The purpose of this study is to investigate news activators in the preparation of alkali-activated materials (AAMs) alternative to Portland cements by reusing waste glass. Alkali-activated blast ...furnace slag (AAS) constitutes an alternative to Portland cement due to high energy and environmental pollution associated with industrial Portland cement. Moreover, alkali activated materials offer a series of higher properties than ordinary Portland cement (OPC), such as better strength and durability behaviour. However, the rheology of these materials has been much less intensely researched.
The present study aimed to study the effect of waste glass as activator and as replacement of blast furnace slag on the rheological behaviour of AAS pastes, with a comparison between the rheological parameters and fluidity of these pastes to the same parameters in standard cements (CEM I and CEM III/B).
The findings show that AAS paste behaviour of rheology when the activator was a commercial waterglass solution or NaOH/Na2CO3 with waste glass was similar, fit the Herschel-Bulkley model. The formation of primary C-S-H gel in both cases were confirmed. However, the rheological behaviour in standard cements fit the Bingham model. The use of the waste glass may be feasible from a rheological point of view in pastes can be used.
El propósito de este estudio es investigar nuevos activadores alcalinos a través de la reutilización de residuos vítreos en la preparación de materiales activados alcalinamente alternativos al cemento Portland (OPC). Las escorias activadas alcalinamente (AAS) son una alternativa al cemento Portland debido a la alta demanda energética y medioambiental asociada en la producción de este. Además, estos materiales activados alcalinamente ofrecen mejores propiedades que el cemento Portland, como un buen comportamiento mecánico y durable. Sin embargo, el comportamiento reológico de estos materiales ha sido poco investigado.
El presente estudio tiene como objetivo estudiar el efecto del residuo vítreo como activador y como sustitución de la escoria en el comportamiento reológico de las pastas, con una comparación entre los parámetros reológicos y de fluidez de estas pastas frente a los mismos en los cementos normalizados (CEM I and CEM III/B).
Los resultados reológicos de las pastas de escoria activada alcalinamente cuando los activadores fueron una disolución comercial de waterglass y NaOH/Na2CO3 con el residuo vítreo presentaron un comportamiento muy similar, describiendo un modelo Herschel-Bulkley, en donde se confirmó la formación de un gel C-S-H primario en ambos casos. Sin embargo, el comportamiento reológico en los cementos normalizados describe un modelo Bingham. El uso de un residuo vítreo puede ser factible desde un punto de vista reológico en las pastas de escoria activadas alcalinamente.
Environmental issues are increasingly recognised as a significant concern for tourism industries worldwide. In this exploratory work, a model of environmental practices adoption and its impact on ...independent hotels is developed. Two different destinations are proposed and analysed: the mature market of Madrid in Spain and the emerging destinations of Santiago and Valparaiso in Chile. To test the model, a qualitative method based on case studies of 24 hotels—12 hotels for each country—was used. The findings show that environmental practices are implemented in both destinations and demonstrate the diverse impacts of this implementation, primarily in the financial and operational spheres. Differences are observed in the two countries regarding the proposed model, mainly in terms of barriers to implementing environmental practices, products used and processes related to clients and suppliers' responsibility. Therefore, this research implies that the hotels analysed are adopting an environmental management approach, although in different ways. The added value of this research is that it sheds light on the vision of sustainability in emerging and mature destinations and offers practical suggestions for hotel management regarding the implementation of various environmental practices and new environmental practices in hotel management.
•Environmental practices in hotels located at two destinations of different stages of maturity are measured.•Based on a proposed model, a qualitative approach was developed based on 24 hotels.•Results show substantive differences between the two destinations.
Overtourism spoils the good economic and social results produced by the tourism sector, causing reductions in the quality of service of the tourist destination and rejection by the local population. ...Previous literature has suggested that social networks and new electronic channels could be accelerators of the process of overcrowding destinations; however, this link has not been established. For this reason, in this exploratory study, the influence of social networks on overtourism is analysed using Barcelona as a base, as Barcelona is a massively popular destination in the country that is second in the world in reception of tourists to Spain. This study is also focused on Chinese tourism, which brings large numbers of tourists and presents great economic potential. Two types of study have been used: big data techniques applied to social media with sentimental analysis, and analysis of travel packages offered in China to travel to Spain. Relevant results are obtained to understand the influence of social networks on the travel behaviour of tourists, possible contributions to overtourism, and recommendations for the management of tourism.
Car sharing services have expanded in order to meet the new necessities of mobility worldwide in an innovative way. Before the COVID-19 pandemic, car sharing was a very popular mode of transportation ...among young adults in big cities. However, during this ongoing pandemic and with public transportation considered a super-spreading transmitter, the usage of car sharing is unclear. Therefore, the aim of this study, which is explorative in nature, is to investigate the usage, advantages, drivers, and barriers to car sharing during this ongoing pandemic era. To this end, 66 interviews were conducted among users of car sharing during the COVID-19 pandemic. The findings provide key information for the planning of car sharing operations and public transportation in the context of avoiding COVID-19 infection and respecting the recommendations of local governments. In addition, new emerging profiles of car sharing users in the ongoing pandemic are identified. This research provides relevant insights for both business practice and policy makers.
Diffusion of quality standards in the hospitality sector del Mar Alonso-Almeida, María; Marimon, Frederic; Bernardo, Merce
International journal of operations & production management,
01/2013, Letnik:
33, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Purpose - The aim of this study is to compare the diffusion of certifications under two quality management systems (QMSs) in the tourism sector in Spain: the generic ISO 9001 international standard; ...and the Spanish industry-specific "Q" standard.Design methodology approach - The study pursues this objective by comparing the logistic curves of dissemination of certifications under the two standards using data obtained from official sources. This analysis is complemented with qualitative data from several case studies of Spanish hotels and restaurants.Findings - The results show that the two standards are at different stages of diffusion: certification under the Spanish "Q" standard is increasing, while the ISO 9001 international standard seems to have reached saturation point, despite the fact that a lower number of certifications have been registered under ISO 9001 than under the "Q" standard.Originality value - The main contribution of this study is that it is one of the first to analyse the dissemination of quality standards in a specific sector. The findings are thus of considerable importance in extending knowledge of quality management in the tourism sector.
Purpose
Adopting Ajzen’s theory of planned behaviour theoretical framework, this paper aims to explore repurchase intentions among short-term rental users and changes in determinants of repurchase ...intention in the context of the COVID-19 pandemic.
Design/methodology/approach
Data for the research was collected via a cross-country quantitative survey (N = 1,433) in five European countries: Croatia, Italy, Spain, Turkey and the UK during 2020. Trust, perceived value, authenticity and perceived risk were incorporated into the structural equation model as part of an integrated analysis of antecedents of repurchase intention.
Findings
Perceived value and authenticity are the key drivers of a positive attitude to repurchase of short-term rentals even after the pandemic. The pandemic modified the role of perceived risk in determining attitude towards short-term rentals as perceived risks could negatively affect attitude and repurchase intention after COVID-19. Trust in the platform and the host became a significant determinant of repurchase intentions after the spread of COVID-19.
Research limitations/implications
The analysis has shown the link between attitude, subjective norms, perceived behavioural control and repurchase intention, and has thus demonstrated a successful application of the theory of planned behaviour to short-term rental users.
Originality/value
The results of this study suggest a possible reconceptualisation of repurchase determinants due to the pandemic. The study offers a timely contribution to the research on the impact of the pandemic on the determinants of tourists’ repurchase intentions.
In the last decade, the sharing economy has emerged as a business model that improves the use of goods, uses fewer resources than traditional markets, increases social interactions and promotes more ...responsible and environmentally friendly consumption. This has led various authors to propose that the sharing economy could be a business model that will change consumers’ relationship to objects and the materialistic lifestyle. This exploratory research is, to the best of our knowledge, the first to specifically identify a new consumer materialism with the sharing economy. To this end, a survey was conducted among 384 participants in the sharing economy, identifying not only the drivers of the new materialism but also their impact on consumption.
Our conclusions show that we are currently experiencing a new materialism in which the main elements of traditional materialism—property and the accumulation of goods and the happiness derived from the accumulation of goods and their exhibition as a status symbol—are losing importance. Thus, materialism is evolving from a mere static accumulation of goods towards a hybrid model in which property and the enjoyment of goods coexist with the enjoyment of experiences, which are becoming increasingly more important. Last, participation in the sharing economy drives this new materialism through its contribution to a greater awareness of consumption. In other words, the consumer has a greater consumption awareness.
This paper proposes theoretical foundations to conceptualize the new materialism and a new materialist consumer profile that represents a break from the traditional conception, provides evidence on the dynamics of the feedback and empowerment of the sharing economy, and finally contributes by shedding light on its impact because the dynamics and impact of the sharing economy are more complex than they initially seem and thus it is necessary to analyse different angles and concepts.
The current business market is characterized by rapid and continuous changes. Companies should adapt to new situations to guarantee sustainable development. Managers need to have capabilities to ...understand the new environment’s requirements. Managers’ individual dynamic capabilities (IDC) help them face these unpredictable changes in the market. However, few authors have analysed individual dynamic capabilities to ensure business sustainability. This study aims to shed light on the relationship between a manager’s IDC and business sustainability from a gender perspective. A survey of 339 managers was conducted, and Structural Equation Modelling (SEM) was applied to study the impact of the relationship. The results show that managers’ individual dynamic capabilities help them detect changes in the market earlier and promote a greater social and environmental commitment from those managers. In addition, significant differences in the environmental and social commitment between men and women were found. Therefore, this paper first provides advice for developing business sustainability to provide an advantage for organizations. Second, individual dynamic managerial capabilities appear to be important for promoting sustainability. Finally, another step in the construction of gender and sustainability is provided. Thus, this paper provides useful empirical evidence for managerial practice from a strategic management viewpoint.
•Individual dynamic capabilities have an impact on their sustainable commitment.•Individual dynamic capabilities appear to be a driver for sustainable development.•Individual dynamic capabilities are not gender neutral regarding sustainability.
To analyse the characteristics and predictors of death in hospitalized patients with coronavirus disease 2019 (COVID-19) in Spain.
A retrospective observational study was performed of the first ...consecutive patients hospitalized with COVID-19 confirmed by real-time PCR assay in 127 Spanish centres until 17 March 2020. The follow-up censoring date was 17 April 2020. We collected demographic, clinical, laboratory, treatment and complications data. The primary endpoint was all-cause mortality. Univariable and multivariable Cox regression analyses were performed to identify factors associated with death.
Of the 4035 patients, male subjects accounted for 2433 (61.0%) of 3987, the median age was 70 years and 2539 (73.8%) of 3439 had one or more comorbidity. The most common symptoms were a history of fever, cough, malaise and dyspnoea. During hospitalization, 1255 (31.5%) of 3979 patients developed acute respiratory distress syndrome, 736 (18.5%) of 3988 were admitted to intensive care units and 619 (15.5%) of 3992 underwent mechanical ventilation. Virus- or host-targeted medications included lopinavir/ritonavir (2820/4005, 70.4%), hydroxychloroquine (2618/3995, 65.5%), interferon beta (1153/3950, 29.2%), corticosteroids (1109/3965, 28.0%) and tocilizumab (373/3951, 9.4%). Overall, 1131 (28%) of 4035 patients died. Mortality increased with age (85.6% occurring in older than 65 years). Seventeen factors were independently associated with an increased hazard of death, the strongest among them including advanced age, liver cirrhosis, low age-adjusted oxygen saturation, higher concentrations of C-reactive protein and lower estimated glomerular filtration rate.
Our findings provide comprehensive information about characteristics and complications of severe COVID-19, and may help clinicians identify patients at a higher risk of death.
Display omitted
In calcium aluminate cements (CAC), it is recommended to work with low water/cement ratios (for example using superplasticizers admixtures) to avoid the negative effects of metastable hexagonal ...hydrate conversion to stable cubic ones. The present work studies the compatibility between CAC and three polycarboxylate ether (PCE) admixtures with different structures. The C/E ratio of PCE admixtures was less important to the adsorption values in CAC suspensions than those of Portland-based binder (OPC). The more positive zeta potential in the CAC pastes may be the reason why these admixtures (regardless of their C/E ratio) adsorb onto cement particles with a different conformation than observed in OPC pastes. The presence of PCE admixtures decreases yield stress of CAC pastes at a lower dosage than that needed for OPC pastes. However, after 15 min CAC pastes with PCE admixtures lose their fluidity, an indication of the scant compatibility between these materials.
PDF
