Electromechanical Field Density Gauge for Evaluation of Dry Density of the Compacted Fill

IPR Status (Patent/Copyright/Trademark Secured in India/Abroad)
Electromechanical Field Density Gauge for Evaluation of Dry Density of the Compacted FillA patent has been filed at CSIR
Patent Ref. No. 0063NF2014 Dated, 17TH June 2014.

The developed equipment can be wide usage for quality control of soil fills in different areas viz. Roads, Dams, Railways and other applications.  Core cutter and sand replacement methods are generally used as conventional methods to measure the field dry density of compacted soil. These conventional methods are time consuming, manual and laborious. These methods also create week spots in the compacted fill affecting the durability of roads. But with the help of developed equipment the field dry density shall be estimated without destructing the compacted soil and this method is faster than the conventional method.

Salient Technical Features including Competing Features
A non-nuclear, non-destructive, portable equipment has been designed and fabricated for measurement of dry density of compacted soils. The fabrication of the equipment involves the design/assembly of different parts. Penetration probe with cone is an important part of the equipment whose specifications have been designed considering the maximum resistance of compacted soil. A system has been designed where in the penetration probe with load cell moves in linear direction along the lead screw with the help of chain and sprocket system for measurement of penetration resistance of compacted soil. A Proximity sensor is provided to measure the linear displacement of the probe and Limit switches are provided for auto stop/cut off the electric motor after required displacement of the penetration probe. A digital display unit is attached for the measurement of maximum penetration resistance of compacted soil and linear movement of penetration probe. Different parts have been assembled and fabricated to develop the Electro-mechanical soil density gauge.

Level/Scale of Development
The first model equipment with calibration chart has been developed for local (Delhi) soil. More experiments would be carried out to develop a calibration chart between peak failure load and dry density of compacted soil samples. After, confirming about the calibration the equipment will be re-designed to make it much compact, portable and cost effective.

Environmental Considerations
The developed equipment is cost effective, non destructive, fast, reliable, portable, non nuclear. As the equipment is non nuclear, the equipment does not need license certificates from BAARC, and thus avoids health hazard.

Status of Commercialization
The developed equipment has a potential to be marketed in different civil engineering construction works specially roads, dams and railways. The technology transfer is being processed for the development of cost effective equipment for commercialization.

Major Raw Materials to be Utilized
Mild steel, Electric motor with chain and sprocket system, Electronic sensors and  digital display unit.

Major Plant Equipment and Machinery Required
Lathe machine, Surface grinding machine, Electroplating machine.

The developed equipment is cost effective, non destructive, fast, reliable and portable. The equipment is Indigenously developed and is much cheaper and cost about 25% of imported similar type of equipments.

Technology Package
The present invention relates to a method and apparatus for measuring in-place soil density and moisture content. Fabrication and development of electromechanical field density gauge was carried out after detailed laboratory testing and measurement penetration resistance of compacted silty soil (local soil) at varying densities in CBR mould. Final design of penetration probe was which is the most important part of the equipment carried out after three trials and each time design was modified corresponding the short comings. Total weight of the equipment is 60 kg, and is portable. The investigation includes the design of lead screw, support bar, cross head and chain support system for movement of penetration probe in upward / downward directions. Proximity sensor measures the linear movement of the penetration probe in the compacted soil which is shown as a digital display which stops the peak loan, N and corresponding penetration in mm. Data logger was attached which stores readings of the maximum load in N and its corresponding penetration in mm. Calibration chart is developed in between penetration resistance and degree of compaction. The fabrication also includes the design of other parts such as probe holder, brass bush and fixtures with complete assembly of electromechanical density gauge. Preliminary calibration charts where also developed between penetration resistance and dry density.