This paper presents a study conducted to characterise seismic modulus growth in lime-stabilised soil (LSS) throughout 28-day curing using free-free resonance testing. The motivation for this study is to explore the prediction of 28-day modulus and strength from seismic modulus data collected during early curing, and in general to investigate the efficacy of seismic testing as a method of quality assessment for LSS. Measured E and G growth ranged from 250% to 900% during curing for the three soils. Modulus values and growth in modulus were significantly influenced by mineralogy and soil processing. The growth in seismic modulus for each soil exhibited a power law relationship with curing time. The 28-day modulus was estimated within 8% error for two soils using early curing modulus data, that is, through 7 days. Seismic modulus was found to correlate linearly with unconfined compressive strength (q u ) throughout curing. The proportionality of E and q u remained constant during curing for each soil beyond day 3. The study shows that early curing seismic data -that is, through 7, 8 or 9 days -is capable of providing a good estimate of 28-day E and q u if the variability is reasonable (here, range/mean < 0 . 5).

Given the schedule pressure of lime-stabilized soil construction, many agencies specify the use of elevated temperature (e.g., 41°C), shorter duration (e.g., 5-7 days) accelerated specimen curing for unconfined compressive strength (q u) testing and acceptance as a proxy for q u of specimens normally cured under 28-day 23°C conditions. Moreover, lime and highway transportation industry associations prescribe a unique accelerated curing regime for all lime-stabilized soils (7-day, 41°C). This paper presents the results from a laboratory investigation of stress-strain-strength development of four lime-stabilized soils under 2-8 day 41°C accelerated curing and the 0-28 day 23°C normal curing regime. Specimens cured at 41°C reached q u values equivalent to 28-day 23°C q u after 1.8-5.9 days. Accordingly, 7-day 41°C curing overestimates 28-day normal cure q u by 13-260%. When combined with a detailed analysis of data available in the literature, the results illustrate that the prescription of a unique equivalent accelerated curing regime is oversimplified and can lead to significant overestimation of design q u .

This technical note assesses the widely accepted Thompson's equation used to approximate design resilient modulus (M r) for lime-stabilized soils from the results of unconfined compressive strength (q u) testing. There is limited evidence in the literature to support Thompson's equation relating q u and M r for lime-stabilized soils, and other studies have suggested that the relationship provides an excessively conservative approximation for design M r , specifically above q u 5 1,000 kPa. Laboratory M r and q u testing was performed on multiple specimens of three lime-stabilized soils. These data reveal that Thompson's equation provides a lower-bound estimate of M r from q u and that Little's recommended relationship provides a more reasonable match to the data. This study also illustrated a lack of a clear correlation between M r and q u .

U.S. Public Highway Construction Industry professionals are responsible for assessing and adopting new technology that can improve the cost and quality of roadways. This paper investigates features of the technology assessment and adoption process in the U.S. public highway construction industry that both facilitate and hinder responsible innovation. Often technological innovations are incongruent with current specifications, i.e., regulatory construction standards, whereby specification reform serves as a precursor to implementation. We examine this aspect of technology assessment and adoption through a novel application of Kingdon's theory of policy agenda setting to a highly technical state bureaucratic institution using a case study on Intelligent Compaction. Specification reform relating to Intelligent Compaction is occurring in nearly a quarter of U.S. states. Analysis of interviews with industry professionals revealed that institutional incentives for supporting innovations were not the main drivers for adoption, and there exists a conservative culture that inhibits change. Individuals that go against this grain by championing change do so based on their personal character, ideological affiliations and a perceived sense of social obligation, which coincides with the principles set forth in the responsible research and innovation literature. These individuals, whom we identify as Kingdon's policy entrepreneurs, appear to present themselves in four roles in this industry: explorer, pioneer, gatekeeper, and leader. Our findings indicate that alignment of these roles creates an environment conducive to responsible technology assessment and adoption, and therefore greater societal benefit. Ultimately, we hope this study will benefit U.S. Highway Construction Industry regulatory environments by enhancing identification of specification processes, key roles, and personal/ethical ideologies that may be conducive to fostering a culture of responsible innovation.

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