# Performance Evaluation of Bedding Sand and Load Transfer Characteristic of Concrete Block Pavements
## 4 Conclusions  
In this study, we proposed LTE as the best indicator of concrete block pavement performance. To evaluate the joint and bedding sand, the material properties that affect LTE were measured. The LTE and interlocking effects of concrete block pavements were also assessed.  
The load transfer characteristics and rotational interlocking effects were measured using a non-destructive method based on the degree of joint filling, block shape, and construction pattern.  
According to the results, the shear strength of the river sand was the highest. A review of bedding sand particle sizes showed that, in the evaluation results of the internal friction angle and shear strength according to the 0.6 mm content, the difference in shear strength was not significant. It was found that the shear strength and friction angle of the material increased as the 0.075 mm content increased.  
It appeared that, in all block shapes, the greater the degree of joint filling was, the greater the LTE; the rotation was smaller, which generated a strong interlocking effect. Based on these limited test results, LTE and rotation were compared according to the block shape and pattern. For each experiment, joint filling was used as the variable. The higher the LTE and smaller the rotation, the better the performance was of the block pavement. Depending on block shape, LTE can be improved by approximately 15% and the degree of rotation is approximately 20% different. However, we believe that the LTE pattern has a negligible effect. In the case of rotation, the difference according to the pattern is also limited when the joint filling is very low. Depending on the variables, joint filling improves the LTE performance by more than 30% and rotation performance by 25%. Therefore, to derive the optimal performance of the block pavement, it is recommended to use a block with a high shape factor and fill 100% of the joint.  
In this study, LTE and degree of rotation were proposed as major performance indicators of block pavement. Additionally, factors related to performance were reviewed. The research results of measuring the performance change of block pavement according to variables through experiments can be used for block pavement design. In addition, it was possible to suggest the conditions under which block pavement can exhibit optimal performance. In the future, changes in LTE according to joint spacing, types of joint sand and bedding sand, and performance according to grading should be studied.  
Figure 12: Rotational angles according to degree of joint filling.  
**Author Contributions:** Conceptualization, W.L. and Y.-h.C.; methodology, Y.-h.C.; software, W.L.; validation, W.L. and Y.J.; investigation, Y.D.; resources, H.Z.; data curation, Y.J.; writing--original draft preparation, W.L. and Y.D.; writing--review and editing, W.L. and Y.J.; visualization, Y.D.; funding acquisition, H.Z. and Y.J. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by the National Natural Science Foundation of China (No. 51808334) and the Korea Institute of Civil Engineering and Building Technology Research Project (No. 20210140-001).  
**Conflicts of Interest:** The authors declare no conflict of interest.