# Experimental Study on a Prediction Model of the Shrinkage and Creep of Recycled Aggregate Concrete
## 5 Conclusions  
1. The development law of the shrinkage and creep of RAC is similar to that of ordinary concrete. At 180 days, compared with ordinary concrete, the shrinkage of group I RAC with a substitution rate of 50% and 100% was increased by 26% and 48%, respectively, and the group II RAC was increased by 22% and 47%, respectively. When the load was 180 days old, compared with ordinary concrete, the creep rate of group I RAC with a substitution rate of 50% and 100% was increased by 19.6% and 39.6%, respectively, and group II was increased by 23.6% and 44.3%, respectively. With the increase of the replacement rate of recycled aggregate, the shrinkage and creep of RAC increased significantly, which indicates that the substitution rate is an important factor affecting the shrinkage and creep of RAC, and the water-cement ratio has more significant effects on the creep of RAC.
2. The effect of the substitution rate on the shrinkage and creep of RAC is caused by the adhesion of mortar. As the substitution rate increases, the porosity of the attached mortar increases the degree of concrete shrinkage. The increase of the water-cement ratio leads to an increase in the proportion of the attached mortar in the RAC. More adherence of the mortar pores weakens the restraint performance of the RAC, which in turn reduces the resistance of the RAC to creep.
3. The key difference between recycled aggregate and natural aggregate is the difference in the content of the attached mortar. In this paper, the contraction point was used to calculate the shrinkage strain and creep coefficient of the RAC shrinkage model, and the attached mortar increase coefficient method was also used. The calculated value of the model takes into account the effect of the recycled mortar itself on the shrinkage and creep of the recycled concrete. The difference between the calculated value and the experimental value is small and can meet the accuracy requirements well.
4. Based on the difference of the attached mortar, effective shrinkage and creep of RAC can be established, and the shrinkage and creep of RAC will show a different development trend from ordinary concrete as the age increases. At the same time, according to the same research ideas, a complete prediction model of the shrinkage and creep of RAC with a full-service life cycle can be established, and the calculation method of the long-term deformation of RAC with significant influence on shrinkage and creep can be carried out.  
[PERSON] and [PERSON] were responsible for the writing of this article. [PERSON] and [PERSON] were responsible for the evaluation and comments of the paper content, and [PERSON] was responsible for the organization of the article data.  
This research was funded by [the Natural Science Foundation of China] grant number [51878546], [the Shaanxi Science and Technology Innovation Base] grant number [2017 KTPT-19], [the Shaanxi Province Innovative Talent Promotion Plan Project] grant number [2018 KJXX-056], the Shaanxi Provincial Key Research and Development Program] grant number [2018 ZDCXL-SF-03-03-02].  
The support from the following fund projects is highly acknowledged: (1) the Natural Science Foundation of China (51878546); (2) the Shaanxi Science and Technology Innovation Base (2017 KTPT-19); (3) the Shaanxi Province Innovative Talent Promotion Plan Project (2018 KJXX-056); (4) the Shaanxi Provincial Key Research and Development Program (2018 ZDCXL-SF-03-03-02).  
All authors declare that this article has no conflict of interest, and the data (including figures, tables) and other relevant information used in the article are approved by all authors. The correspondent authors exercise power over the article on behalf of all authors.