Abstract:
Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In
Ethiopia, there is no enough knowledge by the laborers, while the site engineers ignored the correct application due to some
constraints. The agreement of acceptable vibration level in fresh concrete to which tamping time duration is optimum is an issue
to obtain the desired specific compressive strength. This research study aims to evaluate the maximum time length and
techniques used to the Vibrating or Tamping fresh concrete and its effect on the compressive strength of C-25 Concrete through
internal Rodding. Therefore, to study the effects of the period by vibrating or tamping, the needle type internal vibrator was used
to test new concrete cubes based on ACI309R-96. The quality of concrete is important to make physical tests on materials used
before any actual experiments to perform. The fresh concrete samples tested by using internal vibration methods and techniques
of compaction with different time duration of 1sec, 2sec, 3sec, 4sec, and 5sec. These tests performed by using steel rod in fresh
concrete to know the Optimum time of compaction by internal vibration on the cube test of new concrete. Laboratory
experiments had been conducted to check the methods and techniques applied to construction sites, as well as site observation on
the effects of the vibration time of fresh concrete on the compressive strength and flexural strength of C-25 Concrete with
varying vibration time duration and steel rod tamping. Based on the results of cube tests of compressive strength of Concrete
Samples have been checked at 3rd day, 7th day and the 28th day. This research study found out that the Optimum period of
compaction was 3sec to produce an acceptable right quality of the concrete mix. Likewise, the flexural strength of Concrete
Sample, when it tested in the laboratory at 7th day and 28th day, the results revealed that the flexural strength improved when
vibration time increased, but the amount of water has to be reduced to obtain the desired strength. Finally, Tamping is needed to
place fresh concrete in the mold correctly. Furthermore, new concrete produced should match the properties and avoid improper
tamping or vibration applications. This situation must not cause differences in compressive strength of concrete
