51 research outputs found
Exploration of ceramic clays in the countryside of Córdoba (Spain)
El presente trabajo trata de la exploración de arcillas con baja proporción de calcita, en el sur de la provincia de Córdoba,
para suministrar materias primas a la fabricación de bloques y productos cerámicos. Para la caracterización del subsuelo se
han planificado tres zonas de trabajo de 4 km² cada una, en las que se han aplicado métodos geofísicos basados en perfiles de
Tomografía Eléctrica y Sondeos Eléctricos Verticales (SEV). En muestras de cada zona se han realizado análisis mineralógicos
de difracción de rayos-X (DRX), análisis químico por energías dispersivas de rayos-X (EDAX), ensayos de plasticidad, corte
directo, compactación, hinchamiento y capacidad portante, molienda, secado y cocción. Se ha conseguido descubrir, en estas
zonas, las áreas de interés para la explotación de materias primas, y con los resultados de esta prospección pueden estudiarse
nuevos yacimientos de arcilla cerámica.This paper deals with some aspects of the mining prospection of clays in the South of Córdoba (Spain). That studied clays are
used as raw materials in a processing plant of ceramic products. In this ground characterisation for future mining operations,
low proportion of carbonated materials was searched. To carry out the study, three seek areas were defined, each one of them
of about 4 Km2, where two geophysical methods were applied (Electrical Resistivity Tomography and Vertical Electrical
Sounding). X-ray diffraction, EDAX, direct cut, compaction, swelling and bearing capacity tests, among others, were carried
out in samples picked up in each seek area. Using the information provided by all these tests the most interesting areas for
the exploitation defined. These studies resulted in the selection of new interesting deposits for the clay industry
Recommendations for the Management of Construction and Demolition Waste in Treatment Plants
Construction and demolition waste consists approximately of one third waste generated
in the European Union. The recycling of this stream waste will provide ecological and sustainable
benefits. Recycled aggregates from construction and demolition waste are clearing a path into civil
constructions, as substitutes for natural aggregates. The possible applications of recycled aggregates
on infrastructure construction projects will depend on the quality of the recycled aggregates mainly.
This will be determined by the nature and the origin of the construction and demolition waste, and
the treatment system undergone. Hence, this work proposes recommendations for the handling of
construction and demolition waste in treatment plants
Characterizing of steel used in the construction of civil works in Almería
Se realizaron varios ensayos sobre las barras de acero utilizadas en la construcción de obra
civil en Almería, durante el período comprendido entre 18/1/2000 y 7/05/2001, con el fin
de caracterizar, mecánicamente, los diferentes tipos de aceros (soldables: B400S, B500S y
soldable dúctil: B400SD) y, de esta fonua, determinar si existe alguna razón técnica para un
incremento del consumo del acero soldable dúctil. Para ello, se ensayaron a tracción todas
las muestras que llegaron al laboratorio, siguiendo las normas UNE 7474-1: 1992 y UNE
7474-2:1992. Los resultados indican que el acero B400SD cumple, sólo, en un 86 % los
límites especificados en la norma UNE 36065:1999 -EX, frente al 95 y 94 % de los aceros
B400S y B500S. Además, el acero soldable dúctil muestra unos valores medios inferiores al
B400S. Este hecho discrepa de lo que se podría esperar según la norma que lo regulaVarious tests have be en conducted on the steel bars used in the construction of civil works
in Almería (Spain) during the period 18 ]anuary 2000-7 May 2001, with the aim of
mechanically characterizing the different types of steel (weldable: B400S, B500S and
ductile weldable: B400SD) to determine whether there is a technical reason for the
increase in the use of ductile weldable steel. For this, we have used a hydraulic machine to
break by traction all the test samples that arrived to the laboratory, following the
specifications of the UNE 7474-1:1992 and the UNE 7474-2:1992. The results indicate
that only in 86 % of the cases does the steel B400SD satisfy the limits specified by the UNE
36065:1999-EX, as opposed to 95 and 94 % of the B400S and B500S steels. In addition,
the ductile weldable steel registered mean values lower than those of B400S. This finding
disagrees with expectations set by the specifications
Photocatalytic Recycled Mortars: Circular Economy as a Solution for Decontamination
The circular economy is an economic model of production and consumption that involves reusing, repairing, refurbishing, and recycling materials after their service life. The use of waste as secondary raw materials is one of the actions to establish this model. Construction and demolition waste (CDW) constitute one of the most important waste streams in Europe due to its high production rate per capita. Aggregates from these recycling operations are usually used in products with low mechanical requirements in the construction sector. In addition, the incorporation of photocatalytic materials in construction has emerged as a promising technology to develop products with special properties such as air decontamination. This research aims to study the decontaminating behavior of mortars manufactured with the maximum amount of mixed recycled sand without affecting their mechanical properties or durability. For this, two families of mortars were produced, one consisting of traditional Portland cement and the other of photocatalytic cement, each with four replacement rates of natural sand by mixed recycled sand from CDW. Mechanical and durability properties, as well as decontaminating capacity, were evaluated for these mortars. The results show adequate mechanical behavior, despite the incorporation of mixed recycled sand, and improved decontaminating capacity by means of NOx reduction capacity
Catalogue of Pavements with Recycled Aggregates from Construction and Demolition Waste
Construction and Demolition Waste come from debris generated during construction, renovation and demolition of buildings, roads, and bridges. Recycling and reuse are essential in terms of sustainability, mainly from an environmental point of view. Although the recommendation of the use of these recycled aggregates is currently included in some technical specifications, its use is still not widespread due mainly to the lack of knowledge on their technical application. This work is a compilation of the recommendations proposed in the “Catalogue of road pavements with recycled aggregates”, supported by the construction of experimental stretches. It proposes different structural sections for road pavements by using recycled aggregates
Mechanical Performance of Concrete Made with the Addition of Recycled Macro Plastic Fibres
For many decades, researchers have been working on finding innovative and sustainable solutions to address the enormous quantities of plastic waste that are produced every year which, after being collected, are transformed into energy, recycled, or sent to landfills. Giving a second life to plastic waste as a material to be incorporated, in the form of macro-fibres, into concrete, could be one such solution. The purpose of this study was to analyse the mechanical and physical behaviour of the hardened concrete reinforced with macro plastic fibres (RPFs) obtained from food packaging waste (FPW) discarded during the packaging phase. By varying the quantity of macro-fibres used, physical and mechanical properties such as compressive strength, modulus of elasticity, flexural strength, and toughness were evaluated. It was observed that, although the presence of macro plastic fibres reduced the mechanical resistance capacity compared to that of traditional concrete, their contribution proved to be of some importance in terms of toughness, bringing an improvement in the post-crack resistance of the composite material. This innovative mixture provides a further impulse to the circular economy
A comparative study of recycled aggregates from concrete and mixed debris as material for unbound road sub-base
Siete áridos reciclados de residuos de construcción y
demolición (RCD) se han evaluado como zahorras para la
construcción de sub-bases de carreteras. Los resultados
muestran que los áridos reciclados de hormigón cumplen
todas las especificaciones del Pliego de Prescripciones
Técnicas Generales para Obras de Carreteras de España
(PG-3) para su uso en capas estructurales (sub-base) de
las categorías de tráfico T3 y T4. Algunos áridos reciclados
mixtos no cumplen por escaso margen algunas de
las especificaciones, debido a un alto contenido de compuestos
de azufre y a una menor resistencia a la fragmentación.
El precribado de la fracción fina antes de la
trituración de los RCD mixtos reduce el contenido de
azufre total y mejora la calidad, por el contrario, el precribado
de los RCD de hormigón no tiene ningún efecto
sobre la calidad de los áridos reciclados. Los resultados
se compararon con una zahorra artificial caliza como árido
naturalSeven different types of recycled aggregates from
construction and demolition waste (CDW) have been
evaluated as granular materials for unbound road subbases
construction. The results showed that recycled
concrete aggregates complied with all specifications for
using in the construction of unbound structural layers
(sub-base) for T3 and T4 traffic categories according to
the Spanish General Technical Specification for Road
Construction (PG-3). Some mixed recycled aggregates
fell short of some specifications due to a high content of
sulphur compounds and poor fragmentation resistance.
Sieving off the fine fraction prior to crushing the mixed
CDW reduce the total sulphur content and improve the
quality of the mixed recycled aggregates, by contrast,
pre-sieving concrete CDW had no effect on the quality of
the resulting aggregates. The results were compared
with a crushed limestone as natural aggregate
Feasibility of Using Unbound Mixed Recycled Aggregates from CDW over Expansive Clay Subgrade in Unpaved Rural Roads
Social awareness aims to increase practical skills, such as sustainable development, which
seeks to increase the use of different types of waste in construction activities. Although insufficient
attention is sometimes given to these actions, it is essential to spread information regarding new
studies in the field of waste recycling, which encourages and promotes waste use. Reusing and
recycling construction waste in the creation of buildings and infrastructure are fundamental strategies
to achieving sustainability in the construction and engineering sectors. In this context, the concept
of waste would no longer exist, as waste would become a material resource. Therefore, this study
analyses the behaviours of two unbound mixed recycled aggregates (MRA) in the structural layers of
an unpaved rural road with low traffic (category T43). The sections were built on inappropriate soil
(A-7-6) with a high degree of free swelling. The experimental road consisted of three sections: the
first was made with natural aggregates (NA) that were used as a control, the second was composed
of MRA in the subbase and NA in the base, and the third section was completely composed of MRA.
The materials were characterised in the laboratory. The behaviours of the structural layers in the
experimental road were determined by controlling compaction (“in situ” density and moisture) and
measuring the deflections and load capacity (deflectometer) during the 18 months after construction.
The results show that the sections made with recycled aggregates meet the technical specifications
required by General Technical Specifications for Road and Bridge Works (PG-3). Therefore, the
water-soluble sulphate content and Los Angeles abrasion coefficient limits can be increased for
recycled aggregates without compromising the quality of this type of road with low traffic. To the best
of our knowledge, this is the first study regarding the use of unbound MRA made from construction
and demolition waste (CDW) in the construction of an unpaved rural road with low traffic on an
expansive clay subgrade
Caracterización y posibilidades de reutilización en obras de infraestructura de los RCD's procedentes de la demolición de la prisión provincial de Córdoba
Comunicación presentada al III Congreso de Ingeniería Civil, Territorio y Medio Ambiente, Zaragoza, 2006El presente trabajo ha permitido la caracterización de los residuos de construcción y demolición (RCD’s) procedentes del derribo de la cimentación de la antigua Prisión Provincial de Córdoba. Tras una trituración primaria y secundaria, los materiales son sometidos a una trituración con molino de impactos que reduce el material a granulometrías inferiores a 50 mm, posteriormente el material es transportado hasta una criba vibrante de dos tamices que permite obtener tres fracciones de árido reciclado: 0-10 mm, 10-40 mm y mayor de 40 mm.
Para la identificación de cada una de las fracciones se han realizado ensayos en laboratorio de granulometría, plasticidad, contenido en materia orgánica, contenido en sales y yesos, hinchamiento y colapso. Para caracterizar su comportamiento se han realizado principalmente ensayos Proctor e índice C.B.R. Los resultados obtenidos han puesto de manifiesto su excelente comportamiento mecánico y su elevada capacidad de soporte, sin embargo de acuerdo con el contenido en sales solubles y yesos el material se clasifica como suelo tolerable según el Pliego de Prescripciones Técnicas Generales para Obras de Carreteras y Puentes (PG-3). El árido reciclado 10-40 mm no cumple las condiciones granulométricas para su utilización en rellenos tipo terraplén según el PG-3, y se propone continuar la investigación realizando mezclas a distintos porcentajes de las fracciones 0-10 mm y 10-40 mm
Assessment of response of greenhouse foundations to traction, and their simulation ussing finite elements
La causa de colapso de las estructuras de invernaderos son
las succiones provocadas por el viento. Actualmente no se
calculan las cimentaciones sometidas a esluerzos de tracción
yes la experiencia de los técnicos de las empresas
constructoras, o el deseo de los agricultores. lo que
determina las dimensiones y distancia entre el/as. En este
trabajo. se han ensayado prototipos a escala real de los
distintos tipos de pilotes usados en la construcción de
invernaderos. determinando laluerza máxima de tracción y el
desplazamiento asociado a la misma que pueden soportar. En
este artículo. se desarrollan modelos no lineales mediante el
método de elementos finitos. que permiten el cálculo de este
tipo de cimentaciones con mayor aproximación a los
resultados reales que el obtenido mediante el uso delórmulas
empíricas.rhe cause 01the col/apse 01the structures 01greenhouses is
the suction induced by wind. Currently, the design olthe
loundations is not based on calculations oltraction. rhe
experience 01the construction company or 01thelarmer
determine the dimensions and separation 01greenhouse
loundations. In this work. we tested prototypes 01diflerent
types olpileloundations. used in the construction 01
greenhouse, to determine the maximumlorce 01 traction and
the associated displacement which they can support. In this
article. non-linear models using finite elements. are
developed that enable more accurate calculation olthe
actual results than obtained with empiricallormulas
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