Concrete quality issues in multistory building construction in Ghana: Cases from Kumasi metropolis

Evaluating the Impact of Material Selections, Mixing Techniques, and On-site Practices on Performance of Concrete Mixtures

“…Indeed, Schmidt et al [11] noted through site inspection that hand mixing is widespread on construction sites in Congo and is predominantly performed by laborers. Similarly, Tutu et al [4] reported significant instances of hand mixing at construction sites in Ghana. The preference for hand mixing is often attributed to cost-saving measures and the volume of concrete often required for such construction projects [4].…”

“…Similarly, Tutu et al [4] reported significant instances of hand mixing at construction sites in Ghana. The preference for hand mixing is often attributed to cost-saving measures and the volume of concrete often required for such construction projects [4].…”

“…The fresh and hardened properties of concrete rely on the characteristics and volume fractions of these primary components, along with the Thus, the quality of both the sand and coarse aggregate is essential in assessing the performance of structural concrete. Nevertheless, many local contractors in various parts of Africa often use readily available sand and coarse aggregate without considering their potential impact on the performance of the concrete [4,7,[9][10][11]. Moreover, many of these contractors often lack the resources or capacity to conduct quality control on these materials before their use on site.…”

“…Although the hand mixing method is commonly regarded as suitable only for non-structural works due to concerns such as slurry loss and non-uniform mixing [4,19], many local contractors employ this method for both structural and non-structural works. Indeed, some contractors argue that hand mixing of concrete at the construction site can yield quality concrete that meets structural requirements when executed properly by experienced batchers.…”

“…However, reliable material data on hand-mixed concrete (using shovels and wheelbarrows) is scarce, making it challenging to either support or challenge such claims. Despite numerous academic studies conducted in this area, most notably references [4,11,[19][20][21], most of these studies have not thoroughly investigated the impact of the hand mixing method on the quality of the concrete mixtures, especially in real-world scenarios. For instance, references [4,11] did not quantitatively evaluate the influence of the hand mixing process on the quality of the concrete batches.…”