| dc.description.abstract | Many concrete practices, such as measuring compressive strength of concrete using concrete
cubes, have existed since the early 1900s. However, structural members such as columns,
beams and slabs differ from concrete cubes in several ways. Due to this, researchers have taken
to investigating the effect of the differences on the compressive strength test results and it was
discovered that the differences between cubes and structural members can cause variances
between compressive strength. In order to minimise the rate of deterioration and collapse of
structures, this research aims at assessing the reliability of concrete cubes in determining the
strength of concrete structures. An observation survey was done to identify the mix ratios,
water quality, mixing method and curing method applied for the concrete members at the
various construction sites. A non-destructive rebound hammer test was conducted on concrete
cubes cast on site, as well as the structural members including columns, beams, retaining walls,
staircases, and lift wells. The crushing strength test was also performed on the concrete cubes
to determine the variance between compressive strength of cubes and structural members on
twenty-six construction sites in Uganda. The results revealed an inverse relationship between
concrete strength the reliability of the cubes. This was demonstrated by the fact that the
strongest concrete mix in the study, 1:1.5:3, had the largest variance between cube and structure
strength (23%). It was further confirmed by the observation that regardless of the mix, cubes'
reliability is lower at 28 days than at 7 days. The research further found that after
concrete strength, the quality of the water used for mixing and curing had the greatest impact
on the difference between cube and structure strength, resulting in a margin of difference of
22% 28 days after casting when pond water was used. | en_US |
