Quality improvement of mixed and ceramic recycled aggregates by biodeposition of calcium carbonate

This research focuses on improving the quality of mixed and ceramic recycled aggregates by microbially induced carbonate precipitation (Bacillus sphaericus). The precipitation contributed to a weight increase and unleashed a waterproofing response. The roughness of the ceramic particles created a more uniform layer compared to natural or concrete particles. For the concrete fraction, which had a higher macroporosity, the consolidation effect was more pronounced. High ceramic content aggregates profited from a greater biodeposition, leading to a remaining amount of precipitates after sonication which was still greater than in cementitious materials. Pore-filling effect was detected by SEM, supporting the waterproofing result. (C) 2017 Elsevier Ltd. All rights reserved

Biodegradable polymers on cementitious materials

PTDC/EPH-PAT/4684/2014 IF/01054/2014/CP1224/CT0005 UID/QUI/50006/2019 UID/Multi/04378/2019 POCI-01-0145-FEDER-007728Nowadays the sustainability and safety requirements of structures inspire the study of new self healing materials and preventive repair methods on cementitious elements. To achieve this undertaking, this research replaces widely employed synthetic polymers by biodegradable ones as consolidants and water-repellents, and assesses the protection and consolidation effect of biopolymers (obtained by using waste biomass of mixed microbial cultures from polyhydroxyalkanoates production processes) as eco-friendly healing agents by analysing the water absorption of two kind of materials. The first group of samples are cement mortar specimens whose external surface has been treated with biopolymer products and subsequently evaluated by water drop absorption test. The second group of samples are cement mortar specimens formulated with biopolymer products included in its mixing water and later the waterproofing efficiency is analysed by capillary water absorption tests. The water absorption behaviour of both kind of samples shows a potential improvement of cementitious elements durability, since water absorption results have decreased for treated samples in comparison with untreated ones.authorsversionpublishe

Eco-friendly healing agents for recycled concrete

Abstract An innovative option to extend the service life of construction and building materials is the use of bio-healing agents. This study was focused on assessing the protection and consolidation effect of eco-friendly healing agents by analysing the water absorption of recycled concrete. A recycled concrete with 50% replacement of natural coarse aggregate by construction and demolition waste (CDW) aggregate and a similar recycled concrete in which, additionally, the Portland cement was replaced by recycled cement (with 25% ceramic waste) were biotreated by healing agents. These agents were obtained by using waste biomass of two different mixed microbial cultures from polyhydroxyalkanoates production processes. Results have shown that biotreatments decreased the water absorption significantly, more evident in concrete samples with both recycled cement and aggregates than on the other type of concrete. Resumen Una innovadora posibilidad planteada para prolongar la vida útil de los materiales de construcción y edificación es el uso de agentes bioreparadores. Este estudio se centró en la evaluación del efecto protector y consolidante de agentes reparadores y respetuosos con el medio ambiente mediante el análisis de la absorción de agua del hormigón reciclado. Un hormigón reciclado con sustitución del 50% de los áridos gruesos naturales por residuos de construcción y demolición (RCD) y un hormigón reciclado similar en el cual, además, se sustituyó el cemento convencional Portland por cemento reciclado (con 25% de residuo cerámico) fueron biotratados con agentes reparadores. Estos agentes se obtuvieron en el proceso de producción de polihidroxialcanoatos utilizando biomasa residual de dos cultivos microbianos mixtos diferentes. Los resultados mostraron que los biotratamientos disminuyen significativamente la absorción de agua del hormigón, siendo más eficaces en las muestras de hormigón que combinan cemento y árido reciclado que en el otro tipo de hormigón.authorsversionpublishe

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Paving with precast concrete made with recycled mixed ceramic aggregates : a viable technical option for the valorization of Construction and Demolition Wastes (CDW)

This research aimed to prove the feasibility of producing two types of precast elements widely used in construction, such as curbstones and paving blocks, using recycled concrete made with a 50% substitution of the natural gravel by recycled mixed aggregates with a significant ceramic content (>30%). In order to prove the quality of such mass concrete recycled precast elements, two different mixes were used: the first one was a conventional concrete mix provided by Prefabricados de Hormigon Pavimentos Paramo S.L., one of the collaborating companies in this study, and the other was a mixture in which wt 50% of the natural coarse aggregates were substituted for recycled mixed aggregates ceramic (RMAc). This recycled aggregate is a heterogeneous mixture of unbound aggregates, concrete, ceramic, etc., used as a secondary recycled aggregate and commonly produced in a lot of recycling plants in many European countries. This material was supplied by Tecnologia y Reciclado S.L., the other collaborating company. Both mixtures were representative in order to establish the comparative behavior between them, taking into account that smaller percentages of replacement of the natural with recycled aggregates will also produce good results. This percentage of substitution represents a high saving of natural resources (gravel) and maintains a balanced behavior of the recycled concrete, so this new material can be considered to be a viable and reliable option for precast mass concrete paving elements. The characterization of the recycled precast elements, covering mechanical, microstructural, and durability properties, showed mostly similar behavior when compared to the analogous industrially-produced pieces made with conventional concrete

Study of recycled concrete durability increase with biololymers

Una innovadora posibilidad planteada para prolongar la vida útil de los materiales de construcción y edificación es el uso de agentes biorreparadores. Este estudio se centró en la evaluación del efecto protector de agentes reparadores, y a la vez respetuosos con el medio ambiente, mediante el análisis de la absorción superficial de agua en el hormigón reciclado. Se ha ensayado un hormigón reciclado en el que una parte del árido grueso natural ha sido sustituida por residuos de construcción y demolición (RCD), y otro hormigón similar en el cual, además, se sustituyó el cemento convencional Portland por cemento reciclado. Estos hormigones fueron recubiertos superficialmente con biopolímeros obtenidos en el proceso de producción de polihidroxialcanoatos utilizando biomasa residual de dos cultivos microbianos mixtos diferentes. Los resultados mostraron que disminuye significativamente la absorción de agua en el hormigón, siendo más eficaces en las muestras de hormigón reciclado con cemento reciclado.publishersversionpublishe