Unlocking the role of recycled aggregates in the performance enhancement and CO2 capture of reactive magnesia cement formulations

The use of recycled aggregates (RCAs) could further enhance the sustainability of reactive magnesia cement (RMC) formulations, but the performances of RMC-RCA are still unknown to researchers. Therefore, in this study, the strength development of CO 2-cured RMC-RCA was explored for the first time, and the strength variation among groups was further interpreted by microstructural analyses. The initial results show that compared with samples with natural aggregates (NAs), a 28 d strength boost (i.e., 37 vs. 15 MPa) in RMC-RCA can be observed. The strength improved in RMC-RCA could be related to its refined microstructures, ITZs and larger carbonation depths, which resulted from the easiness of CO 2 penetration within samples. Then the presence of porous ITZs in RCA contributes to better CO 2 diffusion, as described in the proposed revised CO 2 diffusion model. Overall, while enabling a pronounced CO 2 capture potential of RMC concrete, this preliminary study could pave the path for the upcycling of RCAs in RMC concrete on a large scale.</p

Overcoming acculturation: physical education recruits' experiences of an alternative pedagogical approach to games teaching

© 2015 Association for Physical Education Background: Physical education teacher education (PETE) programmes have been identified as a critical platform to encourage the exploration of alternative teaching approaches by pre-service teachers. However, the socio-cultural constraint of acculturation or past physical education and sporting experiences results in the maintenance of the status quo of a teacher-driven, reproductive paradigm. Previous studies have reported successfully overcoming the powerful influence of acculturation, resulting in a change in PETE students' custodial teaching beliefs and receptiveness to alternative teaching approaches. However, to date, limited information has been reported about how PETE students' acculturation shaped their receptiveness to an alternative teaching approach. This is particularly the case for PETE recruits identified in the literature as most resistant to change. Purpose: To explore the features and experiences of an alternative games teaching approach that appealed to PETE recruits identified as most resistant to change, requiring a specific sample of PETE recruits with strong, custodial, traditional physical education teaching beliefs, and whom are high-achieving sporting products of this traditional culture. The alternative teaching approach explored in this study is the constraints-led approach (CLA), which is similar operationally to Teaching Games for Understanding, but distinguished by a neurobiological theoretical framework (nonlinear pedagogy) that informs learning design. Participants and setting: A purposive sample of 10 Australian PETE students was recruited for the study. All participants initially had strong, custodial, traditional physical education teaching beliefs, and were successful sporting products of this teaching approach. After experiencing the CLA as learners during a games unit, participants demonstrated receptiveness to the alternative pedagogy. Data collection and analysis: Semi-structured interviews and written reflections were sources of data collection. Each participant was interviewed separately, once prior to participation in the games unit to explore their positive physical education experiences, and then again after participation to explore the specific games unit learning experiences that influenced their receptiveness to the alternative pedagogy. Participants completed written reflections about their personal experiences after selected practical sessions. Data were qualitatively analysed using grounded theory. Findings: Thorough examination of the data resulted in establishment of two prominent themes related to the appeal of the CLA for the participants: (i) psychomotor (effective in developing skill) and (ii) inclusivity (included students of varying skill level). The efficacy of the CLA in skill development was clearly an important mediator of receptiveness for highly successful products of a traditional culture. This significant finding could be explained by three key factors: the acculturation of the participants, the motor learning theory underpinning the alternative pedagogy and the unit learning design and delivery. The inclusive nature of the CLA provided a solution to the problem of exclusion, which also made the approach attractive to participants. Conclusions: PETE educators could consider these findings when introducing an alternative pedagogy aimed at challenging PETE recruits' custodial, traditional teaching beliefs. To mediate receptiveness, it is important that the learning theory underpinning the alternative approach is operationalised in a research-informed pedagogical learning design that facilitates students' perceptions of the effectiveness of the approach through experiencing and or observing it working

Increased masticatory activity and quality of life in elderly persons with dementia-a longitudinal matched cluster randomized single-blind multicenter intervention study.

Background: Worldwide, millions of people are suffering from dementia and this number is rising. An index of quality of life (QoL) can describe the impact a disease or treatment has on a person's wellbeing. QoL comprises many variables, including physical health and function, and mental health and function. QoL is related to masticatory ability and physical activity. Animal studies show that disruption of mastication due to loss of teeth or a soft diet leads to memory loss and learning problems. Since these are common complaints in dementia, it is hypothesized that improvement of masticatory function and normalization of diet consistency can increase QoL in elderly persons suffering from dementia. Therefore, the goal of the present study is to examine whether an increase in masticatory activity, achieved by increased food consistency and enhancement of masticatory function through improved oral health care has a positive effect on QoL, including cognition, mood, activities of daily living (ADL), and circadian rhythm in elderly persons with dementia.Methods and design: The described study is a prospective longitudinal matched cluster randomized single-blind multicenter study. Participants are elderly persons living in the Netherlands, suffering from dementia and receiving psychogeriatric care. An intervention group will receive improved oral health care and a diet of increased consistency. A control group receives care as usual. Participants will be assessed four times; outcome variables besides QoL are cognition, mood, independence, rest-activity rhythm, blood pressure, and masticatory function.Discussion: This research protocol investigates the effect of an intervention executed by daily caregivers. The intervention will increase masticatory activity, which is achieved by three different actions, (providing oral health care, increasing food consistency, or a combination of both). There is a certain amount of variety in the nature of the interventions due to local differences in nursing homes. This might be a scientific weakness in the study design; however, a practical implementation of any findings will be subject to the same factors, making this study design clinically relevant.Trial registration: NTR1561. © 2013 Weijenberg et al.; licensee BioMed Central Ltd

High attaining students, marketisation and the absence of care: everyday experiences in an urban academy

This article draws on the work of Nel Noddings to suggest that the current neoliberal, marketised system of education is eroding caring relationships in schools. Data are drawn from a small-scale qualitative study of an ethnically diverse group of high attaining sixth form students from a successful urban academy. Based on this data, we argue that two fundamental aspects of care, students’ relationships with their teachers and an attention to their personal and social concerns, were neglected because of the overriding focus on examination success to maintain the school’s position in the education marketplace. The article offers detailed evidence from the students’ perspective to support the claim that the marketisation of the education system leads to students being valued only in as far as they bring value to the school. It also suggests that care is one of the main casualties in such a system

Using video-reflexive ethnography and simulation-based education to explore patient management and error recognition by pre-registration physiotherapists

Background: Upon graduation, physiotherapists are required to manage clinical caseloads involving deteriorating patients with complex conditions. In particular, emergency on-call physiotherapists are required to provide respiratory/ cardio-respiratory/cardiothoracic physiotherapy, out of normal working hours, without senior physiotherapist support. To optimise patient safety, physiotherapists are required to function within complex clinical environments, drawing on their knowledge and skills (technical and non-technical), maintaining situational awareness and filtering unwanted stimuli from the environment. Prior to this study, the extent to which final-year physiotherapy students were able to manage an acutely deteriorating patient in a simulation context and recognise errors in their own practice was unknown. Methods: A focused video-reflexive ethnography study was undertaken to explore behaviours, error recognition abilities and personal experiences of 21 final-year (pre-registration) physiotherapy students from one higher education institution. Social constructivism and complexity theoretical perspectives informed the methodological design of the study. Video and thematic analysis of 12 simulation scenarios and video-reflexive interviews were undertaken. Results: Participants worked within the professional standards of physiotherapy practice expected of entry-level physiotherapists. Students reflected appropriate responses to their own and others’ actions in the midst of uncertainty of the situation and physiological disturbances that unfolded during the scenario. However, they demonstrated a limited independent ability to recognise errors. Latent errors, active failures, error-producing factors and a series of effective defences to mitigate errors were identified through video analysis. Perceived influential factors affecting student performance within the scenario were attributed to aspects of academic and placement learning and the completion of a voluntary acute illness management course. The perceived value of the simulation scenario was enhanced by the opportunity to review their own simulation video with realism afforded by the scenario design. Conclusions: This study presents a unique insight into the experiences, skills, attitudes, behaviours and error recognition abilities of pre-registration physiotherapy students managing an acutely deteriorating patient in a simulation context. Findings of this research provide valuable insights to inform future research regarding physiotherapy practice, integration of educational methods to augment patient safety awareness and participant-led innovations in safe healthcare practice. Keywords: Error recognition, Deterioration, Physiotherapy, Simulation-based education, Video-reflexive ethnograph

Influence of supplementary cementitious materials on the performance and environmental impacts of reactive magnesia cement concrete

This paper investigated the performance and environmental impacts of reactive magnesia cement (RMC)-based formulations containing pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS). Concrete samples, whose binder component was composed of RMC with 0–50% PFA and GGBS replacement were subjected to carbonation curing for up to 28 days. The performance of each sample was analyzed and compared to corresponding Portland cement (PC)-based samples via porosity, water sorptivity, compressive strength and thermal conductivity measurements. The performance results were supported with the assessment of the environmental impact of each sample throughout their production and utilization phases. Samples in which 50% of the binder component was replaced by PFA indicated the highest strength development, reaching strengths as high as 60 MPa at 28 days, which were 33% higher than those of the corresponding RMC control sample. The advantageous strength gain demonstrated by RMC-PFA samples was associated with a reduction in sample porosity due to the filler effect of PFA as well as the formation of strength providing phases through the hydration and carbonation reactions. The use of both PFA and GGBS decreased the environmental impacts of RMC formulations, which was reflected as lower CO2 emissions, as well as reduced damage on human health and eco-system quality when compared to RMC and PC samples. The environmental efficiency calculations involving a combination of the net CO2 emissions and mechanical performance of each sample revealed the benefits of supplementary cementitious materials within RMC formulations

Comparative life cycle assessment of reactive MgO and Portland cement production

Reactive magnesia (MgO) cements are proposed as a potentially sustainable binder due to their lower production temperatures (∼800 vs. 1450 °C) than Portland cement (PC) and ability to fully carbonate and gain strength during setting. Reactive MgO is mainly produced via the calcination of magnesite. Environmental implications of reactive MgO production must be analyzed before any final conclusions can be made regarding their contribution to the sustainability of the cement industry. This study evaluates the environmental impacts of reactive MgO production and provides a comparison with PC production using a life-cycle assessment (LCA) approach. The advantages of MgO production with respect to radiation, ozone layer, eco-toxicity, acidification/eutrophication, minerals and fossil fuels outweigh the disadvantages when compared to PC production. MgO has a lower impact on the overall ecosystem quality and resources than PC, but poses a larger damage to human health due to the high coal usage by most plants. The decomposition of magnesite releases a higher amount of CO2 than limestone (∼1.1 vs. 0.78–0.83 t/t), creating a higher climate change score for MgO despite its lower production temperatures. However, when the carbonation capability of MgO cements is considered, their net CO2 emissions are ∼73% lower than PC. The introduction of a strength ratio modification to MgO production results in ∼13% and ∼32% lower CO2 intensity and damage impact on human health when compared to PC production, respectively. The influence of energy type and amount on different impact and damage categories associated with MgO production was revealed by scenario modelling. The quantity of raw materials had a negligible effect on the overall environmental impact of reactive MgO production, whereas increasing the emissions led to an increase in climate change. Energy was identified as the key parameter with the highest influence on the environmental burdens of reactive MgO production. Results indicate that the use of alternative fuels could further improve the overall sustainability of reactive MgO cement production

Effect of air entrainment on the performance of reactive MgO and PC mixes

This study investigated the influence of air-entraining agents (AEA) on the performance and microstructure of reactive MgO cement (RMC) samples in comparison with Portland cement (PC) samples under different water contents and curing conditions. Porosity, density, workability, strength, pH and thermal conductivity measurements were supported with XRD, TGA/DSC and SEM analyses. Performance of RMC samples depended on the dense formation of carbonate phases such as nesquehonite and hydromagnesite, whereas PC samples gained strength by hydration. Introduction of AEA reduced early strength due to increased air contents. This was compensated by increased CO2 penetration, carbonation and strength gain in longer periods