6 Apr 2023

Naval Expeditionary Runway Construction Criteria: P-8 Poseidon Pavement Requirements

Abstract: A full-scale airfield pavement test section was constructed and trafficked by the US Army Engineer Research and Development Center to determine minimum rigid and flexible pavement thickness requirements to support contingency operations of the P-8 Poseidon aircraft. Additionally, airfield damage repair solutions were tested to evaluate the compatibility of those solutions with the P-8 Poseidon. The test items consisted of various material thickness and strengths to yield a range of operations to failure allowing development of performance predictions at a relatively lower number of design operations than are considered in traditional sustainment pavement design scenarios. Test items were trafficked with a dual-wheel P-8 test gear on a heavy-vehicle simulator. Flexible pavement rutting, rigid pavement cracking and spalling, instrumentation response, and falling-weight deflectometer data were monitored at select traffic intervals. The results of the trafficking tests indicated that existing design predictions were generally overconservative. Thus, minimum pavement layer thickness recommendations were made to support a minimum level of contingency operations. The results of full-scale flexible pavement experiment were utilized to support an analytical modeling effort to extend flexible pavement thickness recommendations beyond those evaluated.

6 Apr 2023

Eelgrass Functions, Services, and Considerations for Compensatory Mitigation

Abstract: Coastal-marine eelgrass habitat is a critical resource within New England and throughout the world. Eelgrass habitat provides functions and services including providing structure, biogeochemical cycling, erosion reduction, habitation provision, and water quality improvement. Declines in eelgrass distribution are often due to anthropogenic processes impacting temperature and water quality. Declines in distribution and abundance highlight the importance of protecting the existing eelgrass, improving environmental conditions allowing for ecosystem restoration, and identifying viable in-kind and out-of-kind compensatory mitigation measures. Considering the limited availability of New England sites for in-kind compensatory mitigation, additional approaches for out-of-kind compensatory mitigation should be considered. These include (1) creation of alternative plant or kelp habitat, (2) using a multi-pronged, multi-habitat and structure approach, (3) contributing to the development of water quality improvement initiatives to encourage current eelgrass bed expansion over time, (4) reduce physical impacts to eelgrass habitat, (5) and identifying locations for future eelgrass habitat suitability based on climate predictions and investing to create future compensatory mitigation habitat in these locations.

5 Apr 2023

4D Printing Structures for Extreme Temperatures Using Metakaolin Based Geopolymers

Abstract: Geopolymers (GPs) are a class of amorphous, aluminosilicate-based ceramics that cure at room temperature. GPs are formed by mixing an aluminosilicate source, which is metakaolin in this case, with an alkali activator solution, which can be either sodium or potassium water glass. GPs have attracted interest for use in structural applications over the past few decades because they have superior mechanical properties to ordinary Portland cement (OPC). Additionally, they can tolerate much higher temperatures and produce a fraction of the CO₂ compared to OPC. This project aims to develop geopolymer composites for 4D printing (the fourth dimension being time) and test their mechanical properties. Rheology and the effects of curing in ambient conditions will be evaluated for fresh geopolymer. Freeze-thaw resistance will be evaluated on potentially printable composites for extreme temperature resistance, etc.

4 Apr 2023

Character-Defining Features of the Buffalo South Mole (South Pier), NY

The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. The precursor to the Corps of Engineers erected the mole (a.k.a., the south pier) in the early 1820s at the entrance to the Buffalo harbor. The area on top of and surrounding the mole was modified through the past two hundred years, many of the character-defining features remain including the stone retaining walls, talus, stairs, and lighthouse identified in plans and drawings from the period of construction. Notably lost is the stone tow path, or banquette, and the stone incline on the south side of the mole is no longer visible. The researchers recommend a period of significance of c. 1820 through 1972 (50 years) since the mole has continued its original use of keeping the entrance to the Buffalo River open for freight and recreational boating traffic through the present day.