DONE BY
Banoth Narasimha-205
Banoth Snehitha-206
Nikith Reddy-207
Karthik Sai-208
Varun Sagar-209
Hardened concrete is concrete that must be
sufficiently strong to withstand the structural
and service applied loads and it must be
durable enough for the environmental risk for
which it is designed. It is the strongest and
durable construction material.
Tests on Hardened Concrete
The test conducted on hardened concrete can be
classified into two main categories:
1.Destructive Tests on Concrete
2.Non-destructive Tests on Concrete
Compressive strength test (most common) –
DT.
Modulus of Elasticity – NDT.
Split-tension test – DT.
Flexural strength test – DT.
Rebound hammer test – NDT.
Penetration resistance test – NDT.
Ultrasonic pulse velocity test – NDT.
Maturity test – NDT.
ASTM C39: Cylindrical specimen (6 in. by 12
in.) is used for this test. For normal-weight
concrete: fc' range is 21 MPa to 34 MPa (3000
psi to 5000 psi). Compressive strength
depends on specimen size, larger specimens
has greater probability for weaker elements,
reducing strength and have less variability
and better representation of actual
concrete.How does failure occur? Weakest
location of hardened concrete is the
interface between cement paste and
aggregate
ASTM C469 is used to determine the chord
modulus. 3-4 loading steps are needed in this
method. Same sample is used. This method
provides a useful relationship with strength.
The range of test result is 14 GPa - 41 GPa
(2000 ksi to 6000 ksi). Poisson's
Ratio is determined using ASTM C469. Range
is between 0.11 to 0.21, depending on
aggregate, moisture, age, and compressive
This test measures the tensile strength on
concrete (ASTM C496). Cylinder is subjected
to compressive load along vertical diameter
at a constant rate until fatigue. Failure
occurs along vertical diameter due to tension
developed in transverse direction. Split
tension is computed by T = 2p/BLD where:
T = tensile strength, MPa (psi) p= load at
failure, N (psi) L = length of specimen, mm
(in.) D = diameter of specimen, mm (in.)
Tensile strength varies from 2.5 MPa to 31
MPa (360 psi to 450 psi), about 10% of
compressive strength
This
test is used for measuring Modulus of
Rupture (MR). It is an important test for road
and airport concrete pavements. Beam
specimen of square x-section is loaded into a
3-point loading apparatus·
Itis a non-destructive test performed on
hardened concrete. A spring-loaded mass hits
the concrete's surface and scale measures
how far the mass rebounds. The higher the
rebound, the harder the concrete's surface,
and the greater the concrete's strength. Use
a calibration chart graphs supplied to related
the rebound to strength. 10 to 12 reading are
performed per specimen. The test is used to
test the uniformity of the concrete.
It is a non-destructive test. Gun-like device
shoots probes into the concrete's structure.
It is performed on each of three holes in a
special template. An average depth is then
found. Depth is inversely related to the
strength. It gives a better estimate than the
rebound hammer. Rebound hammer tests
only the surface while penetration resistance
test make measurements into the depth of
the sample
Thistest measures the velocity of an
ultrasonic wave passing through the
concrete. The length between
transducers/the travel time = average
velocity of wave propagation. It is used to
detect discontinuities, cracks and internal
deterioration in the structure of concrete.
Maturity is the degree of cement hydration
which varies with time and temperature. It is
assumed that the strength is a function of
maturity for a particular concrete mixture.
Devices are used to measure the
temperature of concrete with time.
