Influence of different compacting methods on concrete compressive strength

Abstract

Adequate compacting is an important stage contributing for the durability and final quality of concrete structures.
The two main ways of compacting concrete are: manual and mechanical (immersion vibrator). This
paper has the goal of verifying the influence of those two compacting methods on the compressive strength
of concrete from long term data. In order to do that, cylindrical test specimens of a same concrete were molded
with different compacting methods and the compressive strength was investigated at 1, 3 , 7, 14, 21, 28,
63, 91, 180, 365 and 730 days. Concrete used was casted in plant. Manual compacting was performed using a
metallic and cylindrical rod. Mechanical compacting was performed using a rigid immersion vibrator driven
by an electric motor. This study confirmed greater compressive strength in test specimens compacted with
immersion vibrator, when compared with results in manually compacted test specimens. However, the novelty
of this article is that variance analysis test demonstrated that only from 63 days the difference between
compressive strengths is significant. Long term data also made it possible to generate a trend equation with
good coefficient of determination for estimating the difference between compressive strengths for the two
compacting methods investigated over time.
Keywords: Concrete, materials technology, compressive strength, durability, long term data.