5.2 Curing of the specimen
Upon completion of initial curing and
within 30 min after removing the molds, store specimens in moist conditions
with free water maintained on their surfaces at all times at a temperature of
73.4 ± 3 0F. Temperature between 68 and 86 0F are
permitted for a period not to exceed 3 hrs immediately prior to test, if
moisture is maintained on the surfaces of the specimen at all times, except
when capping with sulfur.
Fresh
concrete grains strength most rapidly during the first days and weeks.
Structural design is generally based on 28 days strength and 70 percent of
which is reached at the end of the first week after placing.
5.3 Capping of cylindrical specimen
Capping is applicable to cylindrical specimens [1].
A cap shall be at least as strong as the concrete. The ends of all cylindrical
test specimens that are not plane within 0.05 mm are capped. The capped
surfaces are not departed from a plane by more than 0.05 mm and shall be nearly
at right angle to the axis of the specimens. The planeness of the cap is
required to be checked by means of a straight edge and feeler gauge. Caps are
made as this as practicable and care should be taken so that flow or fracture
does not take place, when specimen is tested. Capping can be done on completion
of casting or a few hours prior to testing to specimen.
Just prior to testing, the cylindrical specimen are
capped with a sulfur mixture consisting of 1 part of sulfur to 2 or 3 parts of
inner filler, such as fire-clay. The specimens are securely held in a special jig so
that the caps formed have a true plane surface.
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