Workability of Fresh Concrete by Slump Test
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WORKABILITY
Slump test is used to determine the workability of fresh concrete. Slump test as per IS: 1199 – 1959 is followed.The apparatus used for doing slump test are Slump cone and Tamping rod.
Procedure to determine workability of fresh concrete by slump test.
i) The internal surface of the mould is thoroughly cleaned and applied with a light coat of oil.
ii) The mould is placed on a smooth, horizontal, rigid and nonabsorbent surface.
iii) The mould is then filled in four layers with freshly mixed concrete, each approximately to one-fourth of the height of the mould.
iv) Each layer is tamped 25 times by the rounded end of the tamping rod (strokes are distributed evenly over the cross section).
v) After the top layer is rodded, the concrete is struck off the level with a trowel.
vi) The mould is removed from the concrete immediately by raising it slowly in the vertical direction.
vii) The difference in level between the height of the mould and that of the highest point of the subsided concrete is measured.
viii) This difference in height in mm is the slump of the concrete.
Reporting of Results
The slump measured should be recorded in mm of subsidence of the specimen during the test. Any slump specimen, which collapses or shears off laterally gives incorrect result and if this occurs, the test should be repeated with another sample. If, in the repeat test also, the specimen shears, the slump should be measured and the fact that the specimen sheared, should be recorded.
Typical Questions
Ques 1. What is the ideal value of slump?
Answer 1 In case of a dry sample, slump will be in the range of 25-50 mm that is 1-2 inches. But in case of a wet concrete, the slump may vary from 150-175 mm or say 6-7 inches. So the value of slump is specifically mentioned along the mix design and thus it should be checked as per your location.
Slump depends on many factors like properties of concrete ingredients – aggregates etc. Also temperature has its effect on slump value. So all these parameters should be kept in mind when deciding the ideal slump
Ques 2. How does a superplasticizer effect the slump of concrete?
Answer 2 Value of Slump can be increased by the addition of chemical admixtures like mid-range or high-range water reducing agents (super-plasticizers) without changing the water/cement ratio.
Ques 3. How much time one should take to raise the cone?
Answer 3 Once the cone is filled and topped off [ excessive concrete from top is cleared ] raise the cone within 5-10 seconds.
October 11th, 2008 at 11:42 am
how much time one should take to raise the cone.
October 16th, 2008 at 2:25 pm
what is the slump required for concreting for slab?
October 27th, 2008 at 6:19 am
how does a superplasticizer effect the slump of concrete?
November 10th, 2008 at 10:08 am
what is the time required to raise the cone in slump cone test,what are the values and limits of slump cone according to the grade and quality of concrete
November 13th, 2008 at 6:23 am
What is the ideal slump for achieving workability with out affecting the stregth?
November 23rd, 2008 at 12:10 pm
plz write what is ideal slump.
December 12th, 2008 at 8:11 pm
I think that the Ideal slump is about 60mm but that depend on the usage of the concrete for example for the narrow space reinforcement we use a high workabilty which is between 10-25mm so there is no segrecation.
January 6th, 2009 at 11:26 am
why is it that it is important to check the initial slump which is right after cone raised and then the final slump after 60 seconds? thank you.
January 31st, 2009 at 3:33 pm
how much the slump for m40 concrete ?
February 8th, 2009 at 3:26 am
i need the prosedure slump in according with standard ( ASTM )
February 14th, 2009 at 12:39 pm
What is the limit for adding water and cement, to keep W/C ratio constant, to a low slump fresh concrete to increase the slump
February 21st, 2009 at 6:43 am
Using OPC and for a grade 40 concrete, what is the workability required considering the fact that a heavily reinforced beam needs to be casted and that the concrete needs to be pumped up there?
thanks
May 30th, 2009 at 2:30 am
sorry…can ans me some question pls…cause i am a newbie of this course…
1.why is the slump test is suitable for site use??
2.what are the limitation of slump test??
May 30th, 2009 at 3:00 am
somemore question need all ur help plsss….
1.what is the main forms of slump??
2.will the addition water to a ready in-situ concrete mix gave the desired water/cement ratio??
3. what is the particle size destribution….??
kindly ans my qust plss…help me…SOS
June 3rd, 2009 at 5:34 pm
when we talk about workability test on concrete…..which of the test is prefarrable…is it the slump test, the vebe time test or the flow test
June 11th, 2009 at 8:18 pm
a)why is the slump test suitable for site use?
b)wat r the limitation of slump test?
c)sketch the 3 main form of slump test?
d)will the addition of the measure water to a ready concrete mix gave the desired water/cement ratio??
June 15th, 2009 at 6:00 pm
a)why is the slump test suitable for site use?
b)wat r the limitation of slump test?
c)sketch the 3 main form of slump test?
d)will the addition of the measure water to a ready concrete mix gave the desired water/cement ratio??/
July 3rd, 2009 at 3:02 am
but i have heard that the last layer should not be tempered only finished using trowel. because by tempering this we are compacting the concrete.(specially in low water content this is required.)
July 7th, 2009 at 4:07 am
a)why is the slump test suitable for site use?
b)wat r the limitation of slump test?
c)sketch the 3 main form of slump test?
d)will the addition of the measure water to a ready concrete mix gave the desired water/cement ratio?
July 19th, 2009 at 9:34 am
Wat is the Standard mix design for concrete M35 Grade & their properties.such as compressive strength @ 7 & 28 days, slump value also.
August 18th, 2009 at 6:16 pm
what is the relationship between slump test & structural engineer
August 31st, 2009 at 2:47 am
well if the concrete is too dry (not easy to vibrate).. add up to 19 litres OR 38 litres of water into the mixer truck (full 5 m3).
September 8th, 2009 at 7:27 am
1. when to start curing the sample?
2. what is the relationship between a slump and water cement ratio?
3. what are the ratios of materials needed to do slump test in a typical mould?
September 15th, 2009 at 9:39 am
i have to do a paper presentation about this topic can any one help me & give tips
September 29th, 2009 at 11:44 am
what are the factors influencing workability of fresh concrete?
September 30th, 2009 at 2:31 am
a)what is the equipment used in the slump test and compaction factor test?
b)what is the steps taken in preparing the test materials of slump test and compaction factor test?
c)what is the factor in determining the workability of slump test and compaction factor test?
September 30th, 2009 at 11:37 am
slump means workability but workability means ? i.e. how much time we can keep our concrete at site before using?
October 14th, 2009 at 8:40 pm
what is the best water cemment ratio for the mix ratio 1:2:4..with 3kg cemment???
November 12th, 2009 at 1:49 am
How much slump should maintain for the following grade of concrete
M15 :…….
M20 :…….
M25 :…….
M30 :…….
M35 :…….
M40 :…….
M50 :…….
November 17th, 2009 at 6:48 am
whats the ideal range for slump of 36 cubic meters of concrete of floor with thickness of slab 30cm?
November 17th, 2009 at 6:52 am
how i can design under ground septic tank (7.2m width and 10m length with 3.1m high)and furface of tank flush with surface level? please if there is any specific procedure thanks for advance
December 6th, 2009 at 8:32 am
1-what is the best slump 10-30mm or slump 30-60 for workability?and why?
2-what is the best cement for concrete?why?
3-best zone of aggregate?why?
December 18th, 2009 at 8:30 am
conclusion of workability of fresh concrete.
December 19th, 2009 at 2:01 am
why is the test done and the frequency at which is done at site
December 19th, 2009 at 2:07 am
a)why is the slump test suitable for site use?
b)wat r the limitation of slump test?
c)sketch the 3 main form of slump test?
d)will the addition of the measure water to a ready concrete mix gave the desired water/cement ratio??/
December 19th, 2009 at 3:26 am
why is the slump test done and the frequency at which it is done at site?
January 4th, 2010 at 6:05 am
How much slump should maintain for the following grade of concrete
M15 :…….
M20 :…….
M25 :…….
M30 :…….
M35 :…….
M40 :…….
M50 :…….
January 4th, 2010 at 6:07 am
what is metarial test of murrum?
January 18th, 2010 at 7:23 pm
What are relationship among+slump, compaction factor and vb test in terms of results obtained.
January 20th, 2010 at 9:50 am
The slump test is intended to get an idea of the flow behaviour, or rheology, of the mix. It is an empirical test, and doesn’t tell a lot about the state of the mix, though is useful for an indication of batch-to-batch variations. I would recommend using a purpose-designed workability test such as the CTPT” which is designed to measure the rheological behaviour of the mix. A probe of “standard” geometry is rotated in a sample of the mix at a range of controlled speeds, and the torque generated at each speed is recorded. A plot of speed vs torque gives a line characteristic of the flow properties.
Cement and Concrete mixes generally behave as “Bingham Fluids”, this is to say that they do not start to flow until a yield stress has been overcome, and then the torque is linearly related to speed; this allows the flow to be characterised by the slope of the line and the yield torque.
Work has shown that these parameters vary with water content, aggregate type and content, sand:cement ratio and so on.
Hope this helps
Roy
February 2nd, 2010 at 12:25 am
In general,at what slump value should the concrete cubes be casted at the site if it is coming from a RMC manufacturer. Any specific standards mentioned for the same. If not, if the cubes are casted at a higher slump say 150mm&above or at a relatively lower slump say 100mm&below what effectit will have on the 3,7,&28 days compressive strength of concrete of any grade.
February 12th, 2010 at 10:12 am
1. what is the importance of slump test in concrete work?
2. what is the definition of segregation and bleeding in concrete mixture?
March 6th, 2010 at 11:03 pm
What are the significances of 7 days and 28 days compressive strength??