The purpose of this study was to determine the impact of a magnesium chloride-based deicer, a sodium chloride-based deicer, and the major salts contained in these deicers on seed germination and seedling growth and development of fifteen species of grasses and forbs native to Colorado. Seven of the fifteen species performed well at the low and medium concentrations of the salts and solutions; these are plants that can likely germinate in roadside areas.
An adequate longitudinal joint tie bar system is essential in the overall performance of concrete pavement. Excessive longitudinal joint openings are believed to be caused by either inadequate tie bar size or spacing or improper tie bar installation. If designed and installed properly, tie bars prevent the joints from opening and consequently improve load transfer efficiency between slabs and between slabs and shoulders, resulting in increased load carrying capacity. CDOT should adopt the mechanistic-empirical tie bar design procedure developed in this study.
Following a rigid set of testing protocols, data is being collected on highway traffic noise characteristics along with safety and durability aspects of the associated pavements. The overall goal of this research project is to develop and execute a comprehensive, long-term study to determine if a particular pavement surface type and/or texture can be successfully used in Colorado to help satisfy FHWA noise mitigation requirements.
The objective of this interim report is to provide a synopsis of the progress made after one year on the feasibility of using waste tires (crumb rubber) in the construction of asphalt pavements.
This final report is intended to provide information regarding the performance of crack sealants supplied and installed by three manufacturers for experimental use in a three-year evaluation of in-service pavements on three Colorado highways.
This report analyzes the Quality Control/Quality Assurance (QC/QA) data for Portland cement concrete pavement (PCCP) awarded in the years 2000 through 2009. Analysis of the overall performance of the projects is accomplished by reviewing the Calculated Pay Factor Composite (CPFC) and Incentive/Disincentive Payments (I/DP). Analysis of each of the test elements: thickness, compressive strength, sand equivalent, and flexural strength is also completed. The results of the evaluation are presented in tables, figures, and reports. The overall quality of PCCP evaluated is very high. The quality levels in each of the elements are approaching the maximum of 100%. The pay factors for the individual elements are also close to their maximums. The material being produced is well above the minimum standards set by the specifications.
This report analyzes the quality control/quality assurance (QC/QA) data for hot mix asphalt (HMA) using voids acceptance as the testing criteria awarded in the years 2000 through 2010. Analysis of the overall performance of the projects is accomplished by reviewing the Calculated Pay Factor Composite (CPFC) and Incentive/Disincentive Payments (I/DP). Analysis of each of the elements: asphalt content, voids in mineral aggregate (VMA), air voids, mat density, and joint density is presented in tables, figures, and reports. Various data groupings are used to evaluate the data including: year, region, and grading. The specification and the projects are performing reasonably well. The results for the data show that quality of the projects is remaining fairly consistent. No definite upward or downward trends can be seen in the data. Over the eleven-year time period more projects have received incentive payments than disincentive payments. The average CPFC over the eleven years evaluation is 1.00569. The quality levels in the individual elements are at relatively high levels. The VMA and mat density elements show the best results being above 93 percent within the specification limits. The asphalt content and air voids elements are at approximately 90 percent. The joint density pay factor is under 1.0 but is expected to rise as contractors gain experience in this area.
Cost-effective strategies were developed and identified to CDOT Highway Maintenance Managers to reduce rest area operational costs while conserving finite natural resources. Initial cost analysis indicates that reduced operational costs can be realized by implementing water conservation practices (waterless urinals, water harvesting, irrigation, energy conservation and alternative energy practices, and re-use and recycling of solid waste and landscaping transition toward xeriscape practices).
