# Effect of Aggregate Size on Recycled Aggregate Concrete under Equivalent Mortar Volume Mix Design
## 4 Conclusions  
In this paper, the effect of the size of the original aggregates in recycled aggregates on the fresh and hardened properties of recycled aggregate concrete was evaluated. Based on the test results, the following conclusions were drawn:  
* Higher residual mortar content was observed in the smaller size RCA, resulting in higher water absorption and lower specific gravity. The higher residual mortar content increased the size gap between the OA and RCA. * The EMV mix design caused unfavorable workability of RAC in the fresh state, but it could improve the mechanical properties of RAC in the hardened state to a level similar to that of NAC. * When the particle size distribution was determined based on the size of OA in RCA, the compressive strength, tensile strength, and elastic modulus of RAC designed by the EMV mix design were improved. Figure 8: Correlation between compressive strength and elastic modulus of recycled aggregate concrete. * The RAC-OA series considering the size of OA showed stronger correlations between the compressive strength and splitting tensile strength, and the compressive strength and elastic modulus than the RAC-AP series considering the size of RCA itself. Although the study presented was based on only two RCA samples from two different sources, they differed in their primary properties (absorbency, density, and residual mortar content) quite significantly, so they can be said to represent a wider range of potential RCA properties. The EMV mix design affects the results of the experiment because it practically (i) reduces the amount of new mortar and (ii) increases the amount of RCA, which naturally leads to their change. Provided that sufficient technical parameters are achieved, this would lead to savings in materials, especially cement and natural aggregate, and also to an increase in the recycling rate of construction and demolition waste. The principle of determining the mix proportions by the EMV method is applicable to any concrete with RCAs having a certain proportion of residual mortar. However, further studies should be performed to generalize the results. This applies both to RCA from other sources and to the study of the EMV mix design principles in relation to the effect of OA size. Further research could also cover the use of the method to completely replace NA with RCA. Such substitutes are widely investigated by standard mix design methods and usually result in reduced mechanical properties (e.g., 20-25% reduction in compressive strength [61], up to 25% in tensile strength, and up to 15% in elastic modulus [62]). Conceptualization, J.K. and A.S.; Methodology, J.K.; Investigation, H.J. ; Data curation, H.J. and J.K.; Writing--original draft preparation, H.J. and J.K.; Writing--review and editing, A.S.; Supervision, A.S. All authors have read and agreed to the published version of the manuscript. This research was carried out within the project of Slovak Scientific Grant Agency VEGA (Grant No. 1/0524/18) \"Effective use of alternative aggregate of lower quality through modern concrete preparation techniques\". Not applicable. The authors declare no conflict of interest. This appendix shows the EMV mix proportioning procedure of RAC1-AP-25. 1. Proportioning NAC based on the ACI mix design:  
Weight of water in NAC : \(W_{\rm NAC}^{\rm NAC}=175\) kg  
Weight of cement in NAC : \(W_{\rm C}^{\rm NAC}=389\) kg  
Oven - dry weight of fine aggregate in NAC : \(W_{\rm OD-FA}^{\rm NAC}=720\) kg  
Oven - dry weight of NA in NAC : \(W_{\rm OD-NA}^{\rm NAC}=1003\) kg
2.