Report on the Iowa Department of Transportation for the year ended June 30, 2012

Report on the Iowa Department of Transportation for the year ended June 30, 2012

Iowa Department of Transportation Major Items - Preliminary Quantity Report, September 17, 2013; With Addendums

Weekly letting report.

Quality Control/Quality Assurance Testing for Joint Density and Segregation of Asphalt Mixtures, TR-623, 2013

Longitudinal joint quality control/assurance is essential to the successful performance of asphalt pavements and it has received considerable amount of attention in recent years. The purpose of the study is to evaluate the level of compaction at the longitudinal joint and determine the effect of segregation on the longitudinal joint performance. Five paving projects with the use of traditional butt joint, infrared joint heater, edge restraint by milling and modified butt joint with the hot pinch longitudinal joint construction techniques were selected in this study. For each project, field density and permeability tests were made and cores from the pavement were obtained for in-lab permeability, air void and indirect tensile strength. Asphalt content and gradations were also obtained to determine the joint segregation. In general, this study finds that the minimum required joint density should be around 90.0% of the theoretical maximum density based on the AASHTO T166 method. The restrained-edge by milling and butt joint with the infrared heat treatment construction methods both create the joint density higher than this 90.0% limit. Traditional butt joint exhibits lower density and higher permeability than the criterion. In addition, all of the projects appear to have segregation at the longitudinal joint except for the edge-restraint by milling method.

Deicer Scaling Resistance of Concrete Mixtures Containing Slag Cement Phase 2: Evaluation of Different Laboratory Scaling Test Methods, TPF-5(100), 2012

With the use of supplementary cementing materials (SCMs) in concrete mixtures, salt scaling tests such as ASTM C672 have been found to be overly aggressive and do correlate well with field scaling performance. The reasons for this are thought to be because at high replacement levels, SCM mixtures can take longer to set and to develop their properties: neither of these factors is taken into account in the standard laboratory finishing and curing procedures. As a result, these variables were studied as well as a modified scaling test, based on the Quebec BNQ scaling test that had shown promise in other research. The experimental research focused on the evaluation of three scaling resistance tests, including the ASTM C672 test with normal curing as well as an accelerated curing regime used by VDOT for ASTM C1202 rapid chloride permeability tests and now included as an option in ASTM C1202. As well, several variations on the proposed draft ASTM WK9367 deicer scaling resistance test, based on the Quebec Ministry of Transportation BNQ test method, were evaluated for concretes containing varying amounts of slag cement. A total of 16 concrete mixtures were studied using both high alkali cement and low alkali cement, Grade 100 slag and Grade 120 slag with 0, 20, 35 and 50 percent slag replacement by mass of total cementing materials. Vinsol resin was used as the primary air entrainer and Micro Air® was used in two replicate mixes for comparison. Based on the results of this study, a draft alternative test method to ASTM C762 is proposed.

Development of Performance Properties of Ternary Mixtures and Concrete Pavement Mixture Design and Analysis (MDA): Effect of Paste Quality on Fresh and Hardened Properties of Ternary Mixtures, TPF-5(117), 2012

The purpose of this study was to investigate the effect of cement paste quality on the concrete performance, particularly fresh properties, by changing the water-to-cementitious materials ratio (w/cm), type and dosage of supplementary cementitious materials (SCM), and airvoid system in binary and ternary mixtures. In this experimental program, a total matrix of 54 mixtures with w/cm of 0.40 and 0.45; target air content of 2%, 4%, and 8%; a fixed cementitious content of 600 pounds per cubic yard (pcy), and the incorporation of three types of SCMs at different dosages was prepared. The fine aggregate-to- total aggregate ratio was fixed at 0.42. Workability, rheology, air-void system, setting time, strength, Wenner Probe surface resistivity, and shrinkage were determined. The effects of paste variables on workability are more marked at the higher w/cm. The compressive strength is strongly influenced by the paste quality, dominated by w/cm and air content. Surface resistivity is improved by inclusion of Class F fly ash and slag cement, especially at later ages. Ternary mixtures performed in accordance with their ingredients. The data collected will be used to develop models that will be part of an innovative mix proportioning procedure.

Iowa Department of Transportation Major Items - Preliminary Quantity Report, October 15, 2013; With Addendums

Weekly letting report.

Iowa Department of Transportation Major Items - Preliminary Quantity Report, September 17, 2013; With Addendums

Weekly letting report.

Addendum to a report on a special investigation of the Iowa Department of Transportation for the period January 29, 1994 through June 30, 2013

Addendum to a report on a special investigation of the Iowa Department of Transportation for the period January 29, 1994 through June 30, 2013

Iowa Department of Transportation Major Items - Preliminary Quantity Report, November 19, 2013; With Addendums

Weekly letting report.

Iowa Department of Transportation Major Items - Preliminary Quantity Report, December 17, 2013; With Addendums

Weekly letting report.

Evaluation of Bias in the Hamburg Wheel Tracking Device, RB00-010, 2013

As the list of states adopting the HWTD continues to grow, there is a need to evaluate how results are utilized. AASHTO T 324 does not standardize the analysis and reporting of test results. Furthermore, processing and reporting of the results among manufacturers is not uniform. This is partly due to the variation among agency reporting requirements. Some include only the midpoint rut depth, while others include the average across the entire length of the wheel track. To eliminate bias in reporting, statistical analysis was performed on over 150 test runs on gyratory specimens. Measurement location was found to be a source of significant variation in the HWTD. This is likely due to the nonuniform wheel speed across the specimen, geometry of the specimen, and air void profile. Eliminating this source of bias when reporting results is feasible though is dependent upon the average rut depth at the final pass. When reporting rut depth at the final pass, it is suggested for poor performing samples to average measurement locations near the interface of the adjoining gyratory specimens. This is necessary due to the wheel lipping on the mold. For all other samples it is reasonable to only eliminate the 3 locations furthest from the gear house. For multi‐wheel units, wheel side was also found to be significant for poor and good performing samples. After eliminating the suggested measurements from the analysis, the wheel was no longer a significant source of variation.

Opérette Czardashe : oh ya ; Opérette Czardashe : air de Champagne / Newart Hanoum, chant [acc. orch.]

[Traditions. Asie. Turquie]