To
Determine The Compressive Strength of Concrete Cubes And Cylinders.
1.
Empty/ Material
Cylinders/
cubes molds, Weighing ,Balance, Cone mixer machine, mixing trays, floats,
trowels, compression testing machine, vibrating table and cone making materials.
2.
Procedure
a.
Take
the ingredient of concrete i.e. C Aggregate, F Aggregate and cement plus
required W/ element ratio. Mix them in
concrete mixer for about 3 Minutes.
b.
Place the cylinders/cubes on vibrating table
and fill them in three layers, cache layer should be compacted properly.
c.
Place
the molds in the room at a temp of 23+1.7o c for setting for setting for about
24 hours. Cover the molds with impervious.
d.
After
24 hrs remove the specimens from the molds and place them in curing tank.
e.
After
7,14 and 28 days take out the specimens from the currying tank at and cape the cylinders with capping material.
f.
Place
the cylinders/ cubes in compression testing machine in saturated surface- dry
condition.
g.
Apply
the load continuously and without shock at a constant rate of 20-50 psi/ sec
until the specimen fails, and record the maximum load carried by the specimen
during the lest . in observations note the identification mark data of casting
and testing and the area of specimen.
3.
Reactions
Ensure
the volume calculated for pouring/ casting the molds is sufficient.
Materials
should be weighed accurately.
During
hand compaction, blows should be evenly distributed and for each upper layer
allow the road to penetrate about ½ into the under layer. When depth of layer
is less then 4 and about I’’ when depth is 4’’ or more.
During
the first 24 her mold should be cover with impervious plastics sheets.
Excess
vibration should be avoided when compaction is done by vibration to avoid
segregation/ bleeding.
Cylinders
and cubes specimens should be tested in saturated surface dry condition.
At
least three specimens should be tested for each test and mean should be taken.
If individual variation is more than 15% then test result should be rejected
and test should be repeated.
Capping
of the cylinders should be dons using capping materials.
Cylinders
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S.No
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Ref/Mark
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Area
|
Load (KN)
|
Omp. Str (Psi)
|
Mean str
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1
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2
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3
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4
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5
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6
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7
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