Discrete element simulation on rolling process of PCM-clay with different crystallinity

Paraffin-based phase-change-material mixed clay (PCM-clay) provides a potential way to solve the problem of anti-freezing and temperature control during the construction of clay core wall in cold regions in winter. However, the phase change of PCM with different crystallinity at different temperatures leads to different compaction properties of PCM-clay. The control standards of compaction parameters of PCM-clay with different PCM crystallinity need to be further studied. Considering that the field rolling test is not only costly, but also difficult to control the test temperature of PCM to reach the set crystallinity under the changeable environment. Accordingly, PFC 3D software was used to establish the rolling discrete element model of PCM-clay with different PCM crystallinity according to the similarity rate of roller and load simulation. The validity of the discrete element model of PCM-clay was verified by the indoor compaction test results. The influence of different rolling parameters on the compaction quality of PCM-clay was analyzed, and then the control standard of PCM-clay rolling parameters under different PCM content and different PCM crystallinity was given. The results show that when the vibratory force is too small, it is difficult to achieve the compaction effect of large vibratory force even if the number of rolling passes is increased. Properly increasing the vibratory force is beneficial to compaction. The increase of the crystallinity of PCM will reduce the dry density of PCM-clay. However, increasing the number of rolling passes, reducing the rolling speed, reducing paving thickness and other measures can effectively improve the compaction effect of PCM-clay after PCM crystallization, and achieve the maximum dry density of uncrystallized PCM. This study can provide a new method for analyzing the compaction quality of PCM-clay at different construction temperatures, and also provide a theoretical basis for reasonably determining the compaction quality control of PCM-clay in core wall with different PCM crystallinity.