Compatibility between base concrete made with different chemical admixtures and surface hardener

Many cases of cracking and detachment of the concrete surface have appeared in concrete floors where surface hardeners were used in Portugal. The main causes for cracking and delamination of trowelled concrete pavements are several and it is essential to control bleeding and the time available to perform the finishing operations. Several base concretes were made with different chemical admixtures and one type of surface hardeners. The purpose of this study was evaluating the influence of the “open time” for each chemical admixture. Results show that the type of chemical admixture has a great importance in the control of the “open time” and consequently avoiding cracking and detachment

Compatibility between a quartz surface hardener and different base concrete mixtures

Many cases of cracking and detachment of the concrete surface have appeared in concrete floors, namely pavements where surface hardeners were used, especially in car parks, industrial areas and warehouses. This paper studies the behaviour of ten different base concretes mixtures made with two chemical admixtures and four additions, when a quartz surface hardener is applied. The objective is to identify the relevant parameters of the concrete constituents that influence the open time. Results show that the type of chemical admixture used to fabricate the concrete is important, but also the kind of admixture due to the water available to make the interconnection between the base concrete and surface hardener

INFLUÊNCIA DO BETÃO DE BASE EM PAVIMENTOS COM APLICAÇÃO DE ENDURECEDORES DE SUPERFÍCIE DE QUARTZO

Em Portugal e noutros países têm ocorrido frequentemente algumas situações anómalas em pavimentos com aplicação de endurecedores de superfície em betões de base, principalmente em zonas industriais e parques de estacionamento. A fissuração e o destacamento da camada superficial do betão estão entre as principais anomalias encontradas. O uso crescente de fortes redutores de água no betão e de ligantes cada vez mais finos com maiores conteúdos de silicato tricálcico podem ser algumas das causas para estes problemas. A resolução destas anomalias é bastante dispendiosa, já que estes tipos de betões são aplicados em grandes áreas. Além dessa situação também podem provocar atrasos no resto da construção. Este trabalho teve como objetivo analisar o comportamento de seis composições de betão de base diferentes. Na formulação das composições de base foram considerados dois adjuvantes e uma adição. Para o endurecedor de superfície foi apenas considerado um com minerais de quartzo, sendo que a aplicação do endurecedor e respetivo afagamento foi realizado por uma empresa especializada. Para a realização do trabalho foi escolhido um dia de Verão de maneira a simular situações mais extremas. O principal objetivo do estudo foi o de identificar os principais parâmetros dos constituintes do betão que influenciam o chamado “tempo aberto” para aplicação do endurecedor. Os resultados mostraram que a formulação da composição do betão de base tem grande influência no comportamento deste tipo de betões, assim como, a dimensão das equipas de trabalho que vão aplicar o endurecedor e efetuar o respetivo afagamento. Também o clima mostrou ter grande influência

Influence of steel slag type on concrete shrinkage

Building construction and building operations have a massive direct and indirect effect on the environment. Cement-based materials will remain essential to supply the growth of our built environment. Without preventive measures, this necessary demand in cement production will imply a substantial increase in CO2 generation. Reductions in global CO2 emissions due to cement consumption may be achieved by improvements on two main areas: increased use of low CO2 supplementary cementitious materials and a more efficient use of Portland cement clinker in mortars and concretes. The use of ground granulated blast furnace slag in concrete, as cement constituent or as latent hydraulic binder, is a current practice, but information of concrete with ladle furnace slag is more limited. Specific knowledge of the behavior of mixtures with steel slag in relation to certain properties needs to be improved. This paper presents the results of the shrinkage (total and autogenous) of five concrete mixtures, produced with different percentages of two different slags in substitution of cement. The results show that shrinkage of concrete with the two different slags diverges. These different characteristics of the two materials suggest that their use in combination can be useful in optimizing the performance of concrete.info:eu-repo/semantics/publishedVersio

A estação arqueológica das Boucinhas, Regueira, Vitorino de Piães, Ponte de Lima (Norte de Portugal)

Publicam-se os resultados das sondagens arqueológicas realizadas no povoado da Idade do Bronze da Boucinha, em Vitorino de Piães, Ponte de Lima.Projeto FCT: The Entre-Douro-e-Minho landscape since middle of 3rd to the end of 2nd millenia BC.info:eu-repo/semantics/publishedVersio

Verification of the presence of superabsorbent polymers (SAP) in fresh concrete : results of an interlaboratory study of RILEM TC 260-RSC

New methods are proposed for the verification of the presence of superabsorbent polymers (SAP) in freshly mixed concrete and estimation of SAP quantity. The methods are in general based on flushing concrete with excess water. They allow separating the light, water-sorbed hydrogel particles from the mineral components in the fresh concrete and making these particles available for further tests. Two types of tests are proposed: Test 1 serves for a visual verification of the presence of SAP (qualitative test), while Test 2 enables quantifying the mass of the collected SAP as a proxy of their concentration in concrete (quantitative test). Different procedures are proposed for these two test methods and their performance is evaluated. The testing procedures were scrutinized in an interlaboratory study carried out by 14 participants from 12 countries. All participating groups detected the presence of SAP in the mix using the qualitative procedures (Test 1). Based on this outcome, we suggest that this method should be applied in the field. In contrast, while most participants obtained reasonably reliable results with the quantification procedure of Test 2, some participants reported large errors. Therefore, the quantification method needs to be further refined, starting from the experience gained in this interlaboratory study.Open Access funding provided by Lib4RI.http://link.springer.com/journal/11527Civil EngineeringSDG-09: Industry, innovation and infrastructur

Influence of EPICardial adipose tissue in HEART diseases (EPICHEART) study: Protocol for a translational study in coronary atherosclerosis

Accumulation of epicardial adipose tissue (EAT) is associated with coronary artery disease (CAD) and increased risk of coronary events in asymptomatic subjects and low-risk patients, suggesting that EAT promotes atherosclerosis in its early stage. Recent studies have shown that the presence of CAD affects the properties of adjacent EAT, leading to dynamic changes in the molecular players involved in the interplay between EAT and the coronary arteries over the history of the disease. The role of EAT in late-stage CAD has not been investigated.coronárioResumoIntroduc¸ão:Acumulac¸ão de tecido adiposo epicárdico (TAE) tem sido associado a doenc¸acoronária aterosclerótica (DC) e aumento do risco de eventos coronários em indivíduos ass-intomáticos e doentes de baixo risco, sugerindo que o TAE pode promover fases precoces daDC. Estudo recentes mostraram que a presenc¸a de DC afeta as características do TAE adja-cente levando a modificac¸ões dinâmicas nos mediadores envolvidos na comunicac¸ão entre oTAE e as artérias coronárias ao longo da história da DC. O papel doTAE nas fases avanc¸adas daaterosclerose coronária não foi investigado.Objetivos: Através de análise comparativa com o tecido adiposo mediastínico e subcutâneo,pretendemos investigar se o volume do TAE, avaliado por tomografia computadorizada (TC), eo seu proteoma, avaliado por espectrometria de massa técnica de SWATH, estão associados aestadios avanc¸ados da DC numa coorte de estenose aórtica grave.Métodos: O estudo EPICHEART (NCT03280433) é um estudo prospetivo que inclui doentescom estenose aórtica grave referenciados para substituic¸ão eletiva da válvula aórtica, cujoprotocolo envolve avaliac¸ão pré-operatória clínica, nutricional, ecocardiográfica, por TC eangiografia coronária invasiva. Durante a cirurgia cardíaca, colhemos amostras de tecido adi-poso epicárdico, mediastínico e subcutâneo para análise do seu proteoma por espectrometriade massa técnica de SWATH. Adicionalmente, colhemos líquido pericárdico, sangue venoso per-iférico e do seio coronário para investigar mediadores de DC derivados do TAE na circulac¸ãosistémica e local.Conclusão: Desenhámos um estudo de translac¸ão para explorar a associac¸ão da quantidade equalidade do TAE com a DC tardia. Esperamos identificar mediadores da comunicac¸ão recíprocaentre o TAE e as artérias coronárias que estão envolvidos na patogénese das fases avanc¸adas daDC, especialmente, calcificac¸ão coronária, os quais podem servir como novos alvos terapêuticose soluc¸ões de engenharia biomédica para visualizac¸ão da DC

Testing superabsorbent polymer (SAP) sorption properties prior to implementation in concrete: results of a RILEM Round-Robin Test

This article presents the results of a round-robin test performed by 13 international research groups in the framework of the activities of the RILEM Technical Committee 260 RSC "Recommendations for use of superabsorbent polymers in concrete construction''. Two commercially available superabsorbent polymers (SAP) with different chemical compositions and gradings were tested in terms of their kinetics of absorption in different media; demineralized water, cement filtrate solution with a particular cement distributed to every participant and a local cement chosen by the participant. Two absorption test methods were considered; the tea-bag method and the filtration method. The absorption capacity was evaluated as a function of time. The results showed correspondence in behaviour of the SAPs among all participants, but also between the two test methods, even though high scatter was observed at early minutes of testing after immersion. The tea-bag method proved to be more practical in terms of time dependent study, whereby the filtration method showed less variation in the absorption capacity after 24 h. However, absorption followed by intrinsic, ionmediated desorption of a specific SAP sample in the course of time was not detected by the filtration method. This SAP-specific characteristic was only displayed by the tea-bag method. This demonstrates the practical applicability of both test methods, each one having their own strengths and weaknesses at distinct testing times

High-resolution multibeam bathymetry of the northern Mid-Atlantic Ridge at 45–46° N: the Moytirra hydrothermal field

This work presents a new high-resolution multibeam bathymetric map of a segment of active deep sea-floor spreading in the Atlantic Ocean, the northern Mid-Atlantic Ridge (MAR) at 45–46º N. New high-resolution bathymetry data were acquired using an Atlas multibeam echosounder onboard the research vessel Sarmiento de Gamboa during the EXPLOSEA-2 survey in 2019. The final map of the MAR (50 m cell grid size) at the original scale of 1:200,000 shows a segment of 140 × 35 km of the MAR, at water depths from 715 to 3700 m. This new high-resolution bathymetric map allows to better defining the submarine morphology of the Moytirra hydrothermal active field, the only high-temperature field identified between the Azores Archipelago (Portugal) and Iceland. ROV submarine observations reaching the deepest part of the system for the first time show giant anhydrite-sulfide chimneys up to 20 m high, active strong black smokers and polymetallic massive sulfides

Multidisciplinary Scientific Cruise to the Northern Mid-Atlantic Ridge and Azores Archipelago

This work presents the preliminary result of the multidisciplinary cruise EXPLOSEA2 surveying the northern Mid-Atlantic Ridge and Azores Archipelago from 46 300 N to 38 300 N aboard the R/V Sarmiento de Gamboa and ROV Luso over 54 days (June 11 to July 27, 2019). In this cruise report, we detail the geophysical, hydrographic, geological, oceanographic, ecological, and microbiological data acquired and a brief of main findings. The cruise addressed the exploration and comprehensive characterization of venting sites, including the water column, the sediments and rocks that host the hydrothermal activity, and the associated mineralizations, biology, and microbiology. Deep hydrothermal chimneys and massive sulfide deposits (up 3,000 m in depth) within the Moytirra hydrothermal active field were identified on slopes that had not been explored previously. Another striking finding made during the EXPLOSEA2 cruise was the field of carbonate chimneys named the “Magallanes-Elcano” field, a potentially relict ultramafic-hosted hydrothermal site sourced by abiotic methane. This field is related to a serpentinite and gabbro rock outcropping on a dome-shaped massif named the “Iberian Massif.” An outstanding finding of the EXPLOSEA2 survey was the identification of the first garden of soft corals growing after active submarine eruptions were reported in the Azores Archipelago composed by a high density of soft corals the suborder Alcyoniina at the summit and flanks of a recent volcanic cone at 160 m water depth developed during the 1957–1958 eruption of Capelinhos. Several cold-water coral habitats formed by colonial scleractinians (e.g., Lophelia pertusa and Madrepora oculata), coral gardens composed of mixed assemblages of black corals (Leiopathes sp.), and octocorals and dense aggregations of the glass sponge Pheronema carpenteri that may be classified as vulnerable marine ecosystems (VMEs) have been discovered during the EXPLOSEA2 cruise along the northern Mid-Atlantic Ridge. This work reveals the importance of multidisciplinary surveys to the knowledge of deep-sea environments