## 3 Results and Discussion
### Abrasion Resistance Versus Different Macro-Textures  
Figure 15 shows the cumulative abrasion results for different similar micro/macro-texture mixes to study their abrasion resistance. Statistical analysis of variance (one-way ANOVA) shows this resistance has not significantly different for different approximately similar macro-textures; it is the lowest for the big seeding because of the extraction and separation of weakly bonded 4.75-9.5 mm seeded aggregates from the low-thick cement paste on the RCC surface. Contrarily, it has a significant difference for all mixtures, so that mix containing manufactured silica sand is a suitable candidate when durable high abrasion resistance micro-textures are desired. The next mix with high abrasion resistance has been made with a combination of manufactured silica/calcareous sand.  
Figure 16 compares MTD results of different mixing proportions and different macro-textures; although changes in the mass loss due to abrasion may not well indicate which macro-texture can be affected, results show that the best one is the small stamping and the worst is the small seeding. Enough MTD on the surface texturing is crucial to provide adequate surface friction to meet the safety requirements, particularly under wet conditions, and reduce hydroplaning potential, splash and spray that scan highly reduce the visibility. Nevertheless, excess MTD will affect other functional issues such as the tire-pavement noise pollution and rolling resistance that increases fuel consumption. Hence, it can be concluded that the friction-noise trade-off and optimum MTD determination to enhance the RCCP efficiency should be considered as vital necessities. Based on NCHRP-634 [46], high levels of friction can be achieved with the ground, grooved, and tined textures, especially if the good-quality aggregate is used in the concrete mix; however, it can become inadequate if less than 0.8 mm-MTD polish-susceptible aggregates are used at the time of construction [46] (Minnesota Astrotur Texture [47] suggests MTDs \(\geq\) 1 mm). Although the literature does not clearly specify the MTD and noise thresholds, there are facts that help find the proper texture. [PERSON] et al. [48] believe that negative textures have better acoustical performance than positive ones. Since investigations of different macro-texture properties, especially their average depth, show that many of them have depths in the  
Figure 15: Comparison of abrasion resistance of different micro/macro-texture.  
range of 0.2-1.4 mm [46; 47; 49], this study has used MTDs in the range of 0.8-1.5 mm to select the proper macro-texture (Figure 16).  
Effective micro-textures generally provide adequate surface friction on dry pavement surfaces at all speeds and on wet surfaces only at slower speeds, whereas macro-textures typically provide adequate friction on wet pavement surfaces at high speeds [50]. To have wearing-/polishing-resistant concretes, micro-textures are usually generated by fine aggregates, 25% of which (minimum) should be siliceous [51]; therefore, the combined sand mixture is preferable.  
Results in Figure 16 show that the negative macro-texture mixes made by combined sand (natural/manufactured and siliceous/calcareous) with MTDs in the range of 0.8-1.5 mm such as big stamping and one-way brooming are proper candidates to achieve durable RCCP surfaces. In addition, all mixes with big and medium seeding macro-textures approximately approved the MTD thresholds.