The improvement of inline mixer measurements is imposed in a growing concrete industry employing increasingly complex manufacturing processes. In this work we discuss an inline image analysis ...technique applied to the monitoring of concrete mixing, which is based on the evolution of the texture of pictures taken at the surface of the mixing bed. The method is used to study the evolution of the paste during processing in an intensive laboratory scale mixer for three different formulations: a hard-to-mix concrete, a self-compacting mortar and an easy to mix cement paste. The evolution of the texture allows obtaining important information on the evolution of the different formulations during mixing; in addition, the technique allows identifying with a good repeatability the main characteristic points of the mixture evolution, i.e. the cohesion time and the fluidity time.
Display omitted
•Inline image analysis technique is applied to the monitoring of concrete mixing.•Technique based on the evolution of the texture of pictures taken at the surface of the paste during mixing.•The evolution of the texture allows obtaining important information on the evolution of the different pastes.•The method proves to be very robust for a large range of formulations.
This work analyses the influence of fine concrete fractions (<5 mm) of different natures -calcareous (HcG) and siliceous (HsT)-obtained from construction and demolition waste (C&DW) on the behaviour ...of blended cement pastes with partial replacements between 5 and 10%. The two C&DW fractions were characterised by different instrumental techniques. Subsequently, their lime-fixing capacity and the physico-mechanical properties of the blended cement pastes were analysed. Lastly, the environmental benefits of reusing these fine wastes in the manufacture of future eco-efficient cement pastes were examined. The results show that HsT and HcG exhibit weak pozzolanic activity, owing to their low reactive silica and alumina content. Despite this, the new cement pastes meet the physical and mechanical requirements of the existing regulations for common cements. It should be highlighted that the blended cement pastes initially showed a coarser pore network, but then they underwent a refinement process between 2 and 28 days, along with a gain in compressive strength, possibly due to the double pozzolanic and filler effect of the wastes. The environmental viability of the blended cements was evaluated in a Life Cycle Assessment (LCA) concluding that the overall environmental impact could be reduced in the same proportion of the replacement rate. This is in line with the Circular Economy goals and the 2030 Agenda for Sustainable Development.
Construction and demolition waste (CDW) currently constitutes a waste stream with growing potential use as a secondary raw material in the manufacture of eco-cements that offer smaller carbon ...footprints and less clinker content than conventional cements. This study analyzes the physical and mechanical properties of two different cement types, ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and the synergy between them. These cements are manufactured with different types of CDW (fine fractions of concrete, glass and gypsum) and are intended for new technological applications in the construction sector. This paper addresses the chemical, physical, and mineralogical characterization of the starting materials, as well as the physical (water demand, setting time, soundness, water absorption by capillary action, heat of hydration, and microporosity) and mechanical behavior of the 11 cements selected, including the two reference cements (OPC and commercial CSA). From the analyses obtained, it should be noted that the addition of CDW to the cement matrix does not modify the amount of water by capillarity with respect to OPC cement, except for Labo CSA cement which increases by 15.7%, the calorimetric behavior of the mortars is different depending on the type of ternary and hybrid cement, and the mechanical resistance of the analysed mortars decreases. The results obtained show the favorable behavior of the ternary and hybrid cements made with this CDW. Despite the variations observed in the different types of cement, they all comply with the current standards applicable to commercial cements and open up a new opportunity to improve sustainability in the construction sector.
In recent years, the development of ternary cements has become a priority research line for obtaining cements with a lower carbon footprint, with the goal to contribute to achieve climate neutrality ...by 2050. This study compared ordinary Portland cement (OPC) durability to the performance of ternary cements bearing OPC plus 7% of a 2:1 binary blend of either calcareous (Hc) or siliceous (Hs) concrete waste fines and shatterproof glass. Durability was measured further to the existing legislation for testing concrete water absorption, effective porosity, pressurized water absorption and resistance to chlorides and CO
. The experimental findings showed that the 7% blended mortars performed better than the reference cement in terms of total and effective porosity, but they absorbed more pressurized water. They also exhibited lower CO
resistance, particularly in the calcareous blend, likely due to its higher porosity. Including the binary blend of CDW enhanced chloride resistance with diffusion coefficients of 2.9 × 10
m
s
(calcareous fines-glass, 7%Hc-G) and 1.5 × 10
m
s
(siliceous fines-glass, 7%Hs-G) compared to the reference cement's 4.3 × 10
m
s
. The siliceous fines-glass blend out-performed the calcareous blend in all the durability tests. As the mortars with and without CDW (construction and demolition waste) performed to similar standards overall, the former were deemed viable for the manufacture of future eco-efficient cements.
Concrete mixing can lead to mechanical degradation of aggregates, particularly when dealing with recycled concrete aggregates. In this work, the attrition of such materials during mixing is studied ...by means of experiments and simulations. The effect of the presence of fines, water addition, flow configuration of the mixer (co- or counter-current) and impeller frequency is discussed. Experiments were performed in a laboratory Eirich mixer. Discrete element numerical simulations (DEM) were performed on the same geometry by mimicking the behaviour of the material and, in particular, the cohesion induced by water and the cement paste using either Hertz–Mindlin or Hertz–Mindlin with Johnson–Kendall–Roberts (JKR) contact laws. The combination of the collision energy spectra extracted from the DEM simulations and an attrition model allowed the prediction of the mass loss due to attrition in 1-min experiments. Semi-quantitative agreement was observed between experiments and simulations, with a mean relative error of 26.4%. These showed that higher mass losses resulted from operation at the highest impeller speeds, co-current operation, and also with the wet aggregate. Mixing of the agglomerate in the concrete mix resulted in a significant reduction in attrition when compared to mixing aggregates alone. With further validation, the proposed simulation approach can become a valuable tool in the optimization of mixing by allowing the effects of material, machine and process variables to be studied on the mass loss due to attrition.
The coincidence of a study on different ecocements to environmental exposition in Madrid (Spain) with the airborne dust from the Sahara desert in the same location, during the year 2022, facilitated ...the knowledge of the ecocement permeability to different sources of contamination. In general, mortars with a siliceous composition are more compact and less permeable to environmental particles compared to those with a calcareous composition. Binary mortars with glass have an intermediate response to pollutants and the most favorable for the incidence of contamination are ternary sulfoaluminate cements. The analysis of the ions penetration in the different cements studied has been followed by XRF, XRD-Rietveld and SEM/EDX analyses.
•Recycled concrete aggregate (RCA) attrition during mixing was studied in two pilot mixers.•Mixing parameters and initial RCA properties influenced the breakage rate.•Both attrition and cleavage ...mechanisms influenced the aggregate degradation.•Angularity of the RCA was reduced by the mixing.
In this work, the recycled concrete aggregate (RCA) friability during mixing was studied in order to better understand the evolution of this material during the mixing process and improve the recycled aggregate concrete mix-design. The influence of some important materials and process parameters was evaluated: initial abrasion resistance and initial moisture of the aggregates, mixer geometry, mixing time and mixing speed. To assess the mixing process effect on the recycled concrete aggregate friability, three different aspects were evaluated; the mass loss (mass of fraction inferior to 2.5mm) the grading and the angularity evolutions with mixing time of an initially 10–14mm aggregate. Tests were carried out in two types of laboratory concrete mixers, a planetary 30l mixer from Skako and an intensive 5l Erich mixer. The results revealed that in normal laboratory setting of the mixers configuration, the mass loss for natural aggregate (NA) is less than 1% of the coarse aggregate. This percentage reach 3% for good quality recycled concrete aggregate (MDE value of 21) and 5% for lower quality recycled concrete aggregate (MDE value of 27). The mass loss directly depends on the mixing parameters and the degradation of the recycled concrete aggregate drastically increased when the mixing speed was raised to 500RPM. By analyzing the grading evolution during mixing, it was shown that both cleavage (creation of intermediate size particles) and attrition (creation of small particles) mechanisms influenced the aggregate degradation. However, the configuration of mixing significantly influenced the proportion of attrition and cleavage mechanisms. To complete this work, the angularity evolution showed that recycled concrete aggregate surface becomes smoother and the edges more rounded after mixing.
•Monitoring tools employed for analysing concretes and mortars mixing evolution.•The influence of water and coarse aggregate on the mixing evolution was analysed.•Difference between mixtures due to ...the wall effect exerted by coarse aggregates.•New mixture parameter defined: the “effective water-to-powder ratio in the mortar”.•Better estimation of the real effective water and of the fresh properties.
A new image analysis technique coupled with the power consumption were employed in this paper and proved to be a relevant method to detect the different characteristic times of the mixing evolution, i.e. the cohesion time, the fluidity time and the half-life time of the mixture evolution after fluidity. It was shown that the “effective water-to-powder ratio in the mortar” which excludes from the effective water the quantity of water needed to fill the less compact packing in the vicinity of the coarse aggregates, governed the mixing behaviour before fluidity and the interval of water content where the concrete mixture behaves as a homogenous and fluid granular suspension. It was also shown that the mixing behaviour was adversely affected by the amount of water into the mixture. The fluidity and cohesive times were faster to be obtained when the water proportion was increased. At opposite, it was more difficult to obtain the final consistency for a more fluid mixture, at given super-plasticizer proportioning. As a general remark, the behaviour seemed controlled by the mixture composition before the fluidity point and by the mixture consistency after the fluidity point. To end, the image analysis technique coupled with the mixing power technique can be employed at the end of the mixing to complete the information obtained with the other methods of analysis in order to monitor the consistency of the mixture. But, the use of the cohesion and fluidity times, easy to detect with the texture analysis, could be more efficient monitoring tools from an industrial point of view.
Liquid biopsies and the dynamic tracking of somatic mutations within circulating tumour DNA (ctDNA) can provide insight into the dynamics of cancer evolution and the intra-tumour heterogeneity that ...fuels treatment resistance. However, identifying and tracking dynamic changes in somatic copy number alterations (SCNAs), which have been associated with poor outcome and metastasis, using ctDNA is challenging. Pancreatic adenocarcinoma is a disease which has been considered to harbour early punctuated events in its evolution, leading to an early fitness peak, with minimal further subclonal evolution.
To interrogate the role of SCNAs in pancreatic adenocarcinoma cancer evolution, we applied whole-exome sequencing of 55 longitudinal cell-free DNA (cfDNA) samples taken from 24 patients (including 8 from whom a patient-derived xenograft (PDX) was derived) with metastatic disease prospectively recruited into a clinical trial. We developed a method, Aneuploidy in Circulating Tumour DNA (ACT-Discover), that leverages haplotype phasing of paired tumour biopsies or PDXs to identify SCNAs in cfDNA with greater sensitivity.
SCNAs were observed within 28 of 47 evaluable cfDNA samples. Of these events, 30% could only be identified by harnessing the haplotype-aware approach leveraged in ACT-Discover. The exceptional purity of PDX tumours enabled near-complete phasing of genomic regions in allelic imbalance, highlighting an important auxiliary function of PDXs. Finally, although the classical model of pancreatic cancer evolution emphasises the importance of early, homogenous somatic events as a key requirement for cancer development, ACT-Discover identified substantial heterogeneity of SCNAs, including parallel focal and arm-level events, affecting different parental alleles within individual tumours. Indeed, ongoing acquisition of SCNAs was identified within tumours throughout the disease course, including within an untreated metastatic tumour.
This work demonstrates the power of haplotype phasing to study genomic variation in cfDNA samples and reveals undiscovered intra-tumour heterogeneity with important scientific and clinical implications. Implementation of ACT-Discover could lead to important insights from existing cohorts or underpin future prospective studies seeking to characterise the landscape of tumour evolution through liquid biopsy.
Introducción: Establecer una adecuada comunicación forma parte del proceso terapéutico y del abordaje integral del paciente oncológico. El protocolo SPIKES emite una serie de recomendaciones ...generales destinadas a facilitar este proceso. No existe hasta la fecha un cuestionario que permita personalizar de una manera sistematizada la comunicación de malas noticias. Existen estudios que apoyan la hipótesis de que la personalidad influye en los modos comunicativos. Por ello, el objetivo de este trabajo fue intentar establecer matices en el protocolo SPIKES con base en los rasgos de personalidad. Materiales y métodos: Estudio unicéntrico, observacional, prospectivo, descriptivo y correlacional, realizado sobre una muestra de 51 pacientes oncológicos con base en un cuestionario de personalidad y un cuestionario de comunicación, el cual se basa a su vez en el protocolo SPIKES. Resultados: Las puntuaciones registradas en todos los dominios del cuestionario de comunicación fueron elevadas. Ninguna correlación con los dominios del cuestionario de personalidad resultó significativa. Conclusiones: Existen determinadas necesidades tendentes a la universalidad en torno a la comunicación de malas noticias que el protocolo SPIKES recoge adecuadamente, por lo que puede considerarse el gold standard. No se pueden establecer matices en este cuestionario en función de los rasgos de personalidad con base en los resultados de este trabajo. En la fase de estrategia, conviene prestar atención a la planificación vital y familiar en el seno de la enfermedad oncológica.
PDF
