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  1. Free, publicly-accessible full text available August 1, 2025
  2. The inclusion of rubber in concrete has been suggested and used in recent research. However, the reason for the inclusion of rubber into concrete is typically the need to offset the carbon footprint of concrete and other environmental concerns. The research presented here indicates that the inclusion of rubber into concrete allows for the concrete to accept fasteners and withstand withdrawal, or pullout, of the fasteners, similar to the function of wood. We refer to this as making the concrete “nailable”, in that the concrete can be nailed together either by hand or with tools designed to be used with wood. While other methods have been used to make concrete nailable, this method is novel as no known research exists indicating that there exists a rubber concrete mix that provides similar withdrawal strength as wood. Testing indicates that the concrete can be produced at a low cost due to the inclusion of the low-cost rubber infill with reinforcement wire. The result is a reinforced concrete with an allowable load that is 13% greater than in spruce and a withdrawal force up to 25% greater than the maximum in spruce. The intended function of this material is replacement of treated lumber. The proposed rubber concrete, which is a reinforced concrete, is anticipated to have a service life of 50–100 years, while treated lumber decks in the Southeastern United States have been surveyed to have an average life of only 10 years due to environmental degradation. This leads us to conclude that if a deck were to be constructed of this nailable rubber concrete, it would last approximately five times longer in a temperate environment, such as the Southeastern United States. This improvement can be provided at a relatively low cost while providing an alternative that both prevents the use of arsenic- and copper-containing compounds used in treated lumber and provides an additional recycling method for tires.

     
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  3. Glass-reinforced composite columns (GRCCs) may provide an economical alternative to conventional construction materials due to the superior cost to strength provided by bulk glass. Prior to this study, no GRCCs had been physically tested, having previously relied on simulation to predict the behavior of the columns. This study utilizes polyurethane resin bonds in place of sizing agents for adherence between materials, a key requirement for the development of the structural system of the columns. The unreinforced control column failed at a load of 11.2 kN while the maximum GRCC load was 30.8 kN. This indicates that glass can be loaded to 123 MPa before the onset of delamination failure of the GRCCs. Maximum shear stress of 53 MPa was reached, exceeding the 11 MPa required for practical GRCCs. Buckling of the columns occurred at 30.8 kN, below the theoretical maximum of 64.4 kN. Through gradual delamination, the column slowly transferred to an unbonded condition, causing buckling failure. Delamination is unlikely to occur in practical GRCCs due to the lower required shear strengths.

     
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  4. The metacognitive strategies of planning, monitoring, and evaluating can be promoted through systematic reflection to drive self-directed, lifelong learning. This article reports on a three-year study on systematic written reflection within an undergraduate Fluid Mechanics course to promote planning, monitoring, and evaluation. Students were prompted weekly to reflect on their in-class problem-solving, classroom and exam preparation, performance, behaviors, and learning in a flipped classroom at a large southeastern U.S. university. In addition, they received intentional instruction on how to plan, monitor, and evaluate their problem-solving during class. To enable a comparative assessment, a flipped classroom without these interventions was also implemented as a non-experimental cohort. The cohorts were compared using a final exam, concept inventory, and the Metacognitive Activities Inventory (MCAI). The MCAI indicated a significantly higher positive change (pre- to post-course) in self-regulatory behavior for the experimental cohort ( p = 0.037). The weekly reflections were studied using an inductive content analysis to assess students’ self-regulatory behaviors. They were also used to investigate statistical associations between reflection content and course outcomes. This revealed that academic self-discipline via planning, monitoring one's work, or being careful and diligent may be as aligned with course performance in STEM as is practice with the problem-solving itself. The effects for the final exam in the experimental cohort were positive overall as well as statistically or practically significant for various demographic strata. These results provided evidence for the potential enhancement of course performance with metacognition support. A positive shift in students’ perspectives regarding the value of the reflection questions was observed throughout the study. Therefore, as an implementation guide for other educators, the reflection questions and any changes made in posing them to students are discussed chronologically. Overall, the study points to the desirability of providing metacognition support in a STEM course.

     
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  5. When students repeatedly reflect, it can enhance their metacognitive abilities, including self-regulatory skills of planning, monitoring, and evaluating. In a fluid mechanics course for undergraduates at a large southeastern U.S. university, in-class problem solving in a flipped classroom was coupled with intentional metacognitive skills instruction and repeated reflection to enhance metacognition. The weekly reflective responses were coded by two analysts to identify the recurring themes and uncover evidence of the development and/or reinforcement of self-regulating behaviors for academic management. To enable a comparison, a flipped classroom without the metacognitive instruction and repeated reflection was also implemented (i.e., non-intervention group). The two cohorts completed identical final exams. Based on our preliminary analysis with year one data, a statistically and practically-significant difference between the two cohorts was found with the free-response scores on the final exam in favor of the intervention cohort that had received the metacognitive support ( p < 0.0005; Cohen's d = 0.72). Also, the Metacognitive Activities Inventory (MCAI) indicated a significantly-higher positive change in self-regulatory behavior for the intervention cohort ( p = 0.001; d = 0.50). Focus groups were conducted to gather students’ perspectives on the reflective activity, with differences found by demographic group. In addition, a significantly higher proportion of females (versus males) viewed the reflections in a positive manner ( p = 0.05). Significant associations between themes in the weekly reflections and direct knowledge measures were also uncovered. This included a positive relationship between academic self-management (i.e., diligence and carefulness) and exam performance. Overall, our preliminary results point to a desirable impact of metacognitive instruction and repeated reflection on knowledge outcomes, metacognitive skills, and self-regulatory behaviors.

     
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