ECO2 framework assessment of limestone powder concrete slabs and columns

Producing limestone powder requires comparably far less energy than the production of ordinary Portland cement (OPC), making it a promising sustainable solution for partial replacement of OPC in concrete. Lower production energy could be translated into lower environmental impact and lower cost, which are two pillars of the sustainability of the resulting concrete. However, the question remains if replacing OPC with larger percentages of limestone powder would compromise the performance of the resulting concrete to a level that surpasses the environmental and economic gains. In order to assess the collective impact of these concretes, a performance-based multi-criteria decision analysis framework, ECO2, is used. For that purpose, 26 experimentally verified, concrete mixtures with and without limestone powder were evaluated through potential application in two types of reinforced concrete (RC) structural elements (slabs and columns) under identical environmental condition. The main results of the research showed a clear environmental advantage of concrete with a reduced OPC content, but the relatively higher superplasticizer amount in some cases could affect the final sustainability performance of the resulting mix. In the case of RC slabs, the best ECO2 score was obtained for concrete containing limestone powder. Mixtures with 200–250 kg of cement per unit volume of concrete had the highest ECO2 score for all the considered criteria. In the second case, due to the nature of the structural performance requirements in columns, the crucial influence of the concrete compressive strength is clear. The obtained results have shown approximately equal sustainability potential of OPC and limestone concretes in vertical elements such as columns. However, it seems that a certain improvement in the design of concrete mixtures with a high limestone powder content could make these competitive in all fields.This work was supported by the Ministry for Education, Science and Technology, Republic of Serbia [grant number TR36017].Peer ReviewedPostprint (published version

Pre-bcc: a novel integrated machine learning framework for predicting mechanical and durability properties of blended cement concrete

Partially replacing ordinary Portland cement (OPC) with low-carbon supplementary cementitious materials (SCMs) in blended cement concrete (BCC) is perceived as the most promising route for sustainable concrete production. Despite having a lower environmental impact, BCC could exhibit performance inferior to OPC in design-governing functional properties. Hence, concrete manufacturers and scientists have been seeking methods to predict the performance of BCC mixes in order to reduce the cost and time of experimentally testing all alternatives. Machine learning algorithms have been proven in other fields for treating large amounts of data drawing meaningful relationships between data accurately. However, the existing prediction models in the literature come short in covering a wide range of SCMs and/or functional properties. Considering this, in this study, a non-linear multi-layered machine learning regression model was created to predict the performance of a BCC mix for slump, strength, and resistance to carbonation and chloride ingress based on any of five prominent SCMs: fly ash, ground granulated blast furnace slag, silica fume, lime powder and calcined clay. A database from>150 peer-reviewed sources containing>1650 data points was created to train and test the model. The statistical performance was found to be comparable to that of existing models (R = 0.94–0.97). For the first time, the model, Pre-bcc, was also made available online for users to conduct their own prediction studies.Peer ReviewedPostprint (published version

Multi-recycling of polypropylene fibre reinforced concrete: Influence of recycled aggregate properties on new concrete

Herein, an investigation of multi-generational recyclability of polypropylene fibre reinforced concrete (PPFRC) was performed. The parent concretes were produced with 0 and 6 kg/m3 of polypropylene fibres. After recycling, the obtained coarse recycled concrete aggregates (RCAs) were used in new concrete with 0 and 6 kg/m3 of polypropylene fibres, repeating for three generations always with the same quantities of fibres. Properties of RCA, the mechanical properties of recycled aggregate concrete, the recovery rate of polypropylene fibres and the content of fibres embedded within the RCA were measured. The results of the study show that RCA obtained by PPFRC recycling offers significant benefits to new concrete production. This is achieved through the recovered fibres reintroduced into the new concrete, as well as through the fibres embedded in the recycled aggregates, leading to increased residual tensile strength.This study has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 836270. This support is gratefully acknowledged. The authors also wish to express their acknowledgement to the Ministry of Economy, Industry and Competitiveness of Spain for the financial support received under the scope of the projects PID2019-108978RB-C32. Any opinions, findings, conclusions, and/or recommendations in the paper are those of the authors and do not necessarily represent the views of the individuals or organizations acknowledged.Peer ReviewedPostprint (published version

Caracterización de los lodos de la depuradora de Sadat (Minufiya, Egipto) para la obtención de un material vitrocerámico

Muchos problemas ambientales actuales están relacionados con los desechos industriales y municipales (lodos de depuradora, etc.), debidos al gran volumen que se genera, así como a los elementos peligrosos que incluyen en ellos (metales pesados). Su almacenamiento, tratamiento y transporte conlleva también costos económicos. En Egipto en el año 2002 se generaron de 12 a 15 kg/año por habitante de materia sólida procedente de los lodos de depuradora. En la actualidad, el destino principal de estos lodos es su vertido en el desierto

Photostability of low cost dye-sensitized solar cells based on natural and synthetic dyes

Anthocyanin dye showed the maximum current efficiency η=0.27% •Application of natural pigments and synthetic dye sensitizers in dye-sensitized solar cells (DSSCs).•Photostability of the dyes over the TiO2 film electrodes.•The stability results favor selecting anthocyanin as a promising sensitizer candidate for DSSCs applications. This paper deals with the use of some natural pigments as well as synthetic dyes to act as sensitizers in dye-sensitized solar cells (DSSCs). Anthocyanin dye extracted from rosella (Hibiscus sabdariffa L.) flowers, the commercially available textile dye Remazole Red RB-133 (RR) and merocyanin-like dye based on 7-methyl coumarin are tested. The photostability of the three dyes is investigated under UV–Vis light exposure. The results show a relatively high stability of the three dyes. Moreover, the photostability of the solid dyes is studied over the TiO2 film electrodes. A very low decolorization rates are recorded as; rate constants k=1.6, 2.1 and 1.9×10−3min−1 for anthocyanin, RR and coumarin dyes, respectively. The stability results favor selecting anthocyanin as a promising sensitizer candidate in DSSCs based on natural products. Dyes-sensitized solar cells are fabricated and their conversion efficiency (η) is 0.27%, 0.14% and 0.001% for the anthocyanin, RR and coumarin dyes, respectively. Moreover, stability tests of the sealed cells based on anthocyanin and RR dyes are done under continuous light exposure of 100mWcm−2, reveals highly stable DSSCs

Signature of real-time PCR in detection of Trichomonas vaginalis infection and its association with human papillomavirus genotype 16

OBJECTIVE: Infection with Trichomonas vaginalis (TV) is the most prevalent non-viral sexually transmitted infection in the world. The objective of the study was to investigate the incidence of TV infection and its association with Human Papillomavirus (HPV) in a sample of Egyptian females. PATIENTS AND METHODS: 96 Egyptian females suspected for trichomoniasis were involved in our study. Vaginal washouts and cervical (cytobrush) samples were obtained from all patients and examined for T. vaginalis by direct wet mount, modified Diamond’s culture medium, and real-time PCR. Cervical (cytobrush) samples were examined for HPV using real-time PCR. RESULTS: Out of 96 patients, 28 (29%) was positive for T. vaginalis by real-time PCR. HPV was detected in 33 patients (34.4%); 31 cases (32.3%) were infected with HPV of genotype 16, whereas only two cases (2.1%) had genotype 18 infection. A significant association was found between TV and HPV infection [Odds ratio (OR)=10.58; 95% confidence interval (CI): 3.819 - 29.29; p<0.001]. CONCLUSIONS: When it comes to diagnosing trichomoniasis in a susceptible population, real-time PCR is more reliable than traditional standard approaches. A significant association between TV and HPV infection was found. Further research into the processes by which these two organisms interact at the cellular level could be revealed

Materiales vitrocerámicos a partir de lodos procedentes de una estación de depuración de aguas residuales urbanas (en la Ciudad de El-Sadat, Egipto)

La depuración de las aguas residuales urbanas es fuente de importantes volúmenes de lodos los cuales es preciso gestionar. En este trabajo se expone la posibilidad de aplicarles un proceso de gestión basado en la vitrificación y mediante el cual, además de inertizar los elementos contaminantes presentes en los lodos, se obtiene un material vitrocerámico con un importante valor añadido. Partiendo de la caracterización química (FRX), mineralógica (DRX) y térmica (ATD-TG) de estos lodos, se determina la formulación del vidrio original y su poder energético. Mediante ATD-TG, dilatometría y MEB, se ha determinado la temperatura de máxima velocidad de nucleación y la temperatura de crecimiento así como la morfología y tamaño de los núcleos formados que, en este caso, son nanométricos. En definitiva, se ha comprobado como la gestión de los residuos sólidos urbanos mediante la vitrificación es una alternativa a los vertederos y a la incineración