In the comparison of Atterberg and Higidense tests the Atterberg 

 liquid limit-*- was determined by using a liquid limit device. This 

 instrument consists essentially of a b^ass cup, crank and cam mecha- 

 nism, and carriage mounted on a hard rubber base (fig. 2). A standard 

 grooving tool, made of l/l6 inch steel and having a cylindrical portion 

 on the handle end, is also an essential part of the instrument. The 

 cylindrical portion which serves to adjust the drop of the cup, has a 

 diameter of 1 cm, A sediment sample of approximately 100 grams is 

 placed in the bras 3 cup and spread to form a smooth cake about 1/2 

 inch deep in the lower half of the cup (fig. 3). The sediment is then 



Figure 3. Schematic diagram illustrating the sediment 

 arrangement in cup prior to grooving 



grooved and the instrument adjusted to permit a l«cm. drop of the cup« 

 The crank is turned, alternately lifting and allowing the cup to drop 

 at the rate of 2 drops per second. 



A "flow curve" representing the relation between the moisture 

 contents and corresponding number of shocks required to make the teo 

 sides of the sample flow together for 1/2 inch along the bottom of 

 the groove (fig* li) are plotted on semilogarithmic paper (fig. 5). 

 A minimum of three trials are performed on each sediment. The mois- 

 ture content corresponding to the intersection of the flow curve and 

 the 25- shock ordinate is taken as the liquid limit of the sediment 

 sample. 



1 A more detailed description of this test procedure can be found in 

 "Standard Specifications for Highway Materials and Methods of 

 Sampling and Testing. Part II. Methods of Sampling and Testing." 

 The American Association of State Highway Officials. 19li7. pp. 198-291 



