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.
Ques 4. What are the dimensions of the cone used in Slump Test?
Answer 3 The dimensions are
Top Diameter – 10cm
Bottom Diameter – 20cm
Height – 30cm
If you have a query, you can ask a question here.
how much time one should take to raise the cone.
It should be imminently after proper filling of slump cone, or upto 10 second.
what is the slump required for concreting for slab?
how does a superplasticizer effect the slump of concrete?
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
What is the ideal slump for achieving workability with out affecting the stregth?
plz write what is ideal slump.
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.
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.
how much the slump for m40 concrete ?
i need the prosedure slump in according with standard ( ASTM )
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
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
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??
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
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
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??
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??/
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.)
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?
Wat is the Standard mix design for concrete M35 Grade & their properties.such as compressive strength @ 7 & 28 days, slump value also.