Waste tire rubber particles modified by gamma radiation and their use as modifiers of concrete

En este trabajo se produjo concreto añadiendo hule de llantas de desecho, posteriormente se irradió con rayos gamma, para finalmente evaluar sus propiedades mecánicas. Los efectos de la radiación en el hule de llanta se evaluaron con diferentes técnicas analíticas.in this work, cement concrete specimens were produced with cement, water, rock crushed and sand; this last was partially substituted by particles of waste tire rubber. Then the compression properties of the specimens were evaluated following the experimental parameters: a) gamma irradiation dose (200, 250 and 300 kGy), b) particle size of tire rubber (0.85 and 2.8 mm), and c) particulate concentration of tire rubber (1, 3 and 5 wt. %). In addition, the mechanical compression results were related with the changes on the physicochemical properties of the irradiated tire particles, which were analyzed by FT-IR, Raman, UV–vis, SEM, XRD, TGA and DSC

Patch loading in slender and high depth steel panels: FEM–DOE analyses and bridge launching application

This paper studies the optimum way to design both type and position of the stiffeners when a steel bridge is assembled by means of the new protect-patented launching method based on a self-supporting deck system. This procedure is able to launch bridge up to a span of 150 m, in an economical and sustainable way. The main objective of this research paper is to numerically analyze the best stiffener combination and distribution along the length of bridge, both longitudinally and transversally, in order to avoid the patch-loading phenomenon in the slender webs. An optimum design of a triangular cell along the lower plate is also presented. Thus the best stiffener distribution along the deck can be achieved to solve the two most important factors during the launching of a steel bridge: the huge forces on the support section – higher than the serviceability limit state – and buckling instability due to the point loads on the bearings. In this way, a three dimensional finite element model (FEM) is built and the design of experiments technique (DOE) is applied to obtain the best stiffener configuration. The numerical simulation allows the exact definition of the response of the structure to be achieved, covering the gaps and limits which are common in some national and international codes. Very good results have been obtained, in terms of deflection, patch loading resistance and vertical load distribution on the support section. Finally, the most important conclusions of this work are given.The authors wish to acknowledge the financial support provided by the Spanish Ministry of Science and Innovation with funds from ALCANZA Research Project number IPT-380000-2010-12 and BIA-2012-31609

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Thermal and structural optimization of lightweight concrete mixtures to manufacture composite slabs

The use of composite slabs in buildings is increasingly widespread in the EU in the last decades. Current standards specified the minimum concrete compressive strength used in its manufacture as 25 MPa. The aim of this work is to study different lightweight concrete mixtures to manufacture composite slabs, taking into account their thermal and structural properties, such as termal conductivity and compressive strength. Firstly, design of experiments methodology was used to study different formulations of lightweight concrete mixtures. Secondly, a test protocol was established in order to maintain the máximum homogeneity in the samples. Thirdly, structural and thermal tests were done and the experimental results were analyzed. Results of compressive strength varies between 14.90 to 27.43 MPa and thermal conductivity are between 0.68 to 0.93 W/mK. Finally, the concrete mixtures was optimized and four were chosen as the most suitable ones for its use in this type of slabs.Los autores agradecen a la Fundación para el Fomento en Asturias de la Investigación Científica Aplicada y la Tecnología (FICYT) y al Ministerio de Ciencia, Innovación y Universidades del gobierno de España las ayudas recibidas a través de los proyectos FC-GRUPIN-IDI/2018/000221 y PGC2018-098459-B-I00 respectivamente, ambos financiados con fondos FEDER

Thermal and structural optimization of lightweight concrete mixtures to manufacture composite slabs

The use of composite slabs in buildings is increasingly widespread in the EU in the last decades. Current standards specified the minimum concrete compressive strength used in its manufacture as 25 MPa. The aim of this work is to study different lightweight concrete mixtures to manufacture composite slabs, taking into account their thermal and structural properties, such as termal conductivity and compressive strength. Firstly, design of experiments methodology was used to study different formulations of lightweight concrete mixtures. Secondly, a test protocol was established in order to maintain the máximum homogeneity in the samples. Thirdly, structural and thermal tests were done and the experimental results were analyzed. Results of compressive strength varies between 14.90 to 27.43 MPa and thermal conductivity are between 0.68 to 0.93 W/mK. Finally, the concrete mixtures was optimized and four were chosen as the most suitable ones for its use in this type of slabs.Los autores agradecen a la Fundación para el Fomento en Asturias de la Investigación Científica Aplicada y la Tecnología (FICYT) y al Ministerio de Ciencia, Innovación y Universidades del gobierno de España las ayudas recibidas a través de los proyectos FC-GRUPIN-IDI/2018/000221 y PGC2018-098459-B-I00 respectivamente, ambos financiados con fondos FEDER