Minnesota Department of Transportation
This report describes the 7-year performance of the 60-year concrete design test cell (Cell 53) built in 2008 in the MnROAD Low Volume Road). Many characteristics of this 115-foot cell, two 12-feet wide lanes, 12 inch thick dowelled concrete test have exhibited insignificant change in performance criteria over the 5-year period. . The test cell maintained adequate skid resistance since it was constructed in 2008. Transverse joint monitoring and fault measurements also indicated insignificant faulting over the period of review. In many cases, measured properties in the inside lane of Cell 53 were significantly different from outside lane. The International Roughness Index (IRI) was not initially low but has remained relatively constant. Additionally, a slight disparity of IRI between the inside (traffic) lane and the outside (environmental) lane was evident. The IRI in the inside lane was consistently higher than the outside lane. Seasonal deflection basins created for both summer and spring dates soon after construction in 2009 and similar summer and spring dates in 2013 showed deflections below 100 microns, which also suggests good performance. The test cell displayed excellent load transfer at all of the transverse joints tested in this research. The average load transfer was approximately 0.85, which was in some cases over four times as high as another MnROAD concrete pavement test cell which was undoweled and in poor condition. The load transfer in the 60-year design cell had not shown significant decrease over time. Researchers used the Evaluation of Layer Moduli and Overlay Design (ELMOD) to determine the layer properties of the pavement test cell. Again, similar dates in both spring and summer seasons were compared for the year 2009 and 2013. Summer results exhibited a slight decrease in calculated Moduli values for the base, subbase and subgrade layers, for both the inside and outside lane. This slight decrease over the period was not interpreted as failure in the base layers. Seven years of monitoring reveal that 60-year design concrete pavement test cell has not shown any performance issues apart from those inherent in the construction process. Most Importantly, evidence of lesser strain in the concrete when compared to thinner pavements designed for a shorter service life at the research facility.
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