21 research outputs found
Influence of Calcined Clay on Workability of Mortars with Low-carbon Cement
The second-largest industrial global emitter of CO2 (Carbon dioxide) is the cement sector. The technology roadmap of low carbon transition for cement industries includes the introduction of calcined clay (CC) as supplementary cementitious material. A new type of alternative binder, called Limestone Calcined Clay Cement (LC3), was recently proposed. This cement can reduce CO2 emissions of cement production by up to 40% and it is prepared using limestone (LS) and clay which are globally available. Many scientific studies aimed to investigate the hydration of LC3 to understand the contribution of CC to the development of the compressive strength. However, recent studies showed that other cement properties, like workability and water demand, are highly impacted by calcined clay. Despite some papers state that an increase in superplasticizer (SP) dosage compensate this effect, such concrete is usually sticky, and hard to handle and deal with. In this sense, a proper understanding of the mechanisms regulating rheology of LC3 is needed. The objective of this study is to analyze workability of CC-based cement pastes and mortar, specifically investigating the role of free water in particle suspensions. Preliminary results show that CC highly influences workability of mortars and pastes. The flow table test results highlight a need to increase SP dosage to achieve target workability with CC cements. Differential scanning calorimetry (DSC) and 1 H time domain-nuclear magnetic resonance (TD-NMR) results clarify that the capillary unbound water is rapidly consumed by CC, being thus unavailable to fluidify cement pastes. This multi-method approach provides a further step in understanding CC impact on workability of mortars with low-carbon cement and opens new ways to understand paste, mortar, and concrete workability
Negative attitudes related to violence against women: gender and ethnic differences among youth living in Serbia
OBJECTIVES: This study aimed to identify to what extent negative attitudes towards intimate partner violence against women are present among young women and men living in Serbia, in Roma and non-Roma settlements. METHODS: We used the data from the 2010 Multiple Indicator Cluster Survey conducted in Serbia, for the respondents who were 15-24 years old. Regression analyses were used to examine the association between judgmental attitudes, socio-demographic factors and life satisfaction. RESULTS: In Roma settlements, 34.8% of men and 23.6% of women believed that under certain circumstances men are justified to be violent towards wives, while among non-Roma it was 5.6 and 4.0%, respectively. These negative attitudes were significantly associated with lower educational level, lower socio-economic status and being married. In multivariate model, in both Roma and non-Roma population women who were not married were less judgmental, while the richest Roma men were least judgmental (OR 0.40, 95% CI 0.18-0.87). CONCLUSIONS: Violence prevention activities have to be focused on promoting gender equality among youth in vulnerable population groups such as Roma, especially through social support, strengthening their education and employment
The burden of breast, cervical, and colon and rectum cancer in the Balkan countries, 1990–2019 and forecast to 2030.
Background
Despite effective prevention and control strategies, in countries of the Balkan region, cancers are the second leading cause of mortality, closely following circulatory system diseases.
Objective
To describe trends in the burden of breast, cervical, and colon and rectum cancer in the Balkan region and per country between 1990 and 2019, including a forecast to 2030.
Methods
We described the 2019 Global Burden of Disease (GBD) estimates for breast, cervical, and colon and rectum cancers in eleven Balkan countries over the period 1990–2019, including incidence, years lived with disability (YLD), years of life lost (YLL), and disability-adjusted life years (DALYs) rates per 100,000 population and accompanied 95% uncertainty interval. With the Autoregressive Integrated Moving Average, we forecasted these rates per country up to 2030.
Results
In the Balkan region, the highest incidence and DALYs rates in the study period were for colon and rectum, and breast cancers. Over the study period, the DALYs rates for breast cancer per 100,000 population were the highest in Serbia (reaching 670.84 in 2019) but the lowest in Albania (reaching 271.24 in 2019). In 2019, the highest incidence of breast cancer (85 /100,000) and highest YLD rate (64 /100,000) were observed in Greece. Romania had the highest incidence rates, YLD rates, DALY rates, and YLL rates of cervical cancer, with respective 20.59%, 23.39% 4.00%, and 3.47% increases for the 1990/2019 period, and the highest forecasted burden for cervical cancer in 2030. The highest incidence rates, YLD rates and DALY rates of colon and rectum cancers were continuously recorded in Croatia (an increase of 130.75%, 48.23%, and 63.28%, respectively), while the highest YLL rates were in Bulgaria (an increase of 63.85%). The YLL rates due to colon and rectum cancers are forecasted to progress by 2030 in all Balkan countries.
Conclusion
As most of the DALYs burden for breast, cervical, and colon and rectum cancer is due to premature mortality, the numerous country-specific barriers to cancer early detection and quality and care continuum should be a public priority of multi-stakeholder collaboration in the Balkan region
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Global, regional, and national age-specific progress towards the 2020 milestones of the WHO End TB Strategy: a systematic analysis for the Global Burden of Disease Study 2021
Background
Global evaluations of the progress towards the WHO End TB Strategy 2020 interim milestones on mortality (35% reduction) and incidence (20% reduction) have not been age specific. We aimed to assess global, regional, and national-level burdens of and trends in tuberculosis and its risk factors across five separate age groups, from 1990 to 2021, and to report on age-specific progress between 2015 and 2020.
Methods
We used the Global Burden of Diseases, Injuries, and Risk Factors Study 2021 (GBD 2021) analytical framework to compute age-specific tuberculosis mortality and incidence estimates for 204 countries and territories (1990–2021 inclusive). We quantified tuberculosis mortality among individuals without HIV co-infection using 22 603 site-years of vital registration data, 1718 site-years of verbal autopsy data, 825 site-years of sample-based vital registration data, 680 site-years of mortality surveillance data, and 9 site-years of minimally invasive tissue sample (MITS) diagnoses data as inputs into the Cause of Death Ensemble modelling platform. Age-specific HIV and tuberculosis deaths were established with a population attributable fraction approach. We analysed all available population-based data sources, including prevalence surveys, annual case notifications, tuberculin surveys, and tuberculosis mortality, in DisMod-MR 2.1 to produce internally consistent age-specific estimates of tuberculosis incidence, prevalence, and mortality. We also estimated age-specific tuberculosis mortality without HIV co-infection that is attributable to the independent and combined effects of three risk factors (smoking, alcohol use, and diabetes). As a secondary analysis, we examined the potential impact of the COVID-19 pandemic on tuberculosis mortality without HIV co-infection by comparing expected tuberculosis deaths, modelled with trends in tuberculosis deaths from 2015 to 2019 in vital registration data, with observed tuberculosis deaths in 2020 and 2021 for countries with available cause-specific mortality data.
Findings
We estimated 9·40 million (95% uncertainty interval [UI] 8·36 to 10·5) tuberculosis incident cases and 1·35 million (1·23 to 1·52) deaths due to tuberculosis in 2021. At the global level, the all-age tuberculosis incidence rate declined by 6·26% (5·27 to 7·25) between 2015 and 2020 (the WHO End TB strategy evaluation period). 15 of 204 countries achieved a 20% decrease in all-age tuberculosis incidence between 2015 and 2020, eight of which were in western sub-Saharan Africa. When stratified by age, global tuberculosis incidence rates decreased by 16·5% (14·8 to 18·4) in children younger than 5 years, 16·2% (14·2 to 17·9) in those aged 5–14 years, 6·29% (5·05 to 7·70) in those aged 15–49 years, 5·72% (4·02 to 7·39) in those aged 50–69 years, and 8·48% (6·74 to 10·4) in those aged 70 years and older, from 2015 to 2020. Global tuberculosis deaths decreased by 11·9% (5·77 to 17·0) from 2015 to 2020. 17 countries attained a 35% reduction in deaths due to tuberculosis between 2015 and 2020, most of which were in eastern Europe (six countries) and central Europe (four countries). There was variable progress by age: a 35·3% (26·7 to 41·7) decrease in tuberculosis deaths in children younger than 5 years, a 29·5% (25·5 to 34·1) decrease in those aged 5–14 years, a 15·2% (10·0 to 20·2) decrease in those aged 15–49 years, a 7·97% (0·472 to 14·1) decrease in those aged 50–69 years, and a 3·29% (–5·56 to 9·07) decrease in those aged 70 years and older. Removing the combined effects of the three attributable risk factors would have reduced the number of all-age tuberculosis deaths from 1·39 million (1·28 to 1·54) to 1·00 million (0·703 to 1·23) in 2020, representing a 36·5% (21·5 to 54·8) reduction in tuberculosis deaths compared to those observed in 2015. 41 countries were included in our analysis of the impact of the COVID-19 pandemic on tuberculosis deaths without HIV co-infection in 2020, and 20 countries were included in the analysis for 2021. In 2020, 50 900 (95% CI 49 700 to 52 400) deaths were expected across all ages, compared to an observed 45 500 deaths, corresponding to 5340 (4070 to 6920) fewer deaths; in 2021, 39 600 (38 300 to 41 100) deaths were expected across all ages compared to an observed 39 000 deaths, corresponding to 657 (–713 to 2180) fewer deaths.
Interpretation
Despite accelerated progress in reducing the global burden of tuberculosis in the past decade, the world did not attain the first interim milestones of the WHO End TB Strategy in 2020. The pace of decline has been unequal with respect to age, with older adults (ie, those aged >50 years) having the slowest progress. As countries refine their national tuberculosis programmes and recalibrate for achieving the 2035 targets, they could consider learning from the strategies of countries that achieved the 2020 milestones, as well as consider targeted interventions to improve outcomes in older age groups
Environmental challenges for construction materials: potential use of calcined clay in cement
Concrete is the most widely used construction material for infrastructures and buildings. Cement, concrete’s key ingredient, has a dramatic carbon footprint as clinker production is responsible for about 7% of the world’s CO2 emissions. For this reason, European Standard EN 197-5 was updated in 2021 to allow formulation of new cement type containing from 50% to 64% of clinker, while previous versions allowed at minimum 65% of clinker, the main responsible for CO2 emission. This is made possible by a combination of limestone and calcined clay to replace partial clinker content.
The properties of the new Limestone Calcined Clay Cement (LC3) have been studied over the last few years in terms of chemistry and hydration, showing that this material exhibits promising properties concerning cement reactivity and sustainability. However, workability studies on calcined clay cements showed that higher amount of admixture is required to provide rheological properties comparable to Ordinary Portland Cement (OPC), with drastic influence on mechanical properties.
Analysis of literature studies and technical gaps that need to be further investigated will be presented to the scientific community to give an overview of the advances in construction materials, also providing some results from ongoing experimental research
Performance of concretes manufactured with newly developed low-clinker cements exposed to water and chlorides: Characterization by means of electrical impedance measurements
This paper discusses the electrical impedance behaviour, measured according to the Wenner's method, of three different concrete mixes during accelerated degradation tests. Being a first attempt to move from laboratory to in-field applications targeted to long-term monitoring, the same electrode array configuration and set-up (AC current at 10 kHz) is used. Results show that electrical impedance decreases down to 24% in capillary water absorption tests, 77% and 86% in salt-spray chamber and wet/dry cycles with 3.5% NaCl solution, respectively. The two new low-clinker cements adopted seem to improve the measurement sensitivity towards contaminants ingress with respect to the commercial one (reference)
Performance of concretes manufactured with newly developed low-clinker cements exposed to water and chlorides: Characterization by means of electrical impedance measurements
This paper discusses the electrical impedance behaviour, measured according to the Wenner’s method, of
three different concrete mixes during accelerated degradation tests. Being a first attempt to move from
laboratory to in-field applications targeted to long-term monitoring, the same electrode array configuration
and set-up (AC current at 10 kHz) is used. Results show that electrical impedance decreases down to
24% in capillary water absorption tests, 77% and 86% in salt-spray chamber and wet/dry cycles with 3.5%
NaCl solution, respectively. The two new low-clinker cements adopted seem to improve the measurement
sensitivity towards contaminants ingress with respect to the commercial one (reference)
Experimental study on 3D printing of concrete with overhangs
The construction industry has been receiving in the recent past years the 3D printing technology as an emerging technology. Several researchers and companies have been reporting a number of case studies that show the possibilities of this technology regarding the dimensions, shape, building time, finishing and the material characteristics. It is commonly accepted that one of the big advantages of 3D printing is its possibility regarding the shape of the printed object since it can be easily changed each time a new piece is printed. This possibility raises some challenges regarding the printing limits, that are needed to the project design, such as to create overhangs. In this sense, a work was carried out to evaluate and optimize concrete printing mixtures and assess the 3D concrete printing of elements with overhangs. This paper presents the work carried out, showing the optimization of mixture composition for the binder/aggregate ratio, cement/fly ash ratio, and amount of superplasticizer and hardening accelerator, and evaluating their printing performance and mechanical properties. Printing of overhangs was possible for angles with the vertical direction till 17.5º.info:eu-repo/semantics/publishedVersio