## 6 Conclusions  
The current research investigates the application of olive waste ash (OWA), produced from burning pomace--a byproduct generated during olive oil extraction--as a partial cement substitute in pavement systems. For this issue, physical properties such as density, total water absorption (TWA), and capillary water absorption (CWA) coefficient, along with mechanical properties such as the compressive strength and flexural strength of the cement paste, are evaluated. In light of the findings, the following conclusions can be made:  
* The inclusion of OWA slightly reduces the compressive strength, with optimal performance at 10% OWA, exhibiting only an 8% decrease compared to the control mixture. This suggests that paving blocks made with 10% OWA can perform well in infrastructure practices, including pedestrian sidewalks and low-traffic volume paved surfaces, attributed to their sufficient compressive strength. * The density of all specimens marginally drops with increasing OWA content, achieving a reduction of about 2.5% at 20% OWA relative to the reference paste. This results in lighter paving blocks, which are more efficient in terms of transportation and handling. * The addition of OWA results in a decrease in flexural strength regardless of the amount induced. However, the incorporation of 10% OWA leads to a flexural strength magnitude comparable to the control mixture, with only a 3% reduction, rendering it a perfect choice for sidewalks and pedestrian areas. * After 28 days of curing, OWA significantly increases water absorption, with the lowest growth observed at 10% OWA. This increase highlights the appropriateness of OWA-based paving blocks for use in permeable pavement systems, water pooling, and rain gardens. * Both hyperbolic and capillary-diffusive models accurately validate compressive strength and water absorption characteristics, reinforcing their utility in optimizing the material properties of paving blocks. * There are strong correlations between compressive strength, density, and flexural strength, while a negative linear relationship exists between compressive strength and water absorption. Replacing 10% of traditional cement with OWA demonstrates satisfactory mechanical and durability performance in cement paste, positioning it as a promising green material for further exploration in paving block applications. Although this work concentrates on cement paste, which serves as the binding component in mortar and concrete, expanding the scope to assess the effect of OWA on the mechanical and durability of these cement-based systems in practical applications could be valuable. This approach reduces environmental impact and contributes to cost efficiency through waste valorization; nevertheless, further investigation should examine the life-cycle assessment or cost-benefit analysis to quantify these benefits. Moreover, the results highlight that OWA could also offer new possibilities for broader infrastructure applications, including pedestrian sidewalks, garden pathways, light-traffic zones, and landscing projects, where its sustainable characteristics can be leveraged to develop resilient, low-carbon construction solutions. To confirm its feasibility in paving blocks, future studies should assess actual paving block mixtures, considering the effect of aggregates and manufacturing techniques such as vibro-compaction. Furthermore, future research should evaluate the long-term durability of extensive infrastructure projects, especially in regions vulnerable to freeze-thaw cycles. Conceptualization, J.K. and H.G. ; methodology, S.G. and H.G. ; formal analysis, S.G. and H.G. ; writing--original draft preparation, S.G., A.E. and H.G. ; writing--review and editing, H.G. and S.C.; supervision, J.K. and A.E. ; project administration, H.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Data availability Statement: Data are included in this paper.