PURPOSES: The objective of this study is to evaluate and compare the stiffness characteristics and seasonal variation in surface deflections of block and asphalt pavements using the light weight deflectometer (LWD) and falling weight deflectometer (FWD).
METHODS: LWD and FWD testing was conducted on block and asphalt pavement sections in a low-impact development facility, to evaluate the structural capacity and seasonal variation in asphalt pavements. To analyze the seasonal variation in stiffness characteristics, this testing was performed in October 2016, January 2017, and March 2017 in the same drop locations.
RESULTS : It was found from that the average center deflections in the asphalt and block pavements were 218 ㎛ and 2974 ㎛, respectively. The center deflections measured using FWD testing in block pavement are 15 times those measured in asphalt pavement. It was also observed that LWD deflections in block pavements were decreased by approximately 65-90% as the air temperature dropped from 20 to 4℃. The degree of reduction in block pavement was significantly higher when compared with asphalt pavement, which showed a 25- 50% reduction in deflection.
CONCLUSIONS: When using block pavements for roadways, the structural capacity of the pavement system should be considered during the design and construction stages. In block pavements, the use of low-quality material and insufficient compaction in the base and subgrade layers can induce a reduction in structural capacity, which would lead to the need for frequent repair work. A reinforcement underneath the block layer would be an appropriate measure for improving the structural support and extending the service life.

ABSTRACT
1. Introduction
2. Falling Weight Deflectometer (FWD) andLight Weight Deflectometer (LWD)
3. Comparison of FWD Deflection Characteristicsin Asphalt and Block Pavement
4. FWD Deflection Characteristics of AsphaltPavements
5. LWD Deflection Characteristics of BlockPavements
6. Seasonal Variation of Deflection in Asphaltand Block Pavements
7. Conclusions
REFERENCES

• Park Hee Mun(Korea Institute of Civil Engineering and Building Technology) | 박희문 Corresponding Author
• Lee Su Hyung(Korea Institute of Civil Engineering and Building Technology) | 이수형