Abstract This study evaluated the performance of concrete and mortar made with three portland limestone (Type IL) cement sources, collected from Texas, Colorado, and Florida, in combination with two types of chemical admixtures including water reducing and air entraining admixtures, obtained from two manufacturers. The testing program included scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, air content, slump, finishability, compressive strength, drying shrinkage, and surface and bulk resistivity. The strength development in mixtures made with IL cement was lower than that of I/II cement. Compressive strength results were influenced by IL cement fineness, cement oxide composition, and dosage of chemical admixtures. Early-age drying shrinkage in samples containing IL cement was higher than in those with cement I/II during the first 24 h, highlighting the need for effective curing practices in field applications. Drying shrinkage results showed that samples containing IL cement had lower shrinkage after 24 h than mixtures with I/II cement. Surface and bulk resistivity tests revealed that concrete samples containing IL cement achieved up to 35% higher surface and bulk resistivity than concrete made with I/II cement, indicating improved durability potential.
Abstract This paper evaluates the behavior of ultrahigh performance concrete (UHPC) beams with transverse openings, a topic with practical implications that has not been studied thus far. Various parameters were examined; including the opening shape, location, and height; compressive strength of UHPC ( f c ′ ); internal steel reinforcement ratio; and using externally bonded fiber-reinforced polymer (FRP) sheets to reinforce the opening region. A robust nonlinear finite-element model was validated with two different experimental sets from the literature and used in a comprehensive parametric study totaling 104 specimens. The results show that, while openings in general inversely affect the UHPC beam strength and stiffness, the impact corresponds with the opening’s shape, height, and reinforcement ratio. Smaller openings near the supports have much less impact than those with larger sizes placed in the middle part. Stress concentrations are observed around the opening’s edges, causing higher stresses in the surrounding regions. Applying FRP sheets resulted in various strength and stiffness recoveries, dependent on the composite length. Increasing f c ′ increased the beam’s peak load, which can be a design option to mitigate the effects of openings. Numerous results are presented in the manuscript offering guidance for proper selection and placement of openings in field applications.
Abstract Agriculture depletes soil organic carbon (SOC), partly due to the exclusion of deep‐rooted perennials. Reintroducing deep‐rooted perennials to cultivated land may help to mitigate SOC loss. We quantified the effect of deep roots on SOC by comparing 8 to 30 year‐old stands of switchgrass (Panicum virgatum L.) with paired annual row crop fields at 12 sites across the central and eastern USA. We hypothesized that switchgrass would store more root C and SOC than neighboring shallow‐rooted annual crops, and that these effects would extend deeper than 30 cm. We also evaluated whether switchgrass stimulates decomposition of SOC at depth using radiocarbon (14C). Finally, we explored whether the effect of switchgrass on SOC is moderated by soil chemical and physical properties. While the effect of switchgrass on SOC in the surface 100 cm was positive at most sites, the average effect was not statistically significant (difference in SOC = 0.6 kg C m−2 [95% CI −0.8 to +1.9 kg C m−2]). By contrast, we found that root C was consistently more abundant under switchgrass, yielding an estimated additional 0.6 kg C m−2 in the surface 100 cm of soil [95% CI +0.5 to +0.7 kg C m−2]. 14C measurements suggested that root C inputs were adding to existing SOC without stimulating decomposition. The effect of switchgrass on belowground C was not strongly related to any of the soil properties that we evaluated. Our observations show that root C can contribute substantially to belowground C stocks when deep‐rooted perennials replace shallow‐rooted crops.
Sensemaking plays a critical role in social media, which features ambiguous, equivocal, and dynamic information, views, and opinions. While existing research has focused on sensemaking with respect to text entries related to extreme events, we examine sensemaking with respect to video content on social media. Drawing on sensemaking theories, we investigate the relationships between video features and sensemaking activities. Specifically, we analyze how information control, cue, and noise in YouTube videos affect sensemaking activities on YouTube and Reddit. Our findings reveal both similarities and differences in how these factors relate to sensemaking activities across the two platforms. This research enriches the current literature on social media sensemaking and provides insights for designing videos that better facilitate sensemaking activities and enhance user experiences.
