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当有接缝水泥混凝土路面由于未设置传力杆及基层支承不足发生破坏时,在横缝处增设传力杆(DBR),可改善接缝荷载传递效率和预防面板发生进一步的破坏。但得克萨斯州US59路段在DBR处理后2年内再次发生破坏。对该工程中所取芯样研究表明:传力杆底部过多的空隙阻碍了接缝处适量荷载的传递,而大量空隙的产生是回填材料固结不充分所致。为确定影响DBR中回填材料充分固结的最关键因素,采用DBR中普遍使用的速凝回填材料制作全尺寸试件模型用于研究,对以下4组变量进行了测试:回填材料拌和后放置时间;回填材料振捣时间;槽宽;最大集料尺寸。研究表明:影响回填材料充分固结的最重要因素是振捣时间,该文推荐振捣时间为20 s。同时,回填材料放置时间也是一个重要影响因素,当回填材料超过初凝时间后填入槽内,其固结性能变差。回填材料放置过久且无振捣是传力杆底部产生大部分空隙的原因。
When there is seams on the cement concrete pavement due to the failure to set up the dowel bar and the insufficient supporting of the basement, a dowel bar (DBR) is added at the transverse joint to improve the load transmission efficiency of the joint and prevent further damage to the panel. However, section US59 in Texas reoccurred within 2 years after DBR treatment. The core sample taken from this project shows that the excessive gap at the bottom of the dowel bar hinders the transmission of the appropriate load at the joint, and the large amount of void is caused by insufficient consolidation of the backfill material. In order to determine the most critical factor affecting the adequate consolidation of backfill material in DBR, a full-scale specimen model was developed using the fast-setting backfill material commonly used in DBR for the study. The following four sets of variables were tested: backfill material after mixing time ; Backfill material vibrating time; groove width; maximum aggregate size. The results show that the most important factor that affects the consolidation of backfill material is the vibrating time. The recommended vibrating time is 20 s. At the same time, the backfill material placement time is also an important factor, when the backfill material filling the tank after the initial setting time, the consolidation performance deteriorates. Backfill material placed for too long and no vibration is the bottom of the force bar to produce most of the gaps.