Papers by Leticia Lescano
Polymer Engineering & Science
En el presente trabajo se analizó la biosedimentación y la mineralogía de los sedimentos intermar... more En el presente trabajo se analizó la biosedimentación y la mineralogía de los sedimentos intermareales de dos sitios del estuario de Bahía Blanca, y su relación con las especies vegetales y la dinámica poblacional de Neohelice granulata. Se trazaron dos transectas perpendiculares al submareal; la trasecta A en Puerto Cuatreros y la B en Villa del Mar. Los muestreos se realizaron de marzo a junio de 2013. En cada transecta se seleccionaron dos estaciones, en las cuales se recolectaron sedimentos superficiales (control) y sedimentos removidos por cangrejos que fueron examinados teniendo en cuenta un enfoque ambiental, textural y mineralógico. Se estimó la densidad de cuevas, la cobertura vegetal y paralelamente se registraron datos ambientales. Para la caracterización granulométrica y mineralógica de arcillas se efectuaron estudios con el método de grano suelto bajo lupa y de difracción por rayos X, empleando métodos estandarizados de laboratorio. Los resultados de los difractogramas ...
Revista de Geología Aplicada a la Ingeniería y al Ambiente, 2019
La ex usina general San Martin, fue construida en la decada del 30 para proveer de energia elect... more La ex usina general San Martin, fue construida en la decada del 30 para proveer de energia electrica a la ciudad de Bahia Blanca. Fue desafectada de sus servicios en 1987, y su desguace comenzo en 1997. Su estructura edilicia muestra deterioros significativos, sin embargo el principal interes ambiental dentro de este edificio es la presencia de materiales asbestiformes. por lo que deberan tomarse medidas precautorias al momento de la puesta en valor. Se localiza en un sector densamente poblado (en el puerto de Ing. White), negativo a efectos ambientales debido que las fibras de asbestos al ser livianas se esparcen facilmente por largas distancias.Con el objeto de identificar los materiales que contienen asbestos, se tomaron muestras del piso (baldosas y alisado de cemento), paredes, columnas, bloques caidos de los techos (fibrocemento) y tuberias. Para la identificacion y caracterizacion de los minerales asbestiformes, se utilizo estereomicroscopio, microscopio petrografico, di...
IAEG/AEG Annual Meeting Proceedings, San Francisco, California, 2018 - Volume 2, 2018
In Argentina, asbestos is associated with meta-mafic or meta-ultramafic igneous rocks, mainly ser... more In Argentina, asbestos is associated with meta-mafic or meta-ultramafic igneous rocks, mainly serpentinites (or steatized varieties) and amphibolites, and less commonly with dolomitic rocks (in metamorphic and metasomatic domains). Chrysotile, anthophyllite and tremoliteactinolite were identified as the main asbestiform minerals (in the range of respirable particles). Chrysotile occurs mainly in serpentinites or steatized rocks as well as in amphibolites and other host rocks nearby. It appears filling veins, as slip and cross-fiber, generally associated with fissures or shear zones. Amphibole asbestos, mainly from the tremolite-actinolite series and anthophyllite, commonly occurs together with a non-asbestiform coun terpart within the same area and deposits. These minerals have been found in talc ores as well as in vermiculite-rich sectors, or filling fissures in meta-mafic and meta-ultramafic rocks. In this compilation, the results of case studies on mines from the provinces of Cordoba, Mendoza and San Juan (Argentina) are summarized, and
Las arenas naturales utilizadas como agregado fino en ei sur de la provincia de Buenos Aires está... more Las arenas naturales utilizadas como agregado fino en ei sur de la provincia de Buenos Aires están constituidas predominantemente por rocas volcánicas (hasta un 46%), de las cuales, un gran porcentaje presenta pastas vitreas (frescas y alteradas). Es frecuente también la presencia de trizas de vidria volcánico y en menor medida de calcedonia. Estos componentes, pueden provocar reacciones deletéreas cuando son utilizados en hormigones con contenidos considerables de álcali y exposición constante a períodos de humedad. En el presente trabajo se relevaron y maestrearon nueve canteras comercialmente activas ubicadas en proximidades de las localidades de Claromecó, Orense, Necochea, Médanos, Villalonga y Río Colorado. Se realizó un análisis granulométrico según norma IRAM 1627y el correspondiente estudio petrográfico según lo establecida en la norma IRAM 1649.Se analizó la composición modal en cada fracción y se determinaron las especies potencialmente reactivas frente a la reacción álcali - sílice en el hormigón según las especificaciones de la norma IRAM 1512
El trabajo de investigación que desarrollo posee un gran interés para la provincia, ya que la con... more El trabajo de investigación que desarrollo posee un gran interés para la provincia, ya que la contaminación ambiental con asbestos es un tema que afecta directamente a la salud de la población. En nuestro país los asbestos se encuentran prohibidos desde el año 2000 por resolución del Ministerio de Salud (845/00 y 823/01), es por esto que es necesario estudiar los materiales que pueden contener estos minerales en edificios antiguos, para tomar los recaudos necesarios al momento de realizar reparaciones, demoliciones y/o reemplazos por otros materiales. Me he doctorado en esta temática “Asbestos Argentinos” y he realizado numerosas publicaciones tanto en revistas nacionales como internacionales. A su vez, en la actualidad realizo numerosos trabajos de control ambiental para empresas públicas y privadas, poniendo énfasis en la determinación de minerales nocivos para la salud
El edificio central de la Usina Gral. San Martín, declarado Monumento Histórico Nacional, fue con... more El edificio central de la Usina Gral. San Martín, declarado Monumento Histórico Nacional, fue construido a mediados de la década del 30’ en el puerto Ingeniero White de la ciudad de Bahía Blanca (Argentina), y presenta un significativo deterioro como consecuencia del desmantelamiento y el natural paso del tiempo. En este trabajo se evaluó el estado de conservación de algunos materiales que se utilizaron en la construcción del edificio, el desarrollo de diferentes manifestaciones patológicas y se analizó la presencia de materiales perjudiciales para la salud identificados en trabajos previos. Los resultados de los ensayos físicos y mecánicos indican que la elección de los materiales y el proyecto de las mezclas fue el adecuado para la estructura. Se determinó la procedencia de los agregados gruesos y finos, por lo que sería factible la elaboración de hormigones y morteros similares a los de la estructura original para los trabajos de remediación. Se identificaron minerales asbestifor...
La Belgica mine is located on the eastern flank of the sierra de Comechingones, in the department... more La Belgica mine is located on the eastern flank of the sierra de Comechingones, in the department of Calamuchita (Cordoba province). It is emplaced in a serpentinitic body of the western ultamafic belt of the Sierras Pampeanas de Cordoba. In this work, the serpentinitic rocks of La Belgica mine were studied, with special emphasis on chrysotile, the only asbestiform polymorph of the serpentine group. Chrysotile is developed in veinlets within the serpentine rock, in fractures and shear zones. The habit is fibrous and the crystals grow perpendicularly to the walls of the fracture ( cross-fiber asbestos). Samples from the veins and the serpentinite were taken and studied by optical microscopy, X-ray diffraction, chemical analysis, SEM-EDS and thermal analysis TG-DTA. On thin sections, cross and slip fibers as well as asbestiform veinlets show a variable crystalline growth. Frequently, cuts and replacements between these veinlets and fiber microstructures indicate that they were formed ...
Lightweight concrete has a lower unit weight than conventional concrete and a high thermal insula... more Lightweight concrete has a lower unit weight than conventional concrete and a high thermal insulation capacity. It is manufactured with either natural or artificial lightweight aggregates. Vermiculite, one of the natural lightweight aggregates used, is a micaceous material that when heated increases its original volume due to an exfoliation process, so its incorporation in concrete or mortar imparts very low density. These natural materials usually contain impurities such as asbestiform minerals that can be released during the expansion process, causing a harmful environmental effect. Commercial asbestos-containing materials are currently banned due to the asbestos-related lung diseases they cause. In the province of Córdoba, Argentina, there are vermiculite mines where impurities such as asbestos group minerals have been identified. Studies using stereomicroscope, petrographic microscope, XRD, SEM, DTA and chemical analyses were conducted to characterize the different types of asbestos present and determine their particle size to assess whether they could be harmful to human health. Mica group minerals, abundant quartz and amphiboles were identified. The latter occur as isolated green crystals and their average length is 900 µm. Tremolite was determined by XRD. The aim of the present work is to reveal the presence of these minerals and warn about their use and disposal at the end of the useful service life of the work.
Argentina is a vast territory with different geological settings. In this scenery, dolomitic rock... more Argentina is a vast territory with different geological settings. In this scenery, dolomitic rocks are abundant and widespread. The economic importance of both this lithology and the main mineral constituent (dolomite) is the first cause for the studies carried out on these types of rocks. Dolomitic rocks in Argentina have been exploited for hundreds of years for different purposes. They are used as refractories, concrete aggregates and mastics, among other applications. Marble processing varies depending on its use and could include chemical treatments, burning, crushing, milling, and polishing. More impure marbles are crushed and used for construction, or discarded in spoil heaps in quarries. This chapter describes the mineralogical characteristics, textures, origin, mineral assemblages, and application of some dolostones, calcitic dolostones, dolomitic limestones, and marbles from the provinces of Buenos Aires, Río Negro and Córdoba (Argentina). The origin of these rocks varies even in close areas. In the province of Río Negro there are several deposits. One of them is composed of a dolostone formed from a preexisting hydrothermal limestone by circulation of hypersaline fluids rich in Mg and Na. It is a porous fine-grained (10 to 30 µm) rock consisting of dolomite with minor amounts of quartz, feldspar, and rhyolite particles. Clay minerals (montmorillonite, illite and sepiolite) were also identified. The alkali-carbonate reactivity of this rock when used as concrete aggregate has been analyzed. Another deposit is composed of a dolomitic marble generated by the metamorphism of a preexisting dolostone. The only mineral present is dolomite, but the further circulation of hydrothermal fluids in cracks developed talc veins with a sepiolite + calcite + amphibole (tremolite) assemblage. The main use of brought to you by CORE View metadata, citation and similar papers at core.ac.uk
La Judita mine is located at 70 Km NE of Uspallata, in the province of Mendoza, cióse to San Juan... more La Judita mine is located at 70 Km NE of Uspallata, in the province of Mendoza, cióse to San Juan limit. The outerops are irregular bodies elongated N-S, of small dimensions (with a length not exceeding 500 meters), emplaced on the western flank of the Precordillera. The main work is a quarry from which 500 tons m3 of material was extracted, constituted by tale with minor amount of chlorite, tremolite, calcite and iron oxides and hidroxides. Steatized sector, serpentini- zed altered zone and the chloritic schist (country rock of intrusive) were analyzed. Two polymorphs of serpentine were identified: antigorite (the main mineral developed during the serpentinization of the ultramafic rock) and chry- sotile in veins with irregular distribution. In the intensely altered zone, it was observed that tale is cióse related with chlorite, calcite and iron oxides. In the tale ore asbestiform morphologies were not distinguished, although in the serpentinitic bodies, cióse to the mine, chrysotile veins were recognize
La mina La Isla se localiza a 2,5 Km al sur de la localidad de José de la Quintana, en el departa... more La mina La Isla se localiza a 2,5 Km al sur de la localidad de José de la Quintana, en el departamento Santa María de la provincia de Córdoba (Argentina). Sus coordenadas son 31o49’30.6”S y 64o24’53”O (Figura 1a). La región presenta afloramientos del Complejo Metamórfico La Falda, compuesto por gneises biotíticosmuscovíticos bandeados (79 %) con intercalaciones de ortogneises leucotonalíticos (9 %), mármoles dolomíticos (8 %), anfibolitas y rocas calcosilicáticas (3 %) (Lucero Michaut et al. 2000). Este basamento aparece intruído por diques basálticos de edad cretácica (> 1%) similares a los descriptos por Gordillo y Lencinas (1969). Los antecedentes sobre este yacimiento son escasos, sólo pueden citarse los trabajos de Viltes (2011) que describe la geología del depósito y el de Lescano et al. (2012) sobre la mina Soledad, perteneciente al mismo distrito minero. Los trabajos mineros realizados, consistentes en destapes y canteras a cielo abierto, han permitido observar cuerpos ul...
Evaluation o f the State o f conservaron o f concrete floors o f the city o f Bahía Blanca, (Buen... more Evaluation o f the State o f conservaron o f concrete floors o f the city o f Bahía Blanca, (Buenos Aires province). Pavements from Bahía Blanca city were evaluated. The area is delimitated by Maldonado channel and railway tracks. It was covered an area of 33 km2 where only 18.7 % of the pavements are made with concrete. The condition of the slabs (structural failure, surface abrasión, shrinkage cracks, fissures by alkali-silica reaction), the condition of contractionjoints (or the lack of them) and the type of aggregate used were analyzed. Slabs requiring total replacement and slabs cut for the provisión of public Services were also evaluated. In cases where possible, samples were taken, and porosity, absorption and density were determined. In addition, studies with stereomicroscope were carried out to characterize the fine and coarse aggregates, the State of the mortar, determining the presence of microcracks and neoformation producís. A statistical study was carried out on 15776 slabs, and it was concluded that 48.1% of them are damaged. Of this, 46.8% is due to structural failures, requiring a total replacement of 14%. It is common to observe surface abrasión in those with aggregates of greater size and especially, in the slabs of Street intersections. This is due to the abrasive effect of tralfic and inadequate drainage of rainwater that allows its accumulation on the pavement.
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Papers by Leticia Lescano