Lulu Edwards

Stiffness-Based Assessment of Pavement Foundation Materials Using Portable Tools

Traditional pavement quality assurance has focused on soil density and moisture content. Implementation of new mechanistic design methods calls for measuring the resilient modulus of constructed layers to determine whether it matches the modulus used during the pavement design process. Several tools have been marketed for this purpose in recent years. Eleven soil test beds were constructed at the U.S. Army Engineer Research and Development Center to evaluate three of these tools. The study showed that the tools were simple to use and generally obtained repeatable results, but additional information regarding the true nature of the modulus measured by these tools was required to implement their use.

Rapid-setting flowable fill performance in cold weather for airfield damage repair

This report documents the repair process of five craters in cold weather utilizing rapid-setting flowable fill (RSFF) and rapid-setting concrete (RSC). The work discussed herein supports the Rapid Airfield Damage Recovery (RADR) Program, in which the main objective is to develop capabilities to rapidly repair damaged airfield pavements for the full spectrum of operational scenarios. The purpose of this report is to document constructability, to collect early-age properties pertinent to the ability of these crater repair techniques to carry aircraft traffic, and to measure performance by exposing crater repairs to simulated aircraft traffic. Crater repair testing occurred at the Frost Effects Research Facility at the ERDC Cold Regions Research and Engineering Laboratory in Hanover, NH. Results showed RSFF could be a suitable cold-weather backfill. Aluminum sulfate was tested as an additive for use in cold weather, but repairs utilizing it did not perform well. The most efficient manner of using RSFF in cold weather was to heat the mix water. With heated mix water, a rapidly placed pavement repair was able to withstand 100 passes of an aircraft load cart after approximately 2 hr of cure time where RSFF was the backfill and RSC was the cap. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/GSL TR-18-26 iii

Evaluating Sustainability of Face Bricks for Road and Airfield Pavements

The feasibility of using face bricks as an alternative to concrete or asphalt paving was evaluated for lightweight and heavyweight vehicle traffic. Paving materials and equipment can be scarce in expeditionary environments, so the use of bricks recycled from existing infrastructure may provide a local resource for constructing pavements suitable for meeting the militarys mission requirements. The field testing documented in this paper follows a laboratory study in which a series of strength and characterization tests were conducted on selected face bricks and brick pavers. The success of the laboratory testing led to the full-scale field evaluation of the face and paver bricks trafficked with a commercial dump truck load of approximately 24.5 t and then trafficked with a 20.4 t single-wheel C-17 aircraft load cart. The field testing indicated brick-paved roads constructed with a moderately high-strength base are capable of sustaining more than 10 000 passes of truck traffic without failure. The same brick-paved roads were not capable of withstanding C-17 aircraft traffic. Further results from the evaluation are presented and include material characterization test data, rut depth measurements, wheel path and cross-section profile measurements, instrumentation response data, and forensic assessments.

Airport Rubber Removal: A Comparison of Ultra-High Pressure Water Runway Rubber Removal Systems

Runway rubber removal is a maintenance function employed to ensure safe landing areas for aviation operations. Rubber deposits accumulate on runway areas where aircraft tires touchdown and braking occurs. This tire rubber build up occludes pavement microtexture and macrotexture, causing a significant loss in available skid resistance during wet conditions. Reduction of available pavement microtexture in a wet environment prevents the development of adhesional friction, which can result in viscous hydroplaning. Reduction of pavement macrotexture prevents the removal of bulk water from the tire-pavement contact area and also prevents the development of the hysteresis frictional component. To restore friction to safe levels for aircraft operations, rubber must be periodically removed. Several techniques for rubber removal are available. Waterblasting is a proven surface decontamination technique which employs the use of high or ultra-high pressure water (UHPW) to blast rubber deposits from the runway surface. This effort provides a performance-based comparison between three commercially available UHPW waterblasting systems. The evaluation was conducted on an ungrooved Portland Cement Concrete (PCC) runway with heavy rubber contamination along the touchdown and breaking zones. Several testing equipment such as Circular Track Meter (CTM) and Dynamic Friction Tester (DFT) were used to characterize the surface properties of the runway before and after rubber removal. The measurements were used for statistical pairwise comparative analysis of International Friction Index (IFI), speed constant and Mean Profile Depth (MPD). Treatment effect analysis of pre-measured and postmeasured data revealed that UHPW systems improved the surface texture properties by at least 40% regardless of the decontamination equipment.

Verification of a 3-D terrain mapping LADAR on various materials in different environments

A field validation of a laser detection and ranging (LADAR) system was conducted by the U.S. Army Engineer Research and Development Center (ERDC), Vicksburg, Mississippi. The LADAR system, a commercial-off-the-shelf (COTS) LADAR system custom-modified by Autonomous Solutions, Inc. (ASI), was tested for accuracy in measuring terrain geometry. A verification method was developed to compare the LADAR dataset to a ground-truth dataset that consisted of total station measurements. Three control points were measured and used to align the two datasets. The influence of slopes, surface materials, light, fog, and dust were investigated. The study revealed that slopes only affected measurements when the terrain was obscured from the LADAR system, and ambient light conditions did not significantly affect the LADAR measurements. The accuracy of the LADAR system, which was equipped with fog correction, was adversely affected by particles suspended in air, such as fog or dust. Also, in some cases the material type had an effect on the accuracy of the LADAR measurements.