Construction and demolition waste as recycled aggregate for environmentally friendly concrete paving

Recycled aggregates (RA) from construction and demolition waste (CDW) instead of natural aggregates (NA) were analysed in the manufacture of new eco-friendly concrete. Fine (FRA) and coarse (CRA) recycled aggregates were used in different percentages as substitutes of natural sand and gravel, respectively. The results revealed that the use of RA in percentages of up to 50 wt.% is feasible. Additionally, RA were used to produce paving blocks in accordance with industrial requirements. Thus, values of water absorption lesser than 6.0% and tensile strength upper than 3.6 MPa were obtained, which are similar to those of a reference sample and within the limit values established by the regulations. These results were achieved by reducing the incorporation of cement, thereby saving production costs and minimizing environmental impact

Plan de negocio para el establecimiento de una empresa comercializadora de ropa informal para jóvenes entre 18 y 25 años de los estratos 3, 4, 5 y 6 para la ciudad de Bogotá D.C.

Administrador (a) de EmpresasPregrad

Occupational exposure to pesticides and endometrial cancer in the Screenwide case-control study

Background: Endometrial cancer is the most common gynaecological tumour in developed countries and disease burden is expected to increase over the years. Identifying modifiable risk factors may help developing strategies to reduce the expected increasing incidence of these neoplasms. Objective: This study evaluates the association between occupational exposure to pesticides and endometrial cancer using data from a recent case-control study in Spain. Methods: The analyses included data from 174 consecutive incident endometrial cancer cases and 216 hospital controls frequency-matched by age. Data were collected through structured epidemiological questionnaires and exposure to pesticides was assessed using a Spanish job-exposure matrix (MatEmESp). Results: Overall, 12% of controls and 18% of cases were occupationally exposed to pesticides. We observed a positive association between occupational exposure to pesticides and endometrial cancer (OR = 2.08; 95% CI = 1.13-3.88 compared to non-exposed). In general, exposures that occurred farther in the past were significantly associated with endometrial cancer. Exposure to insecticides, fungicides and herbicides were positively associated with endometrial cancer (OR = 2.08; 95% CI = 1.13-3.88, OR = 4.40; 95% CI = 1.65-13.33, and OR = 5.25; 95% CI = 1.84-17.67, respectively). The agricultural, poultry and livestock activities scenario was associated with endometrial cancer (OR = 4.16; 95% CI = 1.59-12.32), while the cleaning exposure scenario was not (OR = 1.22; 95% CI = 0.55-2.67). Conclusions: Assessment of occupational exposure to pesticides assessed using a Spanish job-exposure matrix revealed a positive association with endometrial cancer. The elucidation of the role of pesticide compounds on endometrial cancer should shed a light on the aetiology of this tumour

Consumption of aspartame and other artificial sweeteners and risk of cancer in the Spanish multicase‐control study (MCC‐Spain)

Use of artificial sweeteners (AS) such as aspartame, cyclamate, saccharin and sucralose is widespread. We evaluated the association of use of aspartame and other AS with cancer. In total 1881 colorectal, 1510 breast, 972 prostate and 351 stomach cancer and 109 chronic lymphocytic leukaemia (CLL) cases and 3629 population controls from the Spanish Multicase-Control (MCC-Spain) study were recruited (2008-2013). The consumption of AS, from table-top sweeteners and artificially sweetened beverages, was assessed through a self-administered and validated food frequency questionnaire (FFQ). Sex-specific quartiles among controls were determined to compare moderate consumers ( third quartile) vs non consumers (reference category), distinguishing aspartame-containing products and other AS. Unconditional logistic regression models were used to estimate adjusted OR and 95%CI, and results were stratified by diabetes status. Overall, we found no associations between the consumption of aspartame or other AS and cancer. Among participants with diabetes, high consumption of other AS was associated with colorectal cancer (OR=1.58, 95% CI 1.05-2.41, P trend=.03) and stomach cancer (OR=2.27 [0.99-5.44], P trend=.06). High consumption of aspartame, was associated with stomach cancer (OR=2.04 [0.7-5.4], P trend=.05), while a lower risk was observed for breast cancer (OR=0.28 [0.08-0.83], P trend=.03). In some cancers, the number of cases in participants with diabetes were small and results should be interpreted cautiously. We did not find associations between use of AS and cancer, but found associations between high consumption of aspartame and other AS and different cancer types among participants with diabetes

Valorisation of inorganic waste for obtaining construction materials

Waste generation, in general, increases with technological development, consequently the interest in environmental protection and health risks have grown in recent years. Therefore, it is necessary to develop strategies that has a beneficial impact on waste reuse and management trying to achieve sustainable development in which the resources used and the waste generated are minimised, as well as trying to achieve a circular economy, incorporating waste and co-products to new materials. This approach has already been included in the European Union waste strategies, prioritizing the prevention in waste generation, as well as the recycling and valorisation of wastes as alternative to their landfilling disposal. The main objective of this Doctoral Thesis was born out of the need to develop new efficient applications with commercial interest as construction materials (ceramics, cement and bricks), depending on the percentage of three types of inorganic residues: (1) Ilmenite mud generated in the production of TiO2 pigment, (2) phosphogypsum from the H3PO4 industry, and (3) construction and demolition waste (CDW). A number of instrumental techniques were deployed to characterise both the wastes used and the new materials designed, such as, X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), thermo-gravimetric analysis and differential scanning calorimetry (TGA/DSC) and scanning electron microscopy (SEM). In addition, the technological properties, such as resistance, water absorption, etc., have been compared in relation to traditional commercial materials and evaluated according to the established technical standards. Since, some of the wastes are considered NORM (Naturally Occurring Radioactive Material), the materials obtained were evaluated by alpha and gamma spectrometry, and the environmental implications (leaching and radiological studies) were evaluated. The most prominent findings of the present research can be divided under three main headings: Ilmenite mud Once the physical, chemical, granulometric, micro-structural and radiological properties of this waste were known, the design of new sulphur polymer cements and ceramic bodies adding different percentages were carried out. The results shown that ilmenite mud could be successfully immobilised and valorised as an additive. Theirs technological properties are in agreement with the requirements established in each regulations and, in some cases, the results were even better than those obtained by the reference materials. Finally, it can be concluded that that both materials can be used with negligible environmental impact or health risk. Phosphogypsum This waste has been valorised as an additive in ceramic manufacturing, complying with the international regulations for both technological properties and environmental requirements. Moreover, the addition up to 5 wt.% of phosphogypsum improves the technological properties in relation to the reference material. In addition, this waste has been studied as a calcium source for CO2 mineral sequestration and calcite production with high efficiencies (96 %). The study of the fluxes of metals and radionuclides showed that most of the phosphogypsum pollutants are transferred to calcite (> 95%). Construction and demolition waste (CDW) This waste has been recycled as substitute of natural aggregates to produce bricks. The results shown that low cost bricks with excellent technological properties can be obtained using CDW as an aggregate and lime or cement, as binders.La generación de residuos, en general, aumenta según incrementa el grado de desarrollo tecnológico de una sociedad, por lo que el interés por la protección del medio ambiente y los riesgos para la salud han florecido en los últimos años. Por tanto, desarrollar estrategias que mejoren la gestión de los residuos tratando de alcanzar un desarrollo sostenible en el que se minimicen los recursos utilizados y los residuos generados es muy necesario, así como tratar de alcanzar una economía circular, incorporando los residuos y co-productos a nuevos materiales. Este enfoque ya ha sido incluido en las estrategias de la Unión Europea en materia de residuos, priorizando la prevención en la generación de residuos, así como el reciclaje y la valorización de estos como alternativa a su depósito en vertedero. El objetivo principal de la presente Tesis Doctoral nace de la necesidad de desarrollar nuevas aplicaciones eficientes y de interés comercial en materiales de construcción (cerámicas, cementos y ladrillos), en base a diferentes porcentajes de tres tipos de residuos inorgánicos: (1) lodo de ilmenita generado en la producción de pigmento de TiO2, (2) fosfoyeso procedente de la industria del H3PO4, y (3) residuos de construcción y demolición (RCD). Para el estudio, tanto de la caracterización de los residuos como de los nuevos materiales diseñados, se han empleado diferentes técnicas instrumentales; entre otras, la difracción y la fluorescencia de rayos X (DRX/FRX), espectrometrías de masas o de emisión óptica con fuente de emisión por plasma de acoplamiento inductivo (ICP-MS/OES), análisis termo-gravimétrico y calorimétrico de barrido diferencial (TGA/DSC), y la microscopía electrónica de barrido (MEB). Las propiedades tecnológicas, como la resistencia, la absorción de agua, etc., han sido comparadas en relación a materiales comerciales tradicionales y evaluadas de acuerdo a los estándares técnicos establecidos. Como algunos de los residuos son considerados NORM (Naturally Occurring Radioactive Material = materiales radioactivos de origen natural), los materiales obtenidos fueron evaluados mediante espectrometría alfa y gamma, y también se evaluaron las implicaciones ambientales de su utilización (estudios de lixiviación y radiológicos). Los resultados más relevantes obtenidos de la presente Tesis Doctoral se pueden dividir en tres bloques: Lodo de ilmenita Una vez conocidas las propiedades físicas, químicas, granulométricas, micro-estructurales y radiológicas de este residuo se llevó a cabo el diseño de nuevos cementos poliméricos sulfurosos y cuerpos cerámicos, incorporando diferentes porcentajes. Los datos obtenidos demostraron que el lodo de ilmenita puede inmovilizarse y valorizarse con éxito al incluirlo como aditivo. Sus propiedades tecnológicas cumplieron sobradamente con los requisitos marcados en las diferentes regulaciones y, en algunos casos, fueron incluso mejores a las de los materiales de referencia. Finalmente, indicar que ambos materiales pueden ser usados sin generar problemas ambientales o de salud para las personas. Fosfoyeso Este residuo ha sido incluido como aditivo en cerámicas, las cuales has cumplido con las normativas internacionales vigentes en relación a las propiedades tecnológicas y con los requisitos ambientales establecidos. Incluso la adición de hasta 5 % de fosfoyeso mejora las propiedades tecnológicas en comparación al material de referencia. Este residuo también ha sido estudiado como fuente de calcio para el secuestro mineral del CO2 y obtención de calcita, obteniéndose altas eficiencias (96 %). El estudio de los flujos de metales y radionucleidos demostraron que la mayor parte de los contaminantes del fosfoyeso se transfieren a la calcita (> 95 %). RCD Este residuo ha sido reciclado como sustituto del agregado natural para la producción ladrillos. Los resultados muestran que pueden obtenerse ladrillos de bajo costo con excelentes propiedades físicas usando RCD como agregado, y cal o cemento como aglutinantes

Eco-Friendly Pavements Manufactured from Mixed Recycled Aggregates Obtained from Construction and Demolition Waste: An Industrial-Scale Validation

This study aimed to validate that laboratory-scale results could be commercially replicated when manufacturing marketable precast concrete. Construction and demolition waste (CDW) was separated into two (fine and coarse) recycled aggregates (RAs). Precast paver and kerb units were fabricated by partial or total substitution of natural aggregates (NAs) by RAs. The study involved the comprehensive characterisation of raw materials, including particle size distribution, mineral composition, and elemental composition. Paver blocks and kerbs manufactured with up to 50% RAs showed mechanical resistance (T = 3.7 ± 0.2 and B = 5.3 ± 0.6 MPa, respectively), water absorption between 5.3–5.7%, and abrasion resistance (approximately 20.2 mm), which met the standard requirements (UNE-EN 1340:2004 and UNE-EN 1338:2004). Furthermore, industrial-scale precast pavement units demonstrated strength and durability suitable for heavy traffic areas. A reduction of 13% in cement content could maintain the requirements with a partial RA substitution of 25%, offering economic and environmental benefits. Therefore, it is feasible at an industrial level to replace NAs with RAs, promoting durability and technological properties with a positive environmental impact and considerably reducing CO2 emissions by up to 65%. Overall, pavers with RAs manufactured at the laboratory scale met mechanical standards, and the kerb stones showed improvements in abrasion resistance. On an industrial scale, kerb stones and precast blocks with specific substitutions can meet strength, water absorption, and abrasion requirements, allowing a reduction in cement content

Valorisation of ilmenite mud waste in the manufacture of commercial ceramic

This paper reports the results of a study focused on the production of ceramic tiles from ilmenite mud (MUD), a waste generated by the industry devoted to the TiO2 pigment production. Ceramic tiles were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt.%). The samples were sintered to simulate a fast-firing process. The sintering behaviour of the fired samples was evaluated according to ISO methodologies by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, since this activity is a NORM (Naturally Occurring Radioactive Material) industry, the radionuclides activity concentrations were measured by both gamma and alpha spectrometry techniques. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of the use of undissolved mud tiles from an environmental perspective. The results obtained demonstrated that ilmenite mud can be successfully valorisated in the manufacture of red stoneware ceramic bodies, with even better technological properties than commercial ones. The addition of mud as additive (from 3% to 10%) had a beneficial effect to the sintering processes, improving the bending strength (up to 15%) and reducing both apparent porosity and water absorption (up to 50%)

Manufacture of ceramic bodies by using a mud waste from the TiO2 pigmentindustry

The main objective of this paper is focused in the use of a waste generated by the TiO2 pigment industry, ilmenite mud (MUD), on the production of ceramic bodies. These ceramic bodies were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt.%). The samples were sintered to simulate a fastfiring process. The sintering behaviour of the fired samples was evaluated by linear shrinkage, means of water absorption, apparent porosity and bulk density. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, the activity concentrations of radionuclides were measured by highresolution low-background gamma spectrometry, because this mud is a NORM (Naturally Occurring Radioactive Material) waste. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of use tiles from an environmental perspective. The results demonstrated that MUD can be successfully valorised in the manufacture of red stoneware ceramic bodies with similar or even better technological properties than commercialmaterials used currently

Valorisation of waste ilmenite mud in the manufacture of sulphur polymer cement

This paper reports the preparation of sulphur polymer cements (SPCs) incorporating waste ilmenite mud for use in concrete construction works. The ilmenite mud raw material and the mud-containing SPCs (IMC-SPCs) were characterised physico-chemically and radiologically. The optimal IMC-SPC mixture had a sulphur/mud ratio (w/w) of 1.05 (mud dose 20 wt%); this cement showed the greatest compressive strength (64 MPa) and the lowest water absorption coefficient (0.4 g cm−2 at 28 days). Since ilmenite mud is enriched in natural radionuclides, such as radium isotopes (2.0·103 Bq kg−1228Ra and 5.0·102 Bq kg−1226Ra), the IMC-SPCs were subjected to leaching experiments, which showed their environmental impact to be negligible. The activity concentration indices for the different radionuclides in the IMC-SPCs containing 10% and 20% ilmenite mud met the demands of international standards for materials used in the construction of non-residential buildings

New Adaptive High Starting Torque Scalar Control Scheme for Induction Motors Based on Passivity

A novel adaptive high starting torque (HST) scalar control scheme (SCS) for induction motors (IM) is proposed in this paper. It uses a new adaptive-passivity-based controller (APBC) proposed herein for a class of nonlinear systems, with linear explicit parametric dependence and linear stable internal dynamics, which encompasses the IM dynamical model. The main advantage of the HST-SCS includes the ability to move loads with starting-torque over the nominal torque with a simple and cost-effective implementation without needing a rotor speed sensor, variable observers, or parameter estimators. The proposed APBC is based on a direct control scheme using a normalized fixed gain (FG) to fine-tune the adaptive controller parameters. The basic SCS for induction motors (IM) and the HST-SCS were applied to an IM of 200 HP and tested using a real-time simulator controller OPAL-RT showing the achievement of the proposal goal