Influence of non standard test procedures for determination of compressive strength and static modulus of elasticity of Portland cement

The compressive strength is one of the basic parameters to control and characterization of cement. According to the NBR 7215 ⁽¹⁾, the standard test procedure for determination of compressive strength of cement specifies the use of sand with a specific gradation and establishes specific rules for the preparation of the standard mixture of mortar, used to manufacture the test specimens. It is known that these recommendations are not always followed when testing. In the context of the present study, we aimed to investigate the influence of some deviations from the standard procedure in the results of compressive strength and modulus of elasticity of mortar. We've tested a simplified mixing procedure and the use of average sand or with controlled gradation, taking as reference the so-called sand from Tietê. We've also used two samples of CPV-ARI cement from different manufacturers. For all combinations, tests were performed to determine the compressive strength and static modulus of elasticity of mortar at 1, 3, 7 and 28 days of age. An analysis of variance (ANOVA) was performed to assess whether the variables generated significant differences. The results show that the simplified mixing procedure didn't affect the compressive strength neither the modulus of elasticity of Portland cement. The different types of sand tested only affected the compressive strength of Portland cement.

Portland cement, mechanical properties, standard testing; non standard testing