15 Sep 2022

Evaluation of a Prototype Integrated Pavement Screed for Screeding Asphalt or Concrete Crater Repairs

Abstract: Finishing, or screeding, the hot mix asphalt or rapid-setting concrete surface of a crater repair is important for rapid airfield damage recovery (RADR) since it determines the aircraft ride surface quality. The objective of RADR repairs is to expediently produce a flush repair, defined as ±0.75 in. of the surrounding pavement surface, with minimal logistical and personnel burden. Multiple screeds were previously evaluated; the most recent project proposed a prototype design of a telehandler-operated integrated screed for both small and large repairs using asphalt or concrete. This project’s objective was to finalize the prototype design and fabricate and test the prototype RADR screed. The prototype RADR screed was successful for small repairs (8.5×8.5 ft). Large repairs (30×30 ft) were generally successful with modest repair quality criteria (RQC) issues being the only notable deficiencies. Large concrete repair RQC issues were attributed to plastic formwork movement, and large asphalt repair RQC issues were attributed to compaction issues or improper roll-down factors. Methods to mitigate these factors were investigated but should be further evaluated. Overall, the RADR screed was successful from technical perspectives but, functionally, is 600-800 lb overweight. Weight reduction should be considered before entering production.

22 Apr 2021

Rapid Airfield Damage Recovery Next Generation Backfill Technologies Comparison Experiment : Technology Comparison Experiment

Abstract: The Rapid Airfield Damage Recovery (RADR) Next Generation Backfill Technology Comparison Experiment was conducted in July 2017 at the East Campus of the U.S. Army Engineer Research and Development Center (ERDC), located in Vicksburg, MS. The experiment evaluated three different crater backfill technologies to compare their performance and develop a technology trade-off analysis. The RADR next generation backfill technologies were compared to the current RADR standard backfill method of flowable fill. Results from this experiment provided useful information on technology rankings and trade-offs. This effort resulted in successful crater backfill solutions that were recommended for further end user evaluation.

1 Oct 2020

Evaluation of Solid-Polymer-Modified Asphalt Mixtures Phase 1: Construction and Performance Testing of Field Pavement Sections

ABSTRACT:  The durability of flexible pavements in cold regions is a challenge due to the impact of environmental conditions and seasonal variations. Other studies have investigated several modifiers as potential solutions to ad-dress cold climate durability of asphalt mixtures. Among these modifiers, polymer modification has shown promise. This study investigated the addition of solid polymer to asphalt mixtures to improve the performance and structural capacity of the material. Four test sections were constructed with different solid-polymer dosage rates: unmodified control, 2.5% polymer, 5% polymer, and 7.5% polymer by weight of binder. Falling weight deflectometer (FWD) testing was con-ducted at each test section to evaluate the structural capacity and to identify the performance benefits of the solid-polymer-modified mixtures. This study conducted a comprehensive analysis, including maximum pavement deflection, deflection bowl parameters, backcalculation analysis, structural number, and impulse stiffness modulus. The field investigation results revealed structural benefits in test sections with the solid-polymer-modified mixture (7%–30% increase in stiffness, depending on the dosage rate). Results suggest that solid-polymer modification could be useful in improving the stiffness of asphalt pavements without compromising durability. Therefore, further investigations should evaluate the durability of the solid-polymer-modified asphalt pavements under different environmental conditions.

28 Apr 2020

PUBLICATION NOTICE: Feasibility Investigation of Inductive Heating of Asphalt Repair Materials

Abstract: Airfield pavement repairs conducted as part of rapid airfield damage recovery (RADR) activities must utilize suitable materials to reduce the need for subsequent repairs in order to maintain an operable pavement surface. For asphalt concrete pavements, hot mix asphalt (HMA) is typically used, but this requires a fairly large operation and is less practical for small repairs (e.g., small munitions damage, potholes). Instead, cold mix asphalt (CMA) is typically used for small repairs; however, its performance under aircraft loads is generally unacceptable.  The objective of this project was to investigate the feasibility of rapidly heating small-repair quantities (e.g., 5 gal buckets) of asphalt mix to hot mix temperatures in a matter of minutes. This objective was met using 15% steel aggregate by volume to produce an inductive HMA (iHMA) that could be heated from ambient to 320°F in approximately 5 min. This technology was demonstrated at full scale with a prototype field induction heater; iHMA patch repairs were subjected to simulated F-15E traffic and exhibited comparable rutting resistance to conventional HMA, which was considerably improved relative to CMA. Overall, iHMA was found to be a feasible repair material and should be considered for additional refinement and eventual implementation.