The flow table test of cement mortar is used only to test the strength of masonry cement and to calculate the amount of water required for gauging for drying shrinkage test of cement. It also gives us some idea on the practicality of cement mortar.
the amount of water used to measure in terms of Compressive strength test of masonry cement, such that to produce a flow 11015s. ± 5% with 25 drops in,
the amount of water used to measure in terms of Drying Shrinkage Test of Hydraulic Cement, such that to produce a flow 110 15s. Up to 115% with 25 drops in,
To make a mortar, a specified amount of cement standard sand and water is mixed and allowed to flow by falling from a specified height over time.
|balance||1000 grams||1 gram|
|Temporary||27 ± 20 C|
|Humidity (relative)||65 ± 5%|
- Take 420 g of cement and 1440 g of standard sand and the test percentage of water.
- Mix all the ingredients mechanically with the help of a mixer.
- Pour all the mixing water into the bowl.
- Add the masonry cement to the water, then turn on the mixer and mix for 30 seconds at a slow speed (140 ± 5 rev/min).
- Slowly add the full amount of sand over a period of 30 seconds, shaking at a slow speed.
- Stop the mixer, change to medium speed (280 ± 10 rev/min), and mix for 30 s.
- Turn off the mixer and let the mortar stand for one and a half minutes. During the first 15 seconds of this interval, quickly scrape off any mortar in the batch that has collected on the side of the bowl, then for the remainder of this interval, cover the bowl with a lid.
- Finish by mixing on medium speed for one minute. If further remixing is required, any mortar adhering to the edge of the bowl will be quickly scraped down with the scraper in the batch prior to remixing which is to be continued until a uniform mortar is obtained.
- When mixing is complete, shake the paddle to remove excess mortar in the mixing bowl.
- Carefully clean and dry the Flow table top and place the mold in the middle.
- Place a layer of mortar (mixed as above) about 25 mm thick in the mold and tamp it 20 times with a tamping rod.
- Then fill the mold with mortar and tamp as specified for the first layer.
- Cut off excess mortar by pulling the straight edge of a trowel with a cutting motion across the top of the mold.
- One minute after the mixing operation is complete, lift the mold away from the mortar.
- Immediately drop the table from a height of 12.5mm, 25 bar in 15s.
Flow is the resulting increase in the average base diameter of the mortar mass, expressed as a percentage of the original base diameter, measured over at least four diameters at approximately equal-day intervals.
flow = [(Davg – Do) / Do]*100
DAverage,average base diameter
- The material will be mixed separately to mold each batch of test sample.
- The tamping pressure should be sufficient to ensure uniform filling in the mould.
IS:4031 (Part-7):1988 – Physical test methods for hydraulic cement (determination of compressive strength of masonry cement)