## 6 Conclusions  
An intensive review on the impact of design parameters was conducted in order to make a simplified design procedure for the design mix of SCC made with recycled aggregates. The overall summarized report on the review is stated below:  
* Increase in W/C ratio results in a decrease in compressive strength and split tensile strength. A W/C ratio greater than 0.6 is observed for Family V and VI. Split tensile strength greater than 4.5 MPa is obtained for Family II, III, and IV with a lower W/C ratio.
* W/B ratio less than 0.30 produces higher compressive strength and, simultaneously, higher split tensile strength. Further increase in the W/B ratio results in a decrease in compressive strength and split tensile strength.  
Figure 18: Relationship between compressive strength and split tensile strength which belongs to different families of SCC with RA according to the literature.  
* The lower the TA/C ratio is, the higher the compressive strength will be. However, there is a controversial result observed with respect to split tensile strength. When the TA/C ratio decreases in compressive and split tensile strength, the optimum range for TA/C ratio with respect to compressive and split tensile strength is 3 to 9.
* For most of the literature, it was found that FA/CA ratio lies in the range of 1.5 to 3.0 for compressive and split tensile strength. There is no constant relationship between strength and FA/CA ratio but it plays a vital role in fresh concrete properties for SCC.
* There is no constant relationship between SP and strength for SCC.
* When the W/S ratio is lower, the compressive and split tensile strength becomes higher. Higher W/S ratio results in lower compressive and split tensile strength.
* Higher compressive and split tensile strength is obtained for the lower-level replacement of NFA by RFA. However, 100% replacement of NFA by RFA results in compressive strength in a range of 40 MPa to 65 MPa and split tensile strength in a range of 2.5 MPa to 3.5 MPa.
* Higher compressive strength is obtained for 100% replacement of NCA by RCA. Most researchers had used the replacement of NCA by RCA up to 60% relative to the obtained compressive strength of more than 35 MPa. The increase in replacement of NCA by RCA results in a decrease in split tensile strength.
* For several families, there is cluster formation in family III and V observed for compressive and split tensile strength. For family I, II, and IV, there is linear relationship and family VI demonstrates a non-linear relationship.  
Detailed investigation on the effect of design parameters on the strength properties of SCC with recycled aggregate will help researchers and engineers to develop a minimum requirement for a SCC mix with recycled aggregates. It also helps to develop a guideline for field engineers and assists the progress of several international standards and codes.  
Conceptualization, P.J., [PERSON], [PERSON]-d.P. and [PERSON]; investigation, [PERSON] and [PERSON]; writing--original draft preparation, [PERSON], [PERSON] and [PERSON]; writing--review and editing, [PERSON], [PERSON]-d.P., [PERSON] and [PERSON]; supervision, [PERSON], [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript.  
This research was funded by University of Leon, grant number BB253.  
Not applicable.  
The authors state that they have no conflicts of interest.