Assessment of rapid impact compaction for transportation infrastructure applications

Despite being identified as a geoconstruction technology applicable to transportation infrastructure applications, rapid impact compaction (RIC) has yet to be utilized on a transportation infrastructure project. Both technical and nontechnical obstacles, such as a lack of performance data, have impeded the introduction of RIC into the transportation sector. Each obstacle requires mitigation before RIC can be incorporated into the transportation sector. The goal of this research was to evaluate RIC for civil engineering applications in the transportation sector and mitigate the obstacles impeding the use of RIC within the transportation sector. The objectives that were sought to achieve this goal include expanding the RIC knowledge base; presenting a detailed case history of a commercial RIC project; and assessing the applicability of RIC\u27s design, QC/QA, and specification procedures to transportation infrastructure projects. RIC is a well established technique within the commercial sector. An ample amount of commercial case histories and data pertaining to RIC performance, induced vibrations, and cost are currently in existence. The current procedures for design, QC/QA, and specification within the commercial sector will require improvement before application to transportation infrastructure projects. This research has addressed each of the obstacles preventing use of RIC within the transportation sector and has either partially or fully mitigated each obstacle. Additional future strategies for partially mitigated obstacles have been proposed. With fewer obstacles and a greater knowledge base, transportation agencies will have greater confidence in employing RIC for transportation projects

Construction of MSE Wallsfor INDOT Projects

Due to their lower costs, Mechanically Stabilized Earth (MSE) walls have become the preferred type of retaining structure by transportation agencies across the United States. However, costs associated with the repair or reconstruction of poor-performing MSE walls can outweigh their initial cost savings. Therefore, MSE walls must be properly constructed in accordance with agency specifications and manufacturer guide- lines. This presentation outlines the requirements and best practices involved with constructing MSE walls for INDOT projects

Using the Light Weight Deflectometer for Performance-Based Quality Assurance Testing of Cement Modified Subgrades

This report documents the findings from SPR-4230 (Alternative Quality Assurance Methods for Compacted Subgrade). The main objective of SPR-4230 involved establishing performance-related quality assurance (QA) test methods for pavement subgrade construction. Because INDOT generally prefers specifying subgrade treatment type IBC (i.e., 14-in. cement modified subgrade), this study focused on performance-based QA test methods for constructing cement modified subgrade. Moreover, INDOT prefers using light weight deflectometer (LWD) for chemically modified subgrade construction acceptance, so this study aimed to use LWD deflection measurements as performance-related construction acceptance criteria. A laboratory study was performed to relate LWD deflections with resilient modulus that is the key subgrade performance-related parameter in pavement design. In addition, LWD deflections were related with unconfined compressive strength increase that is the key parameter in chemical soil modification mix design. A rigorous field study consisting of LWD testing and falling weight deflectometer (FWD) testing at INDOT new pavement construction sites was conducted to verify the laboratory developed relationship. Recommendations for implementing results of this study into cement modified subgrade construction acceptance is provided, as are recommendations for future research

SPR-4230: Alternative Quality Assurance Methods for Compacted Subgrade

This presentation introduces and summarizes SPR-4230 (Alternative Quality Assurance Methods for Compacted Subgrade), which aims to establish performance-based QA test methods for subgrade treatment construction. The presenter will review the current state of subgrade treatment QA testing methods and then discuss proposed QA testing methods that SPR-4230 is currently assessing. Because SPR-4230 is not scheduled for completion until March 2020, preliminary results and future work for the project will be presented

Is It Scientific? Viewer Perceptions of Storm Surge Visualizations

Scientists and coastal risk managers use semi-realistic visualizations of storm surge connected to hydrodynamic models to make projected impacts engaging and accessible. Such visualizations do not fit within established frameworks for visualizing risk because they add representational detail and may imply more certainty than exists regarding outcomes. This study explores how audiences regard these visualizations in relation to perceived representational norms for scientific graphics and visualizations. Online survey respondents (735 experts and members of the general public, primarily in Rhode Island and the northeastern United States) were asked about characteristics that make a representation “scientific.” Results demonstrate differences in norms emphasized by experts and the public, and that the persons and institutions creating the visualization may influence perceptions of legitimacy more than the style of the visualization. This may increase the potential of visualizations to be misleading and may foster perceptions that scientists are engaged in advocacy