SAMPLING AND TESTING HIGHWAY MATERIALS. 
23 
reversible, and can be held in any desired position by a screw, E, and has midway 
between the ends a mark, F, which moves under a scale (graduated to millimeters) 
attached to the frame A. The paste is held in a conical, hard-rubber ring, G, 7 cm. 
in diameter at the base, 4 cm. high, resting on a glass plate, H, about 10 cm. square. 
(40) In making the determination, 500 grams of cement, with a measured quantity 
of water, shall be kneaded into a paste, as described in section 37, and quickly formed 
into a ball with the hands, completing the operation by tossing it six times from one 
hand to the other, maintained about 6 inches apart; the ball resting in the palm of 
one hand shall be pressed into the larger end of the rubber ring held in the other hand, 
completely filling the ring with paste ; the excess at the larger end shall then be re- 
moved by a single movement of the palm of the hand ; the ring shall then be placed 
C 
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Fig. 10. — Vicat apparatus. 
on its larger end on a glass plate and the excess paste at the smaller end sliced off at 
the top of the ring by a single oblique stroke of a trowel held at a slight angle with 
the top of the ring. During these operations care shall be taken not to compress the 
paste. The paste confined in the ring, resting on the plate, shall be placed under the 
rod, the larger end of which shall be brought in contact with the surface of the paste; 
the scale shall be then read, and the rod quickly released. The paste shall be of 
normal consistency when the rod settles to a point 10 mm. below the original surface 
in one-half minute after being released. The apparatus shall be free from all vibra- 
tions during the test. Trial pastes shall be made with varying percentages of water 
until the normal consistency is obtained. The amount of water required shall be 
expressed in percentage by weight of the dry cement. 
