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

Feasibility of using olive biomass bottom ash in the sub-bases of roads and rural paths

Clay soils are widely distributed throughout the world and are the source of multiple technical problems in their application for the construction of sub-grade and sub-road bases. These types of soils are found in areas where civilian infrastructure such as roads and rural roads must be built. Therefore, in many situations it is necessary to use stabilized expansive soils, in the formation of the foundation and structural layers of linear infrastructures. Soil stabilization is used to increase the load capacity of the soil, and mixtures of lime and cement are generally used as binders. In recent years, interest in the recycling of industrial products and by-products has increased. One example of this is the use of biomass combustion in power plants. The management of significant amounts of waste (biomass bottom ash) from biomass power plants remains a problem. This paper presents the results of an experimental study for stabilizing expansive soil to determine its bearing capacity and mechanical properties via a triaxial test of the addition of biomass bottom ash. A double objective was targeted: reduction of the problems in using this type of soil and provision of a use for this type of waste. The results showed significant improvements in the mechanical. Therefore, herein is proposed the use of biomass bottom ash as a stabilizing agent for expansive soils, to improve the efficiency of the construction process by incorporating this product into a second life cycle as road bases

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

Mechanical performance of roller compacted concrete with recycled concrete aggregates

Because the recycling of construction and demolition waste (CDW) has been deemed to be a priority, the use of a recycled aggregate has been widely demonstrated as a sustainable contribution among different materials applied in civil projects. Roller compacted concrete applications (RCC) offer technical, economic and ecological solutions in many civil construction projects. To the best of the authors’ knowledge, there has been little research on the use of RCC with a coarse recycled aggregate that does not originate from pavement. This research evaluates the use of recycled concrete aggregates (RCA) from a CDW recycling plant in RCC mixtures. Four series of RCC mixtures were produced with different cement contents (110, 175, 250 and 350 kg/m3). Each series consisted of three mixtures with different RCA incorporation ratios (0%, 50% and 100%) of natural coarse aggregates, thus producing 12 RCC mixtures to evaluate the effect on the compaction, the mechanical and physical properties while highlighting a new laboratory casting method for flexural strength and drying shrinkage tests. Based on the obtained results, the use of coarse RCA in RCC production is feasible at a replacement level of 100% when using these materials in road pavement bases

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