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This report includes the test results on aggregates from four taconite strata from the Mesabi iron range of Minnesota for concrete qualities including Los Angeles Rattler (LAR), absorption, flatness and elongation, magnesium sulfate, ASTM C 1260, and ASTM C 1293. The strata are identified as LC-8 Bed from United Taconite, LC-5 Bed from Ispat Inland/Mittal Steel (Laurentian Pit), LS-2 Bed from Ispat Inland/Mittal Steel (Laurentian Pit), and LUC Bed from United Taconite. A granite source, known to have moderately low expansion characteristics was also tested for comparison. All ledges tested well for Los Angeles Rattler and magnesium sulfate soundness. Ledges LS-2, LC-8, and LS-2 had excellent results for ASTM C 1260 and ASTM C 1293 expansion, while the LC-5 ledge performed very poorly. The Coal Creek fly ash used in the ASTM C 1293 tests mitigated ASR expansions much better than the slag mixes. As with any natural aggregate source, the physical and chemical properties of the taconite ledges vary. Because of the high variation in expansion potential, each potential concrete strata should be tested within a mine using ASTM C 1293. A Quality Control plan should be developed for each source. Specific gravity may be used to screen out potential deleterious strata, and should be performed frequently, perhaps on each blast. ASTM C 1260 tests should also be used on a frequent basis.

The primary objective of this research study is to develop an improved service life prediction model for the Minnesota Department of Transportation's (Mn/DOT's) current 60-year concrete pavement designs. Secondary objectives include understanding the behavior of these pavements with regard to maturity, slab warp and curl, and thermal expansion. These objectives will be accomplished through extensive testing of materials during construction, and conducting seasonal load response testing under controlled loads of an instrumented concrete pavement test cell (Cell 53) built to Mn/DOT's current 60-year design standards. Load response testing of traditional designs constructed in MnROAD Phase I will be used in the development of the improved life prediction model. This construction report describes the construction and material testing done on MnROAD Low Volume Road test Cell 53. A summary of U.S. and international long-life concrete pavement designs is also included.

This report analyzed the mix designs and permeability of 230 concrete mixes from Minnesota paving projects paved between 2004 and 2008. Concrete permeability was measured on cores according to ASTM C 1202, Standard Test Method for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration. Previous studies showed that aggregate gradations conforming to the 8-18 gradation specification do not always produce denser graded aggregates or concrete with better properties (higher strength, better finishability, greater freeze-thaw durability) than gradations that do not meet the 8-18 specification. Based on box plots and descriptive statistics, granite produced concrete with lower permeability than limestone and gravel. According to the Student's T-test with a 95% significance level, 7-18 graded aggregate produced concrete with significantly lower permeability than 8-18 graded and cement source and contractor both also affected permeability. According to the Student's T-test with a 90% significance level, 7-18 graded aggregate produced concrete with significantly lower permeability than gap graded mixes.

To determine whether the distress observed in MnROAD test sections was unique, researchers examined six other Minnesota concrete pavement projects of similar age and material. Similar types of distress were found but the extent of damage was not as severe and sections with base layers that adequately drained water within the joints performed significantly better.

Cell 54 was constructed in the fall of 2004 on the MnROAD low-volume loop. It is made up of eight inches of concrete underlain by Class 5 aggregate base and approximately three inches of compacted in-situ fill. Mn/DOT constructed this cell to study the properties of Mesabi-Select as coarse aggregate in concrete. This mineral aggregate that contains less iron than the ore, was obtained from overburdens in the iron ore ledges in northern Minnesota. There is no record of a previous cell constructed to study the suitability of Mesabi-Select in concrete. Cell 54 is in very good condition after five years. There are very few cracks of low severity. The types of distress found were spalling of transverse joints, longitudinal cracking, and transverse cracking. Very little joint faulting has occurred. In-situ concrete surface permeability measurements indicate that the concrete is good quality. Friction and ride quality measurements indicate that Cell 54 is in very good condition. Falling weight deflectometer (FWD) deflections at the surface and top of the base were of similar magnitude as in other doweled jointed plain concrete pavement (JPCP) test cells of similar design.

This report evaluates the third year performance of the pervious concrete test Cell 64 located in the parking lot/driveway on the south side of MnROAD's pole barn. In this report, a device and procedure to evaluate the drainability of pervious concrete and a threshold for clogging was developed. In addition, the condition of the test cell was determined by Schmidt hammer measurements and distress mapping using the Mn/DOT Pavement Distress Identification Manual. Watermark/thermocouple data was also recorded to measure freeze-thaw cycles. The number of freeze-thaw cycles at discrete depths in the pavement was then compared to impervious concrete test cells at MnROAD. The Mn/DOT and Cemstone petrographic reports on cores that had been taken 4.5 months after construction are also included, although they were outlined in previous reports. It was found that the pervious concrete of Cell 64 experienced less freeze-thaw cycles than impermeable concrete pavements of similar thickness. The main change in surface distress from the first year to the third year of service was the presence of a longitudinal crack that extended the entire cell length and raveling of the top layer of concrete. Initiating at the pole barn at a joint in the concrete curb, the crack could have propagated the length of Cell 64 due to Falling Weight Deflectometer (FWD), traffic, or thermal loading. Knowledge of pervious concrete will be greatly expanded with the study of newly constructed test cells. These cells are Cell 85, Portland Cement Concrete (PCC) pervious on sand and 89, PCC pervious on clay on the MnROAD Low Volume Road.

A maturity protocol will allow a more precise identification of the time when sufficient strength has been gained such that a pavement can be opened to traffic. This way traffic can be regulated to protect the integrity of the pavement while simultaneously streamlining construction operations by avoiding excessive initial cure periods. The overall goal of this research initiative is to develop maturity strength curves for the majority of the paving mixes used by Mn/DOT and test maturity meter implementation on several projects to observe potential difficulties/successes with their use. As such, Mn/DOT SP 6280-304, the TH-694/TH-35E interchange known as "Unweave the Weave" is one of the first Mn/DOT projects to test the implementation of maturity meters in a field setting. Based on the data from the pilot project and preliminary tasks, maturity curves are sensitive to small changes of 10 lb/yd 3 of cementitious material. It was also found that a maturity datum temperature of 0 °C was too high. Strength continued to increase even when the concrete fell below this temperature. Further studies of 15 projects over the next three years will further increase Mn/DOT's knowledge and experience with the maturity method. Included is an overview of the maturity function utilized by the data loggers.

Developed by Magnetic Imaging Tools GmbH (Dresden, Germany), the MIT Scan-2 is a nondestructive testing device that uses magnetic imaging technology to measure the position of metal dowel bars embedded in concrete. It is very quick and easy to use. Less than five minutes are needed to scan each joint and reposition the device for the next joint. The hand held computer that controls the device allows the user to see the positions of the dowel bars in the joints immediately after scanning. It also has a very easy to use analysis program called MagnoProof that uses the specified dowel locations, along with allowable tolerances, to automatically identify misaligned dowels.