic state.

Grain Size Analysis (Pipette Method) This is for the determination of the sub sieve particle distribution in a soil sample by mechanical analysis. An analysis of this kind expresses quantitatively the proportions by weight of the various sizes of particles present in the soil. It is recommended as a standard procedure to use dispersion agent to avoid flocculation.

The Plummet Balance Conventionally particle size distribution analysis is carried out using pipette and hydrometer methods.

Whereas in hydrometer method it is possible to determine particle sizes in the range 75 microns, the method involves computation and it is time consuming. The pipette method can be used for determining only the percentage of specific sizes loss than 0.02, 0.006 and 0.002mm as a percentage of total soil samples.

The plummet balance method to determine sub sieve particle size for the entire range is very rapid and only manipulation of height of the balance, so that plummet sinks to the right depth is required.

The percentage of soil in suspension is directly indicated y a pointer over a graduated scale.

Marsh Cone cone is used to find out viscosity of Bentonite slurry and like material. The Marsh Cone is 6 inch in diameter at the top and 12 inch long, and tapers to join a tube 2 inch long and 3/16 inch inside dia. The capacity of the funnel is 1500cc. Time in seconds required to flow out 1000cc of slurry form cone is measured as funnel viscosity of the material.

Soil Hydrometer Used for grain size analysis of soils where more than 10% of the material will pass through 75microns I.S. sieve. Manufactured from clear transparent glass having uniform clarity thought out the upper end on which density scale is engraved. The scale range is 0.995 to 1.030 density (gms/cc) at 27 0C. Smallest division on the scale is 0.0005. Note: Hydrometers for other liquids also available.

Mud Balance designed to find out specific gravities of semi Liquid like mud and other liquid having densities in the range 0.8 to 2.5. it has a stainless steel beam calibrated in specific gravities from 0.8 to 2.5. A stainless steel cup with lid and overflow vent is fitted on one side of the beam. A counter weight with cursor slides over the graduated scale. The beam has a knife edge at centre which rests in a fulcrum fitted in the stand. Leveling screws and spirit level are fitted to the stand.

Sand Pouring Cylinder this apparatus is used for the in place determination, of the dry density of compact, fine and medium grained soils and for layers not exceeding 50 cm thickness.