Bruhn, Gordon

The Minnesota Department of Transportation (MnDOT) investigated the use of dowel bars with various anchoring methods. This report examines the characteristics of various epoxy and grout anchorage systems at the interface between new construction and existing concrete. Twelve different anchoring materials as well as various anchoring methods were studied and compared to a control using no grout. This study did not examine the effects of the number of dowels used but instead was limited to the methods and materials used to anchor the dowels. This experiment was performed on concrete panels in-house. The tube grout method exhibited the best visual and magnetic imaging results. The evaluation methods did not clearly categorize the materials in order of performance but showed advantages of cleaning the drill-hole prior to dowel placement as well as the merits and demerits of using a retaining collar. The results generally suggested the need for an actual deployment research project on actual pavement in real-world service conditions. The field experiment was reported in a separate document.

The Minnesota Department of Transportation (MnDOT) investigated the use of dowels with various anchoring methods and their effects on pavement performance. In a previous study, the characteristics of various epoxy and grout anchorage systems at the interface between new construction and existing concrete were studied using cut-out slabs brought into the Minnesota Road Research Facility (MnROAD). This investigation seeks to validate the findings of that study. Twelve different anchoring materials and methods were studied and compared to a control using no grout. This study did not examine the effects of a reduced number of dowels across a lane but rather looked at only the anchorage materials and methods. This experiment was performed on westbound lanes of Interstate 94, adjacent to the MnROAD test track. The field experimentation and monitoring involved core samples and measured ride quality, International Roughness Index (IRI), and Falling Weight Deflectometer (FWD) load transfer and fault measurement. These results supplemented the findings from the previous in-house performance categorization experiment. The control experiment, conducted without any grout or epoxy, initially displayed a notably low Load Transfer Efficiency (LTE). However, over time, there was a gradual improvement, leading to a more consistent LTE, attributed to the deployment of non-mechanical load transfer. Based on the slab thickness, the 1.25-inch dowel did not indicate any statistically significant LTE or other performance improvements over the 1-inch dowel within the anchorage types examined. Overall, the Epoxy Experimental 1 performed best while the un-grouted and unrepaired cells had the lowest performance. Moreover, no material clearly indicated characteristically low performance.