Eco-friendly isolant composite mortars based on natural pozzolan, fly ash and plastic fibers

Thermal insulation in buildings has gained significant attention recently due to the clear benefits of selecting appropriate insulation materials for energy conservation. This study presents experimental research conducted to evaluate the thermal properties of mortar based natural Moroccan pozzolan and fly ash, both of which serve as alternatives to cement powder. Unlike cement, which requires energy-intensive extraction, natural pozzolan is an abundant volcanic material, and fly ash is a powdery residu generated as a byproduct during the combustion of coal in thermal power plants. The aim of this research is to explore the potential of these materials for thermal insulation and to address the environmental concern of plastic waste management through recycling. Twenty different mortar mixes were synthesized and evaluated, with a constant 10% of fly ash and varying percentages (10%, 20%, 30%, 40%) of natural pozzolan replacing cement. Additionally, 1% of plastic fibers based on the mortar volume were included. Thermal conductivity and heat capacity of the cured mortar mixtures were measured after 7 and 14 days using a TPS1500 hot disc Analyzer, which is currently the most precise and useful method for studying thermal transport parameters. To ensure consistent conditions, all samples were preconditioned to eliminate moisture before testing. The test results indicated the potential of using plastic fibers, fly ash, and natural pozzolan as effective thermal insulation materials. These materials demonstrated reduced thermal conductivity and increased specific heat capacity, making them desirable for building applications. From an economic and environmental standpoint, incorporating them as cement substitutes for sustainable cement production in thermal insulation is the most favorable approach

Parametric Study of a Soil Erosion Control Technique: Concrete Lozenges Channels

A new technique, "the concrete lozenges channels" is described in this paper. It is an erosion control measure to attenuate the water soil loss quantity to a tolerable level. These are open inclined channels that form lozenges on the slope. In fact, they drain rainfall, runoff, and sediments alongside the slope into the ditch. Using the RUSLE erosion model for erosion assessment, the parameters that had the most influence on the percentage decrease of the soil erodibility are discussed. A comparison between techniques already used, that is, the concrete arches and the concrete lozenge channels proposed in this paper, makes it possible to mention the shortcomings and the strengths of each technique. In fact, the percentage decrease in erosion soil loss is about 42% for 2 arches and is about 49% for 2 lozenges. If the number of channels present on the slope increases, the area exposed to erosion decreases. By comparing the study case, the exposed area for one lozenge is less by 39% to 68% than the exposed area for one arch. The total perimeter lengths are comparable. In this article, a parametric study is undertaken to define the optimum dimensions and optimum number of concrete inclined channels. The ditch section and the inclined channel section are determining factors in the lozenge sizing. Doi: 10.28991/CEJ-2022-08-09-09 Full Text: PD

Evaluation of Liquefaction Potential based on Cone Penetration Test (CPT) and Semi-empirical Methods

The phenomenon of soil liquefaction can be an induced effect of earthquake shaking where the saturated soil loses some or all of its bearing capacity and stiffness. Likewise, the increase of water pressure in the soil pores under the seismic wave causes a decrease of the shear strength. As a result, the soil becomes liquefied and susceptible to producing permanent deformations. The phenomenon of liquefaction is generally unpredictable, and neglecting it can influence the stability of structures and infrastructure foundations. Since the 1964 Alaska and Niigata earthquakes, more research works have been conducted to assess land liquefaction vulnerability. This study is undertaken in this field, whose objective, on the one hand, is to signal the phenomenon of liquefaction in the north of Morocco as a geo-technical part known for its instability and, on the other hand, to study the semi-empirical methods to adequately evaluate the liquefaction potential while specifying the most appropriate method for our case study. Similarly, the study is based on data derived from experimental results of in-situ tests applied to the embankment crossing the valley of "Oued Gharifa" on a high-speed rail line section from KP 228+400 to KP 229+375. Moreover, this research aims to show and discuss the evaluation of liquefaction potential of the experimental results of the CPT (cone penetration test) using three semi-empirical methods, namely the Juang method, the Olsen method, and the Robertson method. In doing so, we are going to compare the application results of the three semi-empirical methods in light of evaluating the liquefaction likelihood of the studied area, taking into account the nature of the soil, the variation of the safety coefficient, and the liquefaction potential for each method as well. Doi: 10.28991/CEJ-2023-09-02-013 Full Text: PD

Synergizing multi-criteria diagnosis for safeguarding cultural heritage and the restoration of vanished legacy: A historical exploration in science, technology, and archaeology

The urgent need to preserve cultural heritage is starkly evident in contemporary society, particularly poignant in Morocco where its rich cultural legacy faces unprecedented threats. The rapid forces of urbanization and relentless economic development have converged, resulting in the alarming devaluation and irreversible degradation of a substantial portion of this invaluable heritage. Within this disconcerting backdrop, certain remarkable vestiges have managed to endure the ravages of time. One such exemplar is the Marinid Madrasa, an architectural marvel from the 4th century, nestled within the Chellah archaeological site in Rabat, Morocco. Beyond its physical grandeur, the Madrasa plays a pivotal role as a conduit between the past and the future, facilitating the transmission of cultural heritage to generations yet unborn. This paper embarks on a multidisciplinary journey, employing advanced techniques such as terrestrial photogrammetry, numerical modeling, and specialized archaeological characterization, to undertake comprehensive diagnostic study processes. The convergence of these diverse methodologies lays a robust foundation for a holistic diagnostic study. This endeavor serves not only academic curiosity but becomes the cornerstone upon which strategies for compatible conservation and restoration interventions are erected. In the intricate interplay between historical preservation and the imperatives of progress, these methodologies form a bridge. This bridge links the architectural magnificence of the Madrasa with the imperatives of safeguarding it in a rapidly changing world. The ultimate aspiration of this multidisciplinary approach is twofold: to ensure the enduring protection of the Marinid Madrasa and other archaeological remnants against the erosive forces of time and urban development, and to forge a narrative that sensitively navigates the challenges posed by preserving cultural heritage in the face of modernity. In this endeavor, advanced technologies are interwoven with a profound recognition of the historical, social, and cultural significance of these sites, ultimately charting a course that not only conserves architectural brilliance but also honors the profound stories they encapsulate across the epochs

Geostatistical Analysis for delineating sterile inclusions in Sidi Chennane' phosphatic series, Morrocco

The anomalies detected in phosphatic series of Sidi Chennane, one of phosphatic basins in Morocco, hinder the proper exploitation of phosphate levels and the assessing phosphate reserves seems incorrect. The purpose of this study was the evaluation of geostatistical methods for delimitation of these disturbances. To cover all the zones being able to be disturbed, we carried out, during the geophysical prospection in a parcel of 50 ha, 5151 resistivity measurements as horizontal profiling using the well-known Schlumberger array, in order to map the spatial distribution of  the sterile hardpan inclusions.Geostatistical tools were used to quantify the spatial correlation between apparent resistivity data. Semivariograms were obtained using a classical Matheron semivariogram estimator and fit to the experimental semivariograms obtained. We have selected those with the best fit in terms of sum of squared residuals (SSR).Geostatistical analysis was performed using the software VESPER 1.63. Spatial distribution maps were made by ordinary kriging, the qualitative interpretation of these maps reflects that the exponential model is found to be the best model representing the spatial variability of our geoelectric data. The qualitative interpretation of the kriged resistivity maps allows defining resistivity contrast, consequently we have delimited the crossing dominate area from a “normal” into a “disturbed” area. Models of the geology were successfully obtained from geostatical method, which help mapping the phosphate deposit inclusions and the estimations of phosphate reserves were improved and better constrained. ResumenLas anomalías detectadas en las series fosfóricas de Sidi Chennane, una de las cuencas fosfóricas de Marruecos, dificultan la explotación apropiada de los niveles de fosfato y hacen parecer incorrectos los cálculos de las reservas. El propósito de este estudio es la evaluación de los métodos geoestadísticos para la delimitación de estas anomalías. Para cubrir todas las zonas donde se pueden presentar estas alteraciones se llevaron a cabo,durante la exploración geofísica en una parcela de 50 hectáreas, 5151 medidas de resistividad con perfileshorizontales a través del conocido sondeo Schlumberger, con el fin de mapear la distribución espacial de las inclusiones estériles de la capa sólida.Se utilizaron herramientas geoestadísticas para cuantificar la correlación espacial entre los datos de resistividad. Se obtuvieron semivariogramas a través del tradicional estimador de semivariogramas Matheron y se adecuaron a los semivariogramas experimentales obtenidos. La selección se basó en aquellos que mejor se acoplaban en términos de la suma de cuadrados residuales (SCE). Los análisis geoestadísticos se realizaron con el programa VESPER 1.63. Los mapas de distribución espacial se hicieron por Kriging regular, y la interpretación cualitativa de estos mapas refleja que el modelo exponencial es el que mejor representa la variablilidad espacial de estos datos geoeléctricos. La interpretación cualitativa de los mapas de resistividad obtenidos por la técnica del Kriging permite definir el contraste de resistencia, lo que fija el área entre los estándares de “normal” y “Con Alteraciones”. Los modelos geológicos fueron obtenidos del método geoestadístico, lo que ayudó a mapear los depósitos de inclusiones de fosfato y mejoró las estimaciones de las reservas a través de una mejor definición de estas

Comparative analysis of swelling mitigation in marl and clay soils: natural plant fibers (Alfa, jute, sisal) vs. polypropylene fiber with lime-pozzolana cement utilizing proctor compaction

This study offers a comparative assessment of two methodologies for mitigating soil swelling in marl and clay soils. The methods under investigation include the use of natural plant fibers (Alfa, jute, sisal) and polypropylene fibers in combination with lime-pozzolana cement. Laboratory tests, including Proctor compaction tests, and swell potential assessments, were conducted to assess the effectiveness of each method. The findings reveal that both natural plant fibers and polypropylene fibers, when combined with lime-pozzolana cement, effectively reduce soil swelling. The study underscores the promise of eco-friendly natural plant fibers and the durability of polypropylene fibers as viable solutions for soil stabilization. Furthermore, incorporating lime-pozzolana cement enhances both methods performance, providing an additional layer of soil stability. This research contributes valuable insights to geotechnical engineering projects dealing with marl and clay soils. It aids in the selection of suitable soil stabilization techniques, considering project-specific needs and sustainability concerns. Ultimately, this study advances the field of geotechnical engineering by promoting environmentally conscious and resilient solutions to address soil swelling in clay and marl soils

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa.

The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century