Micromorphological description of vernacular cob process and comparison with rammed earth

International audiencePast builders have developed very low-embodied energy construction techniques optimizing the use of local building materials. These techniques are a source of inspiration for modern sustainable building. Unfortunately, this know-how was orally transmitted andwas lost as earth construction fell into disuse during the 20th century in European countries.The absence of written documents makes necessary to use an archaeological approach in orderto rediscover these construction strategies. Micromorphological analysis of thin sections collected in earth building walls was used for the first time to describe cob construction tech-nique and highlighted several typical pedofeatures allowing to clearly identifying this process.Finally, a first comparison of the cob and rammed earth micromorphological features permitted to identify two key factors to distinguish these two techniques, the manufacturing state (solid or plastic) and the organization of the material in the wall

Elasto-plastic model for sand including time effect

Time effects on granular soils have been observed in the laboratory and by in-situ tests, but these cannot be reproduced by classical elasto-plastic models. To address these concerns, existing specific modelling approaches were based on the theory of viscoplasticity formulated by Perzyna or on a viscous evanescent relationship. This work explores an alternative elasto-plastic modelling framework formulated in a multiaxial structure space. The proposed elasto-plastic model is associated with a thixotropic-type framework through the use of a structure parameter, the evolution of which illustrates the competition between two effects: the time-dependent tendency of the granular system to reach its stable configuration - restructuration - and its destructuration under external perturbations. The structure parameter is linked to the existence of a stress-dependent target structure towards which the current granular material structure evolves. The timescale is explicitly introduced by postulating a rate for this structure evolution. The modelling of the material behaviour has shown good similarities with the response of granular soils observed in monotonic loading, as well as during creep and variable strain rate loading experiments

Transplant of faecal microbiota - priority area in the agenda to eradicate clostridium difficile infection

Department of Microbiology, Virology and Immunology, Nicolae Testemitanu State University of Medicine and Pharmacy, Chisinau, Republic of Moldova, The 6th International Medical Congress for Students and Young DoctorsIntroduction: Fecal transplant or transplant of fecal microbiota (TFM) is an innovative technique of transplantation of fecal bacteria from a healthy person to a sick one. For the first time it was used by experts from the University Hospital "Hadassah"(Ierusalim) to treat certain intestinal diseases, especially the ones caused by the bacterium Clostridium difficile. This microorganism is found in intestines of people of different ages, but the increasing number of these bacteria inhibits the normal micro-flora of the intestinal tract inside healthy people. When the optimum balance in the gut is disrupted (often as a result of antibiotic treatment), there is a rapid increase of Clostridium difficile, which leads to diseases.C.difficile is estimated to be responsible for at least one fourth of antibiotic-Associated diarrheas in hospitalized patients. Studies that have been done in this field have contributed to the progress in getting known the TFM. The recovery of patients were successful in more than 90% after the manipulations which were performed, these being recognized as the most important scientific achievements of 2012. Material and methods: The presentation represents an extensive literature review based on previously completed research; we have conducted its own study and concluded the benefit of this procedure for the treatment of patients with intestinal diseases. The result of discussion: There are three antimicrobial drugs most commonly implicated in infection with C.difficile, clindamycin, ampicillin and the cephalosporin. First-line antimicrobial drugs for C. difficile treatment are metronidazole and vancomycin; however, recent data suggest that metronidazole is losing its efficacy and expert suggests to use more radical methods for treatment such as transplant of fecal microbiota. Transplantation can be provided through a variety of methodologies, either to the lower proximal, lower distal, or upper gastrointestinal tract. A research conducted in 2008 by T. Brodie, an Australian gastroenterologist, and other scientists, allowed to extend the list of indications for TFM. In addition to the treatment of intestine pathologies, faecal transplant was used to treat diseases like Parkinson's disease, diabetes mellitus, and insulin resistance, rheumatoid arthritis, obesity, and multiple sclerosis. Conclusion: Unfortunately C.difficile infection increases incidence, severity and recurrence rates, particularly in the last several years. From 1996 to 2010, the reported incidence of CDI cases in acute care hospitals in the U.S indicates an increase from 139,000 to 349,000. Up to now the intestinal microbiota has been generally inaccessible to scientific researches because most of them were hardly cultivated in the laboratory. The transplant of fecal microbiota proves to be an inexpensive and very effective intervention in intestinal diseases treatment. According to literature data, about 90% of patients are cured, so this procedure represented a real success in modern medicine. Key-words: Fecal microbiota, Clostridium difficile, recurent infection, intestinal disease

Cob, a vernacular earth construction process in the context of modern sustainable building

The will of reducing environmental and social impact of building industry has led to a renewed interest in earth construction. Most of earth construction literature dealt with rammed earth or adobe techniques, but very little with cob. Yet, cob participates in the diversity of vernacular earth construction processes that value local materials and is an alternative to rammed earth and adobe in specific geographical conditions. Conservation of cob heritage also requires a better knowledge of this vernacular construction process. This bibliographical analysis gathered extensive data on cob process and summarized the different cob process variations, attempting to take into account their diversity. This analysis allowed us to provide novel data on cob process, and more specifically, (1) a clear definition of cob with regard to other earth construction processes, (2) a first summarized description of cob process that clearly distinguished its variations, (3) a list of fibres traditionally employed, (4) values and, if possible, average and standard deviation for fibre length, fibre content, manufacture water content, drying times, lift heights and wall thicknesses, (5) a summary of the strategies to manage shrinkage cracks, (6) a criterion on the quality of implementation and/or earth for cob, based on slenderness ration of lifts and (7) a discussion on the evolution of cob process with regard to societal evolutions

THE IMPORTANCE OF VACCINATION

Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu”, Chişinău, Republica MoldovaIntroducere. Vaccinarea este una dintre cele mai eficiente modalități de combatere a bolilor infecțioase. Datorită vaccinurilor, putem preveni dezvoltarea infecțiilor periculoase și severe, ne putem proteja corpul de posibile complicații și putem salva vieți. Vaccinarea este un măsură de precauție, importantă nu numai pentru sănătatea personală, ci și pentru securitatea națională, deoarece ajută la prevenirea epidemiilor și răspândirea infecțiilor periculoase. Scopul lucrării. Identificarea avantajelor și dezavantajelor vaccinării, determinând efectul acesteia asupra organismului uman. Specificarea factorilor care contribuie la micșorarea riscului de expunere la infecții și rolul protejării indirecte a persoanelor nevaccinate din comunitate. Materiale și metode. Cercetarea a fost realizată pe baza documentelor, analizelor statisticile mondiale privind vaccinarea, monitorizarea eficacității, siguranței și efectelor pe termen lung ale vaccinurilor. Rezultate. Vaccinarea este deosebit de importantă în prevenirea și controlul bolilor infecțioase. Iată câteva rezultate-cheie ale vaccinării: 1) Prevenirea bolilor: Vaccinurile sunt concepute pentru a stimula sistemul imunitar să recunoască și să lupte împotriva agenților patogeni care cauzează diferite boli. Prin vaccinare, se poate preveni apariția bolilor infecto-contagioase grave, cum ar fi: poliomielita, rujeola, tetanosul, varicela, hepatita B și multe altele. 2) Vaccinarea în masă a populației poate reduce semnificativ rata de îmbolnăvire și, în cele din urmă, poate eradica complet unele boli. Un exemplu notabil este vaccinul împotriva variolei, care a dus la dispariția bolii în întreaga lume. 3) Vaccinurile pot ajuta la prevenirea complicațiilor severe ale bolilor infecțioase și pot salva vieți. 4) Acestea pot reduce riscul de dezvoltare a complicațiilor grave, cum ar fi pneumonia, meningita, encefalita și afecțiunile cronice asociate cu anumite boli. Concluzii. Prin vaccinare, putem controla și eradia anumite boli infecțioase, protejăm persoanele vulnerabile și asigurăm sănătatea comunității în ansamblu. Prin urmare, este esențial să promovăm și să susținem vaccinarea pentru a construi un viitor mai sănătos și mai sigur.Introduction. Vaccination is one of the most effective ways to fight infectious diseases. Thanks to vaccines, we can prevent the progression of dangerous and severe infections, protect our bodies from possible complications and save lives. Vaccination is an important thing not only for personal health, but also for public safety, as it prevents epidemics and the spread of dangerous infections. The purpose of the work is to identify the advantages and disadvantages of vaccination, to determine the effect of vaccination on the human body, to demonstrate the risk reduction of exposure to an infection and the role of indirect protection of unvaccinated people in the society. Materials and methods. The research was based on science researches, analysis of world’s vaccination statistics, monitoring the effectiveness, safety and long-term effects of vaccines. Results. Vaccination is particularly important in the prevention and control of infectious diseases. Here are the main benefits of vaccination: 1) Disease prevention: Vaccines help the immune system recognize and fight pathogens that cause various diseases. Vaccination can prevent serious infectious diseases such as polio, measles, tetanus, chicken pox, hepatitis B and many others. 2) Mass vaccination of the population can significantly reduce the incidence of disease and eventually eradicate some diseases completely. A good example is the smallpox vaccine, which led to the eradication of the disease worldwide. 3) Vaccines help prevent severe complications of infectious diseases and save lives. 4) They can reduce the risk of developing serious complications such as pneumonia, meningitis, encephalitis and other chronic conditions associated with certain diseases. Conclusions. We can assume that through vaccination people can control and eradicate certain infectious diseases, protect population and ensure health of the society as a whole. Therefore, it is essential to promote and support vaccination to build a healthier and safer future

A new methodology to identify and quantify material resource at a large scale for earth construction – Application to cob in Brittany

A new methodology based on the cross-referencing of spatialized pedological and heritage data is proposed to identify and quantify soil resources available for earth construction. The paper underlines the pedological particularities of areas containing earth heritage and uses these particularities to propose criteria to assess the suitability of soils for modern earth construction. The methodology applied at the regional scale in France (for a given area of 27,200 km2 in Brittany) enabled to specify five new texture classes (balance between clay, silt, sand and gravel content) of suitability for cob soils. This result calls into question recommendations available in the literature. The methodology also provides data on the scale of availability of the resource to repair earth built heritage (cob) or to build new low impact buildings with integrated modern cob walls. In the studied area the potential waste recovery of 2.8 Mt per year is measured, highlighting the large availability of materials for earth construction. At least 23% of earthwork wastes of Brittany are suitable for earth construction (0.7 Mt). However, earth remains a non-renewable material and this resource has to be properly managed, requiring an appropriate building design and maintenance in order to increase longevity and to avoid the use of admixture, preventing earth reversibility at end of life

Adsorption and recovery of phosphate from aqueous solution by the construction and demolition wastes sludge and its potential use as phosphate-based fertiliser

This study aimed to investigate phosphate removal from aqueous effluents by an inorganic sludge from the inert part of construction and demolition wastes (CSW) as adsorbent. It is also discussed the application of the loaded P adsorbent as potential fertiliser. The CSW was also thermally treated at 800¿°C for 2¿h (CSW-T), and its influence in the P removal was also investigated. The characterisation techniques highlighted low porosity on CSW and CSW-T adsorbents and that they are mainly formed by oxides which could enhance the P uptake and recovery. In pH experiments, P adsorption increased as initial pH increased, at pH higher than 7.8 the P removal sharply increased due to the formation of calcium phosphate precipitate. The mechanism of the P adsorption onto CSW indicated that the process was mainly controlled by chemical bonding or chemisorption. The results showed that CSW-T was more effective for P removal in comparison to CSW based on the Liu isotherm, the maximum sorption capacity attained was 24.04 (CSW) and 57.64¿mg¿g-1 (CSW-T). Based on the Avrami’s kinetic models, the time for attaining 95% of saturation was 212.6 (CSW), and 136.6¿min (CSW-T). CSW and CSW-T showed the highest phosphate-removal performance among many adsorbents found in the literature; therefore, this kind of waste can be used widely as an inexpensive phosphate-recovery adsorbent. Besides, the P loaded adsorbents could be used as potential fertilisers which could be an interesting and efficient way of reuse for this waste.Peer ReviewedPostprint (published version

Current Applications of Recycled Aggregates from Construction and Demolition: A Review

A literature review comprising 163 publications published over a period of 26 years from 1992 to 2018 is presented in this paper. This review discusses the generation and recycling of construction and demolition waste (CDW) as well as its main uses as raw materials for the construction engineering sector. This review pays attention to the use of CDW aggregates for sand, pavements/roads, bricks, ceramics, cementitious materials, and concrete productions, as well its uses as eco-friendly materials for water decontamination. The physical-chemical and mechanical characteristics of recycled aggregates play an important role in their correctly chosen applications. The results found in this literature survey allow us to conclude that recycled aggregates from CDW can be successfully used to produce construction materials with quality comparable to those produced with natural aggregates. We concluded that the use of CDWs as raw materials for manufacturing new construction materials is technically feasible, economical, and constitutes an environmentally friendly approach for a future construction and demolition waste management strategy

A sorting method to value recycled concrete

The purpose of this paper is to propose a sorting platform to increase the quality of recycled aggregates through the supplementary use of mineral processing techniques and additional sorting. The difficulty of liberation is discussed, and the methodology currently used in mineral processing is proposed. Jigs, hydrocyclones and sensor-based sorting are considered to have good performance in the sorting of adequately recycled aggregates. The new perspectives on sorting and liberation for recycling aggregates are discussed. The new process is presented based on the current process in recycling platforms, with supplementary sorting of the recycled concrete. The gain in density and the reduction in water absorption are studied. The relation between the water content and the density of aggregates is analysed for three quality levels of recycled aggregates. The gain in density and the reduction in water absorption were linked to the aggregate replacement rates. The reduction in transport and discharge costs due to the increased aggregate quality was linked to the aggregate replacement rate and distance to quarry. In our study, replacing a lower-quality aggregate with another of medium quality leads to an expected density gain of approximately 4%. Conversely, if replaced by superior quality aggregate, the expected gain will be 8.4%. As a consequence, a 34% reduction in water absorption could also be obtained. The cost reduction is exponential with the substitution rate of recycled materials. There is a decrease in transport costs if the quality of recycled aggregates increases. Conversely, if the reduction in transport costs when the quality of recycled aggregates increases is considered, the distance between the demolition site and quarry is not important