Airport Design-Build Bid Documents and Agency Guidance

Design-build project delivery has been embraced across several states and local agencies for large and small public transportation projects. This delivery method has also been used extensively in the construction of privately owned and operated hangars to accelerate schedule and reduce construction cost. The State of Missouri launched this research project to determine how the design-build model can be effectively utilized by general aviation airport operators in the State of Missouri in the construction of hangars using Federal Aviation Administration grant funding.

Literature review and interviews demonstrated the need for additional design-build guidance and documentation for general aviation airports in Missouri. Interviews were conducted with Department of Transportation staff, airport sponsors, consultants, and contractors to garner feedback on project concerns and lessons learned for design-build projects. The interviews demonstrated a desire by the general aviation airport operators to utilize design-build project delivery methods.

Based on these results, a design-build manual, templated documents, and checklists were generated for use by the sponsor and Missouri Department of Transportation to procure and deliver hangar projects at Missouri’s general aviation airports using design-build.

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Report number: cmr 21-008
Published: October 2021
Project number: TR202105
Authors: Glenn Goldstein, Richard Hoffman, Nicholas Patterson, and Philip Schwab

Performing organization: RS&H, Inc.

Understanding and Improving Heterogeneous, Modern Recycled Asphalt Mixes

A comprehensive research investigation was carried out to investigate the use of recycled materials in Superpave asphalt mixtures in Missouri. The investigation involved sampling of aggregates, binders, plant-produced mixtures, and field cores followed by a rigorous lab testing program. Lab testing included an extensive binder extraction and recovery (E & R) experiments, followed by a comprehensive suite of advanced binder tests. 

An attempt was made to shed light on effective strategies to iterate existing mix designs into more ‘balanced mix designs’ for modern, heterogeneous recycled mixtures in the Midwest. Different strategies were employed, such as the use of a softer virgin binder, the addition of a rejuvenator, and the employment of 5% to 20% of dry-process, engineered crumb rubber by weight of total binder. These mixes were subjected to a suite of cracking and rutting mixture performance tests to establish baseline performance, followed by four additional mix design iterations per mix (for a total of 10 investigated mixtures). The DC(T), I-FIT, IDEAL-CT, and Hamburg wheel tracking tests were used in the performance testing suite. 

Based on the results of the study, it was found that RAP, and particularly RAS, drive the need for the use of softer virgin binders to be used in modern, recycled asphalt mixtures in Missouri. Recommendations are provided with respect to the selection of softer virgin binder grades based on recycled material type and amount. Recommendations for balancing mixes with the use of rejuvenators and ground tire rubber are also provided.

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Report number: cmr 21-007
Published: October 2021
Project number: TR201807
Authors: William G. Buttlar, Magdy Abdelrahman, Hamed Majidifard, and Eslam Deef

Performing organization: University of Missouri-Columbia and Missouri University of Science & Technology