Saw cutting (or not) of joint spacing in roller-compacted concrete pavement

Natural cracking in unjointed roller-compacted concrete pavement (RCCP) may exhibit poor load transfer efficiency (LTE) across the cracks, leading to the occurrence of faulting, further cracking and excessive deflection, and a dramatic decrease in pavement service life. The aim of this study is to enable pavement designers to make the right decision as to whether or not to saw cut joints for RCCP. Analytical approaches to predicting the natural crack spacing for unjointed RCCP are considered and verified with data observed in the field. The predictive model response for different locations in South Korea was simulated to consider climate effects on natural crack spacing. Furthermore, measurements of LTE using a falling weight deflectometer across natural cracks in RCCP in relation to the crack opening were performed and a back-calculated joint spacing for adequate LTE was derived. Based on the results obtained, the analytical model for natural crack spacing provided accurate results compared to field data. The results also showed that the natural crack spacing is sensitive to ambient temperature and placement time. These spacings were too large to maintain adequate LTE and significantly decrease the LTE across RCCP cracks. Therefore, it was found that saw cutting of the joint spacing is required.