Statistical Variation in the Embodied Carbon of Concrete Mixtures

This study presents a refined calculation of the embodied carbon of concrete mixtures via life cycle assessment (LCA) with an explicit focus on three innovations. First, probability distributions that represent process-related variability in the embodied carbon of concrete are calculated using a variety of life cycle inventory data sources. Second, the traditional concrete LCA system boundary (i.e., cradle-to-gate) is expanded to incorporate and analyze estimates of in situ carbon sequestration via concrete carbonation. Third, we analyze the impact of different transportation scenarios on the utility of using fly ash to reduce the embodied carbon of concrete. We use these data to heuristically determine the breakeven transportation distance for fly ash via trucking to be 2655 km for domestic sources of fly ash. However, when fly ash is imported from international sources, reductions to embodied carbon attributed to fly ash replacement can be negligible. The calculated breakeven maritime shipping distance for fly ash equals 15,110 km&mdash;beyond which, the anticipated embodied carbon reductions due to fly ash use in concrete are compromised due to transportation. The advancements described herein enable improved scenario-based decision-making for understanding, quantifying, and reducing the embodied carbon of concrete mixtures. In addition, the results highlight the importance of accounting for international transportation of fly ash in LCAs, especially given that domestic sources of quality fly ash are expected to continue to decline and imports are expected to increase in many parts of the world over the next few decades. &nbsp;</p

A Comparison of Machine Learning Methods for Predicting the Compressive Strength of Field-Placed Concrete

This study evaluates the efficacy of machine learning (ML) methods to predict the compressive strength of field-placed concrete. We employ both field- and laboratory-obtained data to train and test ML models of increasing complexity to determine the best-performing model specific to field-placed concrete. The ability of ML models trained on laboratory data to predict the compressive strength of field-placed concrete is evaluated and compared to those models trained exclusively on field-acquired data. Results substantiate that the random forest ML model trained on field-acquired data exhibits the best performance for predicting the compressive strength of field-placed concrete; the RMSE, MAE, and R2 values were 730 psi, 530 psi, and 0.51, respectively. We also show that hybridization of field- and laboratory-acquired data for training ML models is a promising method for reducing common over-prediction issues encountered by laboratory-trained models that are used in isolation to predict the compressive strength of field-placed concrete.</p

Prediction model for hardened state properties of silica fume and fly ash based seawater concrete incorporating silicomanganese slag

Growing concrete consumption has gradually depleted conventional resources. This research incorporates silicomanganese (SiMn) slag, marine sand and seawater as alternative concreting materials. The use of SiMn slag to replace limestone as coarse aggregate enhances sustainability, though reducing strength and durability of concrete. This research aims to enhance the SiMn slag concrete by incorporating silica fume (SF) and fly ash (FA). The interaction of SF and FA on strength, durability and workability of concrete is investigated by statistically evaluating the experimental result. In this regard, the polynomial function prediction model is developed using the Response Surface Method (RSM) for the optimization of SF and FA contents. Analysis of variance (ANOVA) using p-value at significance level of 0.05 showed that the models were statistically significant and had marginal residual errors. All models had high fitness with R2 value ranging from 0.853 to 0.999. Adequate precision of models was above 4, indicating that the models had a low prediction error and were fit for optimization. Optimization indicated that a combination of 11.5% SF and 16.3% FA produced concrete that met the optimization criteria. Experimental validation showed that the highest prediction error was 3.4% for compressive strength, 3.2% for tensile strength, 4.9% for sorptivity and 18% for chloride permeability. The optimized concrete exhibited compact microstructure with good bonding between aggregate and cement paste. By using the established linear equation with SiMn slag concrete, the models also predicted the compressive strength of limestone concrete containing SF and FA with an error of between 0.9% and 5.4%

Le délainage à Mazamet

Mazamet, « centre mondial de délainage », vit encore d'une activité traditionnelle mais qui affronte aujourd'hui de redoutables problèmes d'adaptation. Les techniques industrielles et commerciales sont décrites dans une première partie, leurs problèmes dans la seconde partie, notamment ceux qui se posent à propos de la main-d'œuvre et des marchés. La conclusion insiste sur la possibilité d'une renaissance du délainage qui permettrait à Mazamet d'accéder au rôle de centre régional.Derousseau Bruno. Le délainage à Mazamet. In: Revue géographique des Pyrénées et du Sud-Ouest, tome 41, fascicule 3-4, 1970. pp. 347-362

La Coopérative agricole lauragaise

Derousseau Bruno. La Coopérative agricole lauragaise. In: Revue géographique des Pyrénées et du Sud-Ouest, tome 35, fascicule 2, 1964. pp. 214-220

Mieux considérer l'apprenant pour améliorer la formation dans deux associations d'alphabétisation au Cameroun

Ce mémoire rend compte d'une action menée au sein de deux associations d'alphabétisation du Cameroun, visant à améliorer la formation des adultes en difficulté à l'écrit en français. Ayant constaté une inadéquation entre les supports d'alphabétisation utilisés et le public des cours, nous avons proposé aux enseignants bénévoles une formation-action dont le but était de les aider à recentrer l'enseignement/apprentissage de l'écrit du français sur l'apprenant

Barriers to Nurse Practitioners in Rural Health Clinics in Kansas

The identification of barriers to the optimal use of the nurse practitioner (NP) within the Rural Health Clinics (RHC) in Kansas is essential in solidifying the role of the NP as a primary health care provider. As health care reform mandates the paradigm shift from treatment to prevention, more research regarding the optimal use of the NP is essential for several reasons. The nation is demanding accessibility of quality, cost-effective primary care for all. In spite of the research that has substantiated the quality and cost effectiveness of the care that NPs provide, barriers still exist that hinder their optimal utilization. This investigation was a quantitative descriptive study using a combination of Lewin\u27s Force Field Analysis and Margaret Newman\u27s Health Model to identify the existence of barriers and any variance in the views of the cohorts studied. The specific research questions were 1) What barriers to the use of nurse practitioners in Rural Health Clinics in Kansas exist? and 2) Are barriers to nurse practitioners in Rural Health Clinics in Kansas perceived the same way by administrators, physicians, and nurse practitioners who work in these Rural Health Clinics in Kansas? The subjects studied were nurse practitioners, physicians, and administrators who work in but are not confined to Rural Health Clinics in Kansas. There were 216 surveys distributed to a random sample and 92 cohorts responded from 61 different sites which is a 42.5% return. There were 27 nurse practitioners, 38 physicians, and 27 administrators who participated. The majority of the cohorts were in the age range of 40-50 years. The nurse practitioner cohort was female. The administrator and physician cohorts were 56% to 79% male. The majority of the Rural Health Clinics studied were Independent Based (75%) and physician owned (61%). Limitations of the study were: (a) population was limited to those cohorts who worked within the Rural Health Clinic system in Kansas, (b) the consumer was not surveyed, (c) the analysis was limited to three possible barriers, (d) all nurse practitioners surveyed were women which was a product of randomization, (e) only certified Rural Health Clinics were surveyed, and (f) the demographic area was limited to the state of Kansas. The findings of this study were that barriers to the use of the nurse practitioner do exist within the Rural Health Clinics setting and that the three cohorts studied have varying views regarding those barriers. Recommendations of the study are: (a) further education of the consumer, (b) further research of the knowledge base of the consumer, (c) further analysis of data obtained via the survey tool, (d) further studies of the female nurse practitioner versus the male nurse practitioner in the male dominated world of primary health care, and (e) further studies to clarify factors which affect the physicians views of supervising the nurse practitioner. In summary, this study identified that barriers do exist within the Rural Health Clinics in Kansas and that the cohorts studied have varying views. The Rural Health Clinics were established to enhance the use of the nurse practitioner. If there are barriers which exist within this system, it is indicative that barriers outside the system also exist. It is the desire of the investigator that more research will be initiated to improve the use of the nurse practitioner. It is also the opinion of this researcher that the nurse practitioner can play a major role in addressing the many issues of providing quality cost-effective primary health care for our nation