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Unformatted text preview: ween the mortar and the coarse
rn genera1 the concrete shall be 14 days old before the speciaggregate.
mens are removed.
Specimens that show abnormal
defects or that have
been damaged in removal shall not be used.
B-3.1 Core Drill - A core drill shall be used for securing cylindrical
to a horizontal
a diamond drill shall he used.
B-3.2 Saw -. A saw shall be used for securing
for flcxural strength
The saw shall
have a diamond
or silicon carbide cutting
edge and shall have adjustments that will permit cutting specimens which conform to the dimensions
prescribed under B-4.2.
B-4.1 Core Specimen - A core specimen for the determination
mrnt thickness shall have a diamet-r of at least 10 cm (or 4 in ). A core
specimen for the determination
strength shall have a diameter at least three times the maximum
nominal size of the coarse aggregate used in the concrete, and in no case shall the final diameter of the
specimen be less than twice the maximum nominal size of the coarse aggre.gate.
The length of the specimen, when capped, shall be, as nearly as
twice its drameter.
39 IS : 457 - 1957
B-4.2 Beam Specimen
- A bcsm specm~cn for the determination
in general, shall iia.ve a cross-section
of 15 X 15 cm
(or 6 x 6 in ). The specimen shall be at least 53 cm ( or 21 in ) in length
but when two tests for flexural strength
are desired for one beam specimzn, it shall be at least 84 cm ( or 33 in ) in length.
NoTE - In mauy ca.&s,
the width shall be governed
hy the thickness ot the slab. B-5. particularly
with prisms cut from pavement
by the size of the coarse aggregate and the depth PROCEDURE B-5.1 Core Drilling - A core specimen taken perpendicular
to a horizontal surface shall bc located, when possible, so that its axis is pcrpendicular to the bed of the concrete as originally
A specimen taken
to a vertical surface, or perpendicular
to a surface with a
batter, shall be taken from near the middle of a unit of deposit. i.e., 380 cu m
( or 500 cu yd ) of mass concrete and from 190 cu m (or 250 cu yd) of reinforced concrete placed in any one day’s run.
B-5.2 Slab Removal - A sufficiently
large slab shall ‘be removed so
that the desired test spccimcns may be secured without the inclusion of
any concrete whicll has been cracked, spalled, undercut,
B-5 3 Beam Sawing - The sawing operation shall be so performed that
the concrete will not bc weakened by shock or by heating.
surfaces shall bc smooth, plant, parallel. and free from steps, ridges and
grow ves. Care si~all be taken in handling sawecl beam specimens to avoid
chipping or cracking.
B-6. COMPRESSIVE STRENGTH B-6.1 End Preparation--Core
to be tested in compression
shall have ends that arc essentially smooth. perpendicular
to the axis, and
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This document was uploaded on 10/01/2013.
- Fall '13