Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

Appendix-1
1.4 Estimating Plasticity Index Using Uppal’s Syringe
For purposes of estimating the plasticity index for rural road works, the simple Uppal’s syringe
method comes in quite handy. The Uppal’s syringe is shown in the Photo above. The method is
extremely simple, briefly given as under:
“Make a paste of soil passing 425 micron IS Sieve, adding sufficient quantity of water so as to
bring it close to the plastic limit state. The paste is put in the syringe and pushed through the
holes. If the thread coming out of the holes is unbroken and shiny, the plasticity index can be
considered to be more than 10. The threads do not come out of the syringe for soils having plasticity
index less than 5. For soils with a plasticity index between 5 and 10, the texture of the threads is
not smooth”.
1.5 Tests for Presence of Deleterious Material
UPPAL’S SYRINGE
The presence of organic matter and/or harmful salts also need to be determined in areas infested
with salts like sulphates and/or organic matter. The presence of organic matter can generally be
detected by its smell and dark colour and in some cases by the presence of fibrous materials. The
organic content can be determined by burning a weighed quantity of the soil and noting the loss
on ignition. The presence of sulphates can be detected by adding a few crystals of barium chloride
to the filtrate of soil suspension in water. If a white precipitate is formed, this gives an indication
of the presence of sulphates. From the extent of milkiness of the solution, an approximate evaluation
of sulphate content can be made, with experience.
Appendix-1/2