# Meta-Analysis of the Performance of Previous Concrete with Cement and Aggregate Replacements
## 5 Results and Discussion
### Cement Replacement in Pervious Concrete
#### 5.2.2 Performance Evaluation
This inferior performance may be due to the cohesive nature of OPC particles compared to those of industrial wastes and replacement materials [48]. However, very limited studies have investigated this property. In conclusion, FA, SF, BC, STF, WPF, and SCBA produced PC with improved mechanical properties. The hydraulic performance was enhanced upon replacing cement with POFA, RF, CR, SG, PU, and SCBA. However, inferior durability  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref. **} & \multirow{2}{*}{**Type**} & \multirow{2}{*}{**Percentage**} & \multicolumn{4}{c}{**Mechanical Properties**} & \multicolumn{4}{c}{**Hydraulic Properties**} & \multicolumn{2}{c}{**Durability**} \\  & & & & **Replacement** & & **Bulk** & **Compressive** & **Tensile** & **Strength** & **Flexural** & **Porosity** & **Permeability** & **Abrasion** \\  & & & & **Density** & **Strength** & **Strength** & **Strength** & **Strength** & **Porosity** & **Permeability** & **Abrasion** \\ \hline
[18] & SF & \( \begin{array}{c}5,10,15,20,\\ 25\%\end{array} \) & \(-1.6\) & \(-1.6\) & \(-0.9\) & - & \(1.8\) & - & - \\ \hline
[20] & PR & \(0.05\), \(0.1\%\) & - & \(-1.1\) & \(-1.7\) & \(-1.1\) & \(-2.1\) & \(1.0\) & - \\ \hline
[21] & SF+MK+LX & \(5\%+5\%+5\%\) & - & \(1.4\) & \(0.4\) & \(2.0\) & - & \(-2.2\) & - \\ \hline
[25] & RHA+CCW & \(5,10,15\%\) & \(20\%\) & - & \(0.0\) & - & - & - & \(-0.8\) & \(-0.6\) \\ \hline
[27] & FA & \(15\%\) & \(0.8\) & \(1.3\) & - & - & -0.8 & - & - \\  & FA+MK & \(15\%+2\%\) & \(0.3\) & \(0.9\) & - & - & \(0.5\) & - & - \\ \hline
[28] & SG & \(100\%\) & - & \(-0.5\) & - & - & \(1.4\) & \(0.2\) & - \\  & SG+RM & \(100\%+5\%\) & \(0.5\) & \(1.0\) & \(0.9\) & \(0.9\) & \(-0.6\) & \(0.6\) & \(-0.9\) \\  & SG+RM & \(100\%+5\) & \(1.8\) & \(0.8\) & \(1.1\) & \(1.1\) & \(-0.8\) & \(-1.0\) & \(-0.8\) \\ \hline
[31] & SG & \(100\%\) & - & \(-0.2\) & - & - & \(0.5\) & \(1.2\) & - \\ \hline  & PU + 2\% STF & \(10,25\), \(50\%\) & \(1.5\) & \(0.4\) & \(0.3\) & - & \(2.8\) & \(5.7\) & - \\  & PU + 2\% MF & \(10,25\), \(50\%\) & \(17.4\) & \(5.8\) & \(0.3\) & - & \(5.9\) & \(8.7\) & - \\  & PU + 2\% WPF & \(10,25\), \(50\%\) & \(-1.4\) & \(-0.5\) & \(-2.1\) & - & \(2.8\) & \(4.2\) & - \\  & PU & \(10,25\), \(50\%\) & \(0.2\) & \(0.5\) & \(-0.1\) & - & \(-0.4\) & \(24.8 performance was recorded for PC with cement replacement even though the mechanical properties had improved. Thus, there is a need for more studies to improve the durability properties of PC. The results of Table 1 are further analyzed with fixed pooled \(d\) values, as shown in Figure 4. With reference to the vertical zero dashed line, a positive pooled \(d\) value (solid black box) signifies better performance for mixes with cement replacement and vice versa. Overall, it can be observed that the mechanical performance improved with cement replacement. Despite the significant variations in the strength results, with the fixed pooled \(d\) ranging from \(-6\) to \(+2\), all fixed pooled \(d\) values for strength were positive, confirming that the mechanical properties generally improved upon cement replacement. Meanwhile, the hydraulic performance was not as significantly affected. The pooled \(d\) values fell approximately at the vertical reference line, signifying that cement replacement had a limited impact on the hydraulic properties. Conversely, the durability properties, i.e., abrasion resistance, had a negative pooled \(d\) value of nearly \(-0.6\) (range \(-11.5\) to \(-0.2\)), indicating an inferior performance of mixes with cement replacement compared to those made with cement only. This can be attributed to the limited analyzed data obtained from the six durability studies identified in Figure 2. Unexpectedly, while the strengths of these PC mixes increased upon cement replacement, the abrasion resistance decreased, possibly due to the less cohesive nature of such industrial waste particles as compared to that of the OPC [49].