## 4 Conclusions  
The conclusions of the present work are summarized in the following. \(-\) NS added to cement as a supplementary component accelerates the heat of hydration and hydration degree of cement. Depending on the NS content, it significantly increases the water demand in the cement paste, which decreases the setting time compared to conventional concrete. \(-\) NS lowers the water demand in the mixing process of concrete, delaying the setting times and reducing the heat of hydration generated in concrete. This is related to a reduction of the mechanical strength. The addition of NS and RHA influenced concrete workability. It can be observed that, with the rise in the percentage of NS and RHA, the workability decreased. The voids and porosity of concrete were minimized by incorporating the NS and RHA. \(-\) When NS is added to the concrete mix, the amount of CSH gel formed in the matrix increases, which helps to fill the pores in concrete. Inactive NS also acts as a filler. Through these factors, NS minimizes pore volume and helps concrete to be well compacted. As a result, NS modify concrete is extremely durable. \(-\) The mechanical qualities of concrete combined with RHA and NS have improved by up to 10% over the control mix. Due to its greater specific surface, particle sizes, and porous structure, the matrix contains SF, which absorbs a large quantity of moisture and leads to the creation of CSH. The RHA absorbs moisture, which reacts with Ca\({}^{2+}\) ions in cementitious materials, enhancing the pozzolanic reaction and leading to concrete's early and long-term growth in compressive strength, splitting tensile, and flexural strength. \(-\) When increasing NS and RHA content up to 1.0% and 10%, respectively, the compressive, flexural, and tensile strength at 28 days increased, respectively. Above 1.0% NS and 10% RHA content, strength decreased. It is suggested that 1.0% NS and 10% RHA are the optimum dosages to incorporate in concrete compared to the other NS- and RHA-based concrete. Furthermore, an increase of NS and RHA led to a decrease in the compressive strength of concrete. \(-\) The microscopic test confirms that RHA particles collapse the porous structure during the grinding process, resulting in pore volume reduction. Direct or indirect sonication of NS improves the dispersion capacity of the cement matrix. Furthermore, when using direct sonication, NS is more homogenized rather than using indirect sonication. \(-\) The gray tone threshold values of aggregate and cement can be used to predict the compressive strength of concrete using an image-processing tool. \(-\) The 3D multiphysics model image can be effectively utilized for defining the pore size distribution. In addition, peaks represented by the large pore size were used to characterize materials. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Sample A** & **Sample B** & **Sample C** \\ \hline Porosity \% & 0.1784 & 0.0693 & 0.1397 \\ Average pore radius (\(\mu\)m) & 18.8447 & 17.0092 & 20.7707 \\ Standard deviation of pore radius & 14.7276 & 11.7858 & 16.9897 \\ \hline Sample A—(concrete with RHA and without NS), Sample B—(concrete with RHA and sonicated NS) and Sample C—(concrete with RHA and unsoniacted NS) [46]. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The output of MATLAB Analysis. \(-\) The proposed systematic evaluation process verifies the accuracy of predicting the pores of materials. Furthermore, the correlation between the compressive strength of concrete and pore size distribution confirms the cracking of materials. The above findings reveal the potential of using NS and RHA in concrete to enhance its efficiency and strength. Other natural fibers can also be used to improve load transfer, compressive strength, flexural strength, and ductility in concrete. This will represent the subject of a future investigation.