University of New Mexico

Civil Engineering Department

Civil Engineering Materials Laboratory, CE 305L

TIME OF SETTING OF HYDRAULIC CEMENT BY VICAT NEEDLE

ASTM C191

Scope

This test method covers the determination of the time of setting of hydraulic cement by means of the Vicat needle.

References

ASTM C187 Normal Consistency of Hydraulic Cement

ASTM C305 Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency

Apparatus

Vicat apparatus – Consists of a frame, a movable rod weighing 300 g with a 10 mm plunger on one end and a 1 mm removable needle on the other end.

Conical Ring

Glass Plate

Balance – 0.01g resolution.

Timer – 0.5s resolution.

Materials

Hydraulic Cement ~ 650 g.

Water (23°C)

Procedure

Download Procedure for Time of Setting of Hydraulic Cement

Download Excel form for Time of Setting of Hydraulic Cement

1. Mix 650 g of cement with the required amount of clean mixing water to obtain a paste of normal consistency (C187 & C305).

   a) Place all the mixing water in the mixing bowl.

   b) Add the cement to the water and allow 30 s for the absorption of water.

   c) Start the mixer and mix at slow speed (140 rpm) for 30 s.

   d) Stop the mixer for 15 s; during this rest period scrap down into the batch any paste that may have collected on the sides of the bowl.

   e) Start the mixer at medium speed (285 rpm) and mix for 1 minute.

Note: Approximately 170 g of mixing water is a good starting point to determine the normal consistency of the cement.

2. Quickly form the cement paste prepared above into the approximate shape of a ball with gloved hands. Then toss six times through a free path of about 6 inches from one hand to the other producing a nearly spherical ball shaped mass.

3. Press the ball, resting in the palm of one hand, into the larger end of the conical ring held in the other hand, completely filling the ring with paste. Remove the excess at the larger end by a single movement of the palm of the hand. Place the ring on its larger end on the glass plate, and slice off the excess paste on the smaller end at the top of the ring by a single oblique stroke of a sharp edge trowel. Smooth the top if necessary.

4. Center the paste specimen under the 10 mm end of the Vicat apparatus. Lower the movable rod until the 10 mm end makes contact with the paste. Zero the indicator. Release the movable rod. A “normal consistency” is obtained when the penetration, below the original surface after 30 seconds, is 10 mm +/- 1 mm.

5. Repeat this process, using fresh cement, with varying percentages of water until the normal consistency is obtained.

6. Prepare a normal consistency paste, using the previously determined amount of water. Mix and place the paste specimen in the ring using the procedure outlined in Steps 1 through 3 above.

7. Place the prepared specimen in a moist closet for 30 minutes after molding without being disturbed.

8. Determine the 30 second penetration using the 1 mm needle at 30 minutes and every 15 minutes thereafter until a penetration of 25 mm or less is obtained. All post 30 minute penetrations shall not be made closer than ¼ inch to a previous penetration or closer than ¼ inch to the conical mold. Place the specimen back in the moist closet between readings. Also, clean the needle between readings to remove any paste residue. Record the penetration values and determine the time for 25 mm penetration using interpolation. This is the initial setting time.

9. Determine the final setting time as the time when the needle does not sink visibly into the paste.

Report

1) The initial setting time to the nearest 5 minutes.

2) The final setting time to the nearest 5 minutes.