A Critical Evaluation of the Gradient Ratio Test
Tests performed in a permeameter have been used to evaluate the gradient ratio test method. The evaluation is based on observed variations of water head and permeability in the composite soil and geotextile specimen with respect to time and with imposed hydraulic gradient. A water pluviation technique was used to reconstitute homogeneous, saturated sand specimens in the permeameter at any targeted density. An energy dissipator was used to prevent disturbance of the top of the specimen by inlet water at large flow rates. Some physical clogging of the soil may result from a blinding action due to fines in the recirculating water. Biological clogging may also occur, but is eliminated by treatment of the water with an algicide.