The test consists to determine the setting time of cementitious mortars using the Vicat needle, an instrument that allows the subsequent penetration of a needle into the hydrated sample. According to the needle is able to penetrate the mortar, it defines the start or end setting.
The automatic Vicat needle consists of a fixed and a movable structure, the fixed structure is constituted by the truncated conical shape that contains the sample to be tested, the movable part is constituted by a slidable rod that has in the lower end a cylindrical steel needle of 1 mm2. The movable part total weight is 300 g. In addition, this instruemnt is equipped with an internal memory that allows you to make a complete work cycle programming the needle penetration ranges.
To perform the test it is necessary to place the mixture of the mortar within a truncated conical cylinder of plastic material, resting on a glass plate. The truncated conical cylinder has an upper diameter of (70 ± 5) mm, the lower of (80 ± 5) mm and has a height of (40 ± 0.2) mm. The glass sheet has a thickness upper to 2.5mm.
Once the sample is placed inside the instrument, the needle touches the top surface of the mixture and it falls so to allow the needle to penetrate in the center of the mixture. For each penetration realized it reads on the graduated rod the needle depth of penetration. The automatic Vicat needle instrument returns directly the needle penetrations measures.
The instrument records as the start setting the moment in which the needle stops to 3 mm away from the glass plate, the end setting when the needle does not penetrate more than 0.5 mm in the mixture. The test is performed in an environment maintained at temperature of 20 ± 2°C and relative humidity not less than 75%.
Recorded the value of the start and end setting, the instrument stops working cycle automatically and it returns all the readings taken, and so all penetration depth of the needle during the test with an accuracy of a millimeter decimetre.

 

Material type Standard Test method
finishing plasters EN 998-1
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screeds EN 13813
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self-levelings EN 13813
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restoring mortars EN 1504-3
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grouting mortars EN 13888
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surface protection mortars EN 1504-2
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cements EN 197-1
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Instruments used to perform the test: Vicat needle

 

It is determined through subsequent penetration of a needle into the hydrated sample.It is determined through subsequent penetration of a needle into the hydrated sample.

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