Page 172 - Riem-Vol6_nº2

343 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 2
E. POLESELLO | A. B. ROHDEN | D. C. C. DAL MOLIN | A. B. MASUERO
After casting, TS were stored and sheltered with a plastic liner for
the first 24 hours to prevent water loss by evaporation. They were
then removed from the molds and labeled. After labeling they were
placed in a tank with saturated lime water at 23±2ºC and cured in a
controlled temperature chamber at the NORIE/UFRGS laboratory
until the test age, 28 days, was reached, as specified by Brazilian
Standard NBR 5738 (2003).
Compressive strength, the most important property of concrete,
was measured at 28 days, according to Brazilian Standard NBR
5739 (2007). A total of 15 TS were cast for each composition (three
TS for each mixing interval). The surface of the TS is ground one
day before the compressive strength test to ensure the planeness
and perpendicularity of test surfaces. Compressive strength tests
were performed in a servo controlled Shimadzu press of 2.000 kN
at a compressive speed of 0.45 MPa/s, which was kept constant
through the test.
Figure 2 – Checking the slump and restoration to the initial condition (120±20mm)
by incorporating superplasticizer to the mixture during a period of 6 hours
Figure 3 – Average results of compressive strength at 28 days of concrete produced in laboratory