APLICACIÓN AL ESTUDIO DE LA RESPUESTA MECÁNICA DE LA CAPA DE SUBBALASTO DE VÍAS FERROVIARIAS FORMADO POR UNA MEZCLA NO BITUMINOSA DE MATERIAL GRANULAR Y PARTÍCULAS PROCEDENTES DE NEUMÁTICOS FUERA DE USO

Tesis por compendioScrap tyres are a solid waste material which has been generated in large quantities over the last decades. In Spain, between 2000 and 2014 the number of vehicles increased by 30% and a further 3.5% increment is expected for the next fifteen years. Likewise, the number of scrap tyres is also expected to rise within the same order of magnitude. Taking into account the big volume of waste generated, proper disposal and reutilisation management is required, ever more so as scrap tyres are non-biodegradable. Moreover, if simply stockpiled in landfills, further environmental damage may be produced in case of fire as the fumes thus generated carry harmful carcinogenic particles. In order to deal with this problem, a Royal Decree (RD 1481/2001) was approved in July 16, 2006 which completely forbidden landfilling of scrap tyres. Later the same year another Royal Decree (RD 1619/2005) was issued to establish scrap tyres management in Spain. This decree requires reutilisation and recycling plans to be elaborated so as to fully eliminate waste derived from scrap tyres. Nowadays, among the reutilisation options more demanded are tyre remoulding, construction of sport pitches, artificial grass and playpens, and as combustible for cement factories. On the other hand, only 1% of scrap tyres are reused in infrastructure construction. Taking profit of the latest transport plans approved by the European Union, which aim to promote more efficient and environmentally friendly transport means such as railways, this PhD thesis proposes a new and promising alternative: to use rubber particles from scrap tyres as construction material, in the form of unbounded rubber-aggregate mixtures for subballast layers under railway tracks. This option offers two noteworthy environmental advantages. On the one hand, large quantities of a rather problematic and harmful waste material may be reused. On the other hand, the new mixtures proposed help to improve the low resistance to fragmentation of calcareous aggregates, thus allowing the use of such materials in the construction of railway tracks. The objective of this research is to obtain the optimum rubber content for the new mixtures to fulfil all the requirements of subballast layers. Moreover, taking into account the elastic properties of rubber, the potential attenuation of the vibration generated by passing rolling stock is also assessed. As a complementary research, rubber-natural soil mixtures are studied as well so as to evaluate their viability as construction material for embankment cores.El neumático fuera de uso es un residuo sólido que se está generando en grandes cantidades en las últimas décadas. En España, entre los años 2000 y 2014 el parque de vehículos se incrementó en un 30%, y se prevé un aumento del 3.5% para los próximos quince años. Estos datos ponen de manifiesto que el número de neumáticos fuera de uso se incrementará en el mismo orden. Dado el gran volumen de residuo generado, es necesario realizar una gestión de retirada y reutilización de este residuo, al tratarse de una material no biodegradable. Además representa una gran amenaza medioambiental si este residuo termina en vertederos incontrolados, ya que en caso de incineración, los humos que se desprenden arrastran partículas cancerígenas que pueden provocar problemas de salud. Para atajar este problema, el 16 de julio de 2006 entró en vigor el Real Decreto 1481/2001, por el que se prohíbe el depósito en vertedero. A finales de este mismo año también entró en vigor el Real Decreto 1619/2005, sobre la gestión de neumáticos fuera de uso en España, el cual establece que se elaboren planes de reutilización y reciclado para eliminar el total de los residuos derivados de los neumáticos de desecho. En la actualidad, entre las medidas de reutilización más demandadas está el recauchutado, la construcción de pistas deportivas y campos de césped artificial, parques infantiles, y como combustible para centrales de fabricación de cemento. En cambio, en el sector de la construcción se reutiliza menos del 1%. Aprovechando la predisposición de los últimos planes de transporte de la Unión Europea por promover aquellos modos de transporte más eficientes y respetuosos con el medioambiente, como es el ferrocarril, la presente Tesis Doctoral plantea una alternativa adicional y prometedora: el uso de partículas de caucho procedentes de la trituración de los neumáticos como material de construcción, en forma de mezclas de caucho con áridos sin ningún tipo de ligante para ser utilizado como capa de subbalasto en vías ferroviarias. Esta opción ofrece dos ventajas medioambientales importantes. Por un lado, permite la reutilización de grandes cantidades de este residuo considerado peligroso y problemático. Por otro lado, dicha mezcla contribuye a la mejora de la baja resistencia de fragmentación de los áridos calcáreos, pudiendo de esta manera ser reutilizados en capas de asiento en las vías ferroviarias. El objetivo de esta investigación se centra en la obtención del contenido óptimo de caucho para que el nuevo geomaterial cumpla los requerimientos para su uso como capa de subbalasto, y además, dadas las propiedades elásticas del caucho, evaluar el potencial de atenuación de las vibraciones que se generan al paso del tráfico ferroviario. Como investigación complementaria, se han realizado un estudio con mezclas de caucho y suelo natural para comprobar la viabilidad de utilización en núcleos de terraplén.El pneumàtic fora d'ús és un residu sòlid que s'està generant en grans quantitats en les últimes dècades. A Espanya, entre els anys 2000 i 2014 el parc de vehicles es va incrementar en un 30%, i es preveu un augment del 3.5% per als pròxims quinze anys. Estes dades posen de manifest que el nombre de pneumàtics fora d'ús s'incrementarà en el mateix orde. Donat el gran volum de residu generat, és necessari realitzar una gestió de retirada i reutilització d'este residu, al tractar-se d'una material no biodegradable. A més representa una gran amenaça mediambiental si este residu acaba en abocadors incontrolats, ja que en cas d'incineració, els fums que es desprenen arrosseguen partícules cancerígenes que poden provocar problemes de salut. Per a atallar este problema, el 16 de juliol de 2006 va entrar en vigor el Reial Decret 1481/2001, pel qual es prohibeix el depòsit en abocador. A finals d'este mateix any també va entrar en vigor el Reial Decret 1619/2005, sobre la gestió de pneumàtics fora d'ús a Espanya, el qual estableix que s'elaboren plans de reutilització i reciclatge per a eliminar el total dels residus derivats dels pneumàtics de rebuig. En l'actualitat, entre les mesures de reutilització més demandades està el recautxutatge, la construcció de pistes esportives i camps de gespa artificial, parcs infantils, i com a combustible per a centrals de fabricació de ciment. En canvi, en el sector de la construcció es reutilitza menys del 1%. Aprofitant la predisposició dels últims plans de transport de la Unió Europea per promoure aquells modes de transport més eficients i respectuosos amb el mediambient, com és el ferrocarril, la present Tesi Doctoral planteja una alternativa addicional i prometedora: l'ús de partícules de cautxú procedents de la trituració dels pneumàtics com a material de construcció, en forma de mescles de cautxú amb àrids sense cap tipus de lligant per a ser utilitzat com a capa de subbalast en vies ferroviàries. Esta opció ofereix dos avantatges mediambientals importants. D'una banda, permet la reutilització de grans quantitats d'este residu considerat perillós i problemàtic. D'altra banda, la dita mescla contribueix a la millora de la baixa resistència de fragmentació dels àrids calcaris, podent d'esta manera ser reutilitzats en capes d'assient en les vies ferroviàries. L'objectiu d'esta investigació es centra en l'obtenció del contingut òptim de cautxú perquè el nou geomaterial complisca els requeriments per al seu ús com a capa de subbalast, i a més, donades les propietats elàstiques del cautxú, avaluar el potencial d'atenuació de les vibracions que es generen al pas del tràfic ferroviari. Com a investigació complementària, s'han realitzat un estudi amb mescles de cautxú i sòl natural per a comprovar la viabilitat d'utilització en nuclis de terraplè.Hidalgo Signes, C. (2017). APLICACIÓN AL ESTUDIO DE LA RESPUESTA MECÁNICA DE LA CAPA DE SUBBALASTO DE VÍAS FERROVIARIAS FORMADO POR UNA MEZCLA NO BITUMINOSA DE MATERIAL GRANULAR Y PARTÍCULAS PROCEDENTES DE NEUMÁTICOS FUERA DE USO [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86140TESISCompendi

Determination of thermal conductivity variation through Modified Transient Plane Source (MTPS), and its relationship with porosity variation on thermally treated Prada limestone

In this research, the variation of thermal conductivity with temperature of a limestone and its relationship with porosity is studied. Samples from Prada formation, a lower Cretaceous limestone from the Catalan Pyrenees (Spain), obtained from the Tres Ponts road tunnel were subjected to temperatures of 105, 300, and 600 °C and then cooled at a slow rate by air-cooling to laboratory temperature. Open porosity tests were determined before and after heating to evaluate the porosity increase and the micro-cracks growth. Complementarity, thermal conductivity was measured in the rock samples before and after the application of a thermal treatment by means of C-Therm TCi device, a Modified Transient Plane Source (MTPS). This is a non-invasive, quick, and precise method, when compared with other steady-state laboratory alternatives, widely used to directly determine thermal properties of rock samples. A clear decrease in the thermal conductivity of above 10% was observed for samples heated at 600 °C, probably due to a dramatic increase in porosity. The obtained results could be of great interest for the incorporation of the effect of temperature on rock in numerical models, to evaluate the potential impacts induced by eventual fires developed inside the Tres Ponts tunnel.This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Analysis of the vibration alleviation of a new railway sub-ballast layer with waste tyre rubber

[EN] This paper focuses on the assessment of the vibration behaviour of granular sub-ballast materials mixed with rubber particles from scrap tyres. The main objective is to evaluate whether these mixes attenuate vibrations caused by passing trains, and if so, to what extent. Several laboratory and field tests were carried out to monitor the response of such materials to various excitation sources. The results show that under controlled laboratory conditions, the addition of rubber (up to 5% by weight) greatly increases the damping ratio and reduces vibration. Field tests also show that higher percentages of rubber yield a significant alleviation of vibration caused by repetitive and harmonic loads that are similar to those produced by passing trains. An addition of 5% by weight yields a reduction of 50% in the mean acceleration peak at one metre from the excitation source. The anisotropy of the mix is another key factor when evaluating the vibration behaviour of these mixes.The authors wish to thank GUEROLA for providing the soil samples from its quarry, EMRO for providing the rubber particles, and Ángel Morilla Rubio, Manolo Medel Perallo´n, and Esther Medel Colmenar for their help during field tests.Hidalgo Signes, C.; Martínez Fernández, P.; Medel Perallon, E.; Insa Franco, R. (2017). Analysis of the vibration alleviation of a new railway sub-ballast layer with waste tyre rubber. Materials and Structures. 50(2):1-13. doi:10.1617/s11527-016-0951-0S113502Yoon S, Prezzi M, Zia Siddiki N, Kim B (2005) Construction of a test embankment using a sand–tire shred mixture as fill material. Waste Manag 26:1033–1044Nakhaei A, Marandi SM, Sani Kermani S, Bagheripour MH (2012) Dynamic properties of granular soils mixed with granulated rubber. Soil Dyn Earthq Eng 43:124–132Buonanno A, Mele R (2012) The use of bituminous mix sub-ballast in the Italian state railways. 2nd eurasphalt and eurobitume congress, Barcelona, 20–22 September 2000Di Mino G, Di Liberto M, Maggiore C, Noto S (2012) A dynamic model of ballasted rail track with bituminous sub-ballast layer. Proced Soc Behav Sci 53:366–378Hidalgo C, Martínez P, Medel E, Insa R (2015) Characterisation of an unbound granular mixture with waste tyre rubber for subballast layers. Mater Struct 48:3847–3861. doi: 10.1617/s11527-014-0443-zThompson DJ (2009) Railway noise and vibration: mechanisms, modelling and means of control. Elsevier, OxfordAuersch L (2005) The excitation of ground vibration by rail traffic: theory of vehicle-track-soil interaction and measurements on high-speed lines. J Sound Vib 284(1):103–132Di Mino G, Di Liberto M (2007) Modelling and experimental survey on ground borne vibration induced by rail traffic. 4th international SIIV congress, 12–14 September, PalermoAlves P, Calçada R, Silva A (2012) Ballast mats for the reduction of railway traffic vibrations. Numerical study. Soil Dyn Earthq Eng 42:137–150Karlström A, Boström A (2007) Efficiency of trenches along railways for trains moving at sub- or supersonic speeds. Soil Dyn Earthq Eng 27:625–641Wolfe S, Humphrey D, Wetzel E (2004) Development of tire shred underlayment to reduce ground-borne vibration from LRT track. Geotechnical engineering for transportation projects. Proceedings of geotrans, vol 126. pp 750–759ASTM (2002) C215:2002. Standard test method for fundamental transverse, longitudinal, and torsional resonant frequencies of concrete specimensGuimond-Barrett A, Nauleau E, Le Kouby A, Pantet A, Reiffsteck P, Martineau F (2013) Free–free resonance testing of in situ deep mixed soils. Geotech Test J 36(2):1–9. doi: 10.1520/GTJ20120058Spanish Ministry of Public Works (2006) Pliego de Prescripciones Técnicas Generales de Materiales Ferroviarios PF-7: Subbalasto (general technical specifications for railway materials PF-7: subballast). Boletín Oficial del Estado 103:16891–16909ADIF (2008) Pliego de Prescripciones Técnicas Tipo para los Proyectos de Plataforma PGP-2008 (techical specifications for railway platform projects PGP-2008)Singh B, Vinot V (2011) Influence of waste tire chips on strength characteristics of soils. J Civ Eng Archit 5(9):819–827Martínez P, Villalba I, Botello F, Insa R (2013) Monitoring and analysis of vibration transmission for various track typologies. A case study. Transp Res Part D 24:98–109Wolfram Research Inc (2008) Mathematica [software], version 7.0, ChampaignISO (2003) Mechanical vibration and shock. Evaluation of human exposure to whole-body vibration. Part 2: vibration in buildings (1–80 Hz)Feng ZY, Sutter KG (2000) Dynamic properties of granulated rubber/sand mixtures. Geotech Test J 23(3):338–344AENOR (1994) UNE EN 29052-1:89. Acoustics—determination of the dynamic stiffness. Part 1: materials used under floating floors in dwelling

Characterisation of an unbound granular mixture with waste tyre rubber for subballast layers

Scrap tyres are a solid waste material produced in large quantities. One potential way of disposal is to use rubber particles from shredded tyres as a construction material. Within this context, this paper presents a comprehensive set of laboratory and field tests carried out to evaluate the characteristics of coarse aggregates mixed with rubber particles. The main objective is to assess whether these mixes could be used to form the subballast layer in new railway lines. All the technical features usually required for subballast were tested, including degradation, bearing capacity, density, resilient modulus, etc. The results show that adding between 1 and 10 % of rubber (in weight) improves resistance to degradation. On the other hand, bearing capacity is reduced, but still well over the usual range for common subballast if the rubber content is limited to <5 %. Moreover, the extension and compaction of these mixes can be done using conventional construction equipment.Martínez Fernández, P.; Medel Perallon, E.; Hidalgo Signes, C.; Insa Franco, R. (2015). Characterisation of an unbound granular mixture with waste tyre rubber for subballast layers. Materials and Structures. 48(12):3847-3861. doi:10.1617/s11527-014-0443-zS384738614812Sharma VK, Fortuna F, Mincarini M, Berillo M, Cornacchia G (2000) Disposal of waste tyres for energy recovery and safe environment. Appl Energy 65(1–4):381–394Commission European (1999) Directive on the Landfill of Waste 1999/31/EC. Off J Eur Union 182:1–19ASTM D6270-98 (1998) Standard practice for use of scrap tires in civil engineering applications. ASTM, West ConshohockenCommission European (2008) Waste Framework Directive 2008/98/EC. Off J Eur Union 312:3–30SIGNUS (2012) Activity Report 2012. Available at: http://www.signus.es/ . Accessed 2 July 2014Edinçliler A, Baykal G, Saygılı A (2010) Influence of different processing techniques on the mechanical properties of used tires in embankment construction. Waste Manag 30:1073–1080Sheehan PJ, Warmerdam JM, Ogle S, Humphrey DN, Patenaude SM (2006) Evaluating the risk to aquatic ecosystems posed by leachate from tire shred fill in roads using toxicity tests, toxicity identification evaluations and groundwater modeling. Environ Toxicol Chem 25(2):400–411Humphrey DN, Blumenthal M (2010) The use of tire-derived aggregate in road construction applications. Green Streets Highw 2010:299–313Humphrey DN, Whetten N, Weaver J, Recker K (2000) Tire shreds as lightweight fill for construction on weak marine clay. In: Proceedings of the international symposium on coastal geotechnical engineering in practice. Balkema, RotterdamWolfe SL, Humphrey DN, Wetzel EA (2004) Development of tire shred underlayment to reduce groundborne vibration from LRT track. Geotechnical engineering for transportation projects: Proceedings of Geo-Trans 2004, pp 750–759. ISSN:0-7844-0744-4Cano H, Estaire J, Rodríguez R (2011) Terraplén Experimental construido con Neumáticos Troceados (Experimental embankment built with shredded tyres). Jornada Técnica Sobre Experiencias Recientes en Estructuras de Tierra para Infraestructuras Viarias. Madrid, 10 Feb 2011Di Mino G, Di Liberto M, Maggiore C, Noto S (2012) A dynamic model of ballasted rail track with bituminous sub-ballast layer. Procedia 53:366–378Wang J, Zeng X (2004) Numerical simulation of vibration attenuation of high-speed train foundations with varied trackbed underlayment materials. J Vib Control 10:1123–1136Buonanno A, Mele R (2000) The use of bituminous mix sub-ballast in the Italian State Railways. 2nd Eurasphalt & Eurobitume Congress, Barcelona, 20–22 Sept 2000Feng Z, Sutter K (2000) Dynamic properties of granulated rubber/sand mixtures. Geotech Test J 23(3):338–344Nakhaei A, Marandi SM, Sani Kermani S, Bagheripour MH (2012) Dynamic properties of granular soils mixed with granulated rubber. Soil Dyn Earthq Eng 43:124–132Salgado R, Yoon S, Zia Siddiki N (2003) Construction of tire shreds test embankment. Joint Transportation Research Program. Technical Report Nº: FHWA/IN/JTRP-2002/35. Available at: http://docs.lib.purdue.edu/jtrp/42/ . Accessed 11 Feb 2013Yoon S, Prezzi M, Zia Siddiki N, Kim B (2005) Construction of a test embankment using a sand–tire shred mixture as fill material. Waste Manag 26:1033–1044Melis M (2006) Terraplenes y balasto en Alta Velocidad Ferroviaria (Embankment and ballast in high speed railways). Revista de Obras Públicas 3464:7–36Vipulanandan C, Bilgin Ö, Jeannot Y, Vembu K, Bahadir M (2009) Prediction of embankment settlement over soft soils. Project Report Nº FHWA/TX-09/0-5530-1. Available at: http://d2dtl5nnlpfr0r.cloudfront.net/tti.tamu.edu/documents/0-5530-1.pdf . Accessed 30 June 2014Spanish Ministry of Public Works (2006) Pliego de Prescripciones Técnicas Generales de Materiales Ferroviarios PF-7: Subbalasto (General Technical Specifications for Railway Materials PF-7: Subballast). Boletín Oficial del Estado 103:16891–16909ADIF (2008) ‘Pliego de Prescripciones Técnicas Tipo para los Proyectos de Plataforma PGP-2008 (Technical specifications for Railway Platform Projects PGP-2008)ASTM D75/D75M-09 (2009) Standard practice for sampling aggregates. ASTM, West ConshohockenSpeir RH, Witczak MW (1996) Use of shredded rubber in unbound granular flexible pavement layers. Transp Res Rec 1547:96–106Garnica PA, Pérez GN, Gomes LA (2001) Módulo de Resiliencia en Suelos Finos y Materiales Granulares. (Resilient Modulus in Fine Soils and Aggregate Materials). Publicación Técnica, 142, Secretaría de Comunicaciones y Transportes (SCI), Instituto Mexicano del Transporte (IMT), SanfandilaTutumluer E, Seyhan U (1999) Laboratory determination of anisotropic aggregate resilient moduli using a new innovative test device. 78th Annual meeting of the transportation research board specialty session on “Determination of resilient modulus for pavement design”, Washington, DCAASHTO T307-99-UL (2003) Standard method of test for determining the resilient modulus of soils and aggregate materials. AASHTO, Washington, DCFGSV: Earthworks and Foundation Engineering Task Force ZTVE-StB 94 (1994) Supplementary technical terms and conditions of contract and guidelines for earthworks in road constructionSETRA (2005) Informative Note 114. Éléments techniques pour la conception et la realization de planches d’essais de compactage dans les chantiers de terrassements (Technical elements for the conception and construction of compaction test boards on earthwork sites)Hataf N, Rahimi MM (2006) Experimental investigation of bearing capacity of sand reinforced with randomly distributed tire shreds. Constr Build Mater 20(10):910–916National Cooperative Highway Research Program (2004) Research results digest. Laboratory determination of resilient modulus for flexible pavement design. Available at: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_285.pdf . Accessed 1 Apr 2014Brown SF, Pappin JW (1985) Analysis of pavements with granular bases. Transp Res Rec 1022:52–59Araya AA, Huurman M, Molenaar AAA, Houben LJM (2012) Investigation of the resilient behavior of granular base materials with simple test apparatus. Mater Struct 45:695–705Mohammad LN, Puppala A, Alavalli P (1999) Effect of strain measurements on resilient modulus of granular soils. Dynamic geotechnical testing, vol 2, ASTM STP 1213, pp 202–221Gudishala R (2004) Development of resilient modulus prediction models for base and subgrade pavement layers from in situ devices test results. PhD thesis, Sri Krishnadevaraya University, AnantapurGerman Railways NGT 39 (1997) Richtlinie für die Anwendung des Leichten Fallgewichtsgerätes im Eisenbahnbau. (Directions of application of light drop-weight tester in railways)ASTM D3017 (2001) Standard test method for water content of soil and rock in place by nuclear methods (shallow depth). ASTM, West ConshohockenASTM D2922 (2001) Standard test methods for density of soil and soil-aggregate in place by nuclear methods (shallow depth). ASTM, West ConshohockenASTM D1883 (2005) Standard test method for CBR (California bearing ratio) of laboratory compacted soils. ASTM, West ConshohockenASTM C131 (2006) Standard test method for resistance to degradation of small-size coarse aggregate by abrasion and impact in the Los Angeles machine. ASTM, West ConshohockenASTM D5821 (2006) Standard test method for determining the percentage of fractured particles in coarse aggregate. ASTM, West ConshohockenASTM D4959 (2007) Standard test method for determination of water (moisture) content of soil by direct heating. ASTM, West ConshohockenASTM D6913 (2009) Standard test methods for particle-size distribution (gradation) of soils using sieve analysis. ASTM, West ConshohockenASTM D2419 (2009) Standard test method for sand equivalent value of soils and fine aggregate. ASTM, West ConshohockenASTM D4694 (2009) Standard test method for deflections with a falling-weight-type impulse load device. ASTM, West ConshohockenASTM D4318 (2010) Standard test methods for liquid limit, plastic limit, and plasticity index of soils. ASTM, West ConshohockenASTM D5084 (2010) Standard test methods for measurement of hydraulic conductivity of saturated porous materials using a flexible wall permeameter. Method B and C. ASTM, West ConshohockenASTM D6928 (2010) Standard test method for resistance of coarse aggregate to degradation by abrasion in the Micro-Deval apparatus. ASTM, West ConshohockenASTM D3080/D3080M (2011) Standard test method for direct shear test of soils under consolidated drained conditions. ASTM, West ConshohockenASTM D7181 (2011) Standard test method for consolidated drained triaxial compression test for soils. ASTM, West ConshohockenASTM C127 (2012) Standard test method for density, relative density (specific gravity), and absorption of coarse aggregate. ASTM, West ConshohockenASTM D7760 (2012) Standard test method for measurement of hydraulic conductivity of tire derived aggregates using a rigid wall permeameter. ASTM, West ConshohockenASTM D1557 (2012) Standard test methods for laboratory compaction characteristics of soil using modified effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)). ASTM, West ConshohockenASTM D2974 (2013) Standard test methods for moisture, ash, and organic matter of peat and other organic soils. ASTM, West ConshohockenBS 1377-5 (1990) Methods of test for soils for civil engineering purposes. Compressibility, permeability and durability tests. British Standards Institution, LondonBS 1377-9 (1990) Methods for test for soils for civil engineering purposes. In-situ tests: determination of the vertical deformation and strength characteristics of soil by the plate loading. British Standards Institution, LondonCEDEX NLT-148/91 (1991) Toma de muestras de roca, escorias, grava, arena, polvo mineral y bloques de piedra empleados como materiales de construcción de carreteras (Sampling of rocks, slags, sand, mineral dust and stone blocks used for road construction)CEDEX NLT-357:98 (1998) Ensayo de carga con placa (Load plate test)RENFE N.R.V. 2-1-0.0 ss(1982) Obras de Tierra, Calidad de la Plataforma. (Earthworks, platform quality

Environmental evaluation of a self-compacted clay based concrete with natural superplasticizers

[EN] Cement concrete is the most widely used construction material worldwide due to its favourable mechanical characteristics. However, it is responsible for 8% of the total carbon emissions in the world, which are generated mainly during the production of clinker. Due to that fact, finding alternatives to cement for some applications in which it is not strictly needed should be a priority. In this study, a self-compacted clay-based concrete with natural superplasticizers based on natural tara tannins is presented. The main objective of the study is to determine if this clay-based concrete can be a sustainable alternative to conventional cement concrete as the main component in structural slabs. The methodology of the study is divided into two parts. First, the self-compacting clay concrete is characterized to determine its mechanical properties. Secondly, a comparative Life Cycle Assessment is conducted to determine the difference between the impacts generated by one square meter of self-compacting cement concrete and one of self-compacting clay concrete. The characterization of the material showed that this self-compacting clay concrete is suitable for some building elements such as structural slabs while avoiding the energy consumption needed to produce conventional concrete. The environmental impact results showed that using self-compacting clay concrete instead of the cement-based material decreases 90% of the carbon emissions and 80% of the overall environmental impact. After the completion of the study, it can be stated that the presented material is a sustainable alternative to conventional concrete for building structural slabs.Romero Clausell, J.; Quintana-Gallardo, A.; Hidalgo Signes, C.; Serrano Lanzarote, AB. (2021). Environmental evaluation of a self-compacted clay based concrete with natural superplasticizers. Materials and Structures. 54(1):1-16. https://doi.org/10.1617/s11527-020-01586-611654

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

In this investigation, two different varieties of ‘Prada’ limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400 °C: (1) the explosion of certain samples and (2) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400, and 500 °C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO2 from 400 °C. This process jointly with the presence of microfissures in the dark texture, would cause a dramatic increase in pore pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400 °C. That result also points towards a significant contribution of oxidation of pyrites on the thermo-chemical damage of the rock, among other factors such as the pre-existence of microfissures and the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bears risk for mass fracturing and dramatic strength decay from 400 °C. Moreover, SO2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.This work was supported by the Spanish Government [Grant number RTI2018-099052-B-I00] and by the Department of Geological and Geotechnical Engineering, Universitat Politècnica de València

Thermal effects on the drilling performance of a limestone: relationships with physical and mechanical properties

This work evaluates the effect of high temperatures and cooling methods on the drillability of Prada limestone. Samples from boreholes drilled during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) were subjected to temperatures of 105, 200, 300, 400, and 600 °C, and then cooled at a slow rate or by quenching. Sievers’ J-value (SJ) and brittleness (S20) were determined on thermally treated samples, and the drilling rate index (DRI) was calculated for each temperature. The results show that thermal treatment implied a sustained increase in the drillability of the rock of up to 40% at 600 °C and a change in the drillability category (from medium to high). At 600 °C, SJ and S20 tripled and doubled, respectively, the initial values obtained for the intact rock. The results were inconclusive about the influence of the cooling method on the drilling performance of Prada limestone for the tested range of temperatures. The substantial improvement observed in the drillability of Prada limestone when heated, measured in terms of DRI, could help in the development of novel thermally-assisted mechanical excavation methods. Additionally, strong correlations between drillability variables (i.e., SJ and S20) and physical and mechanical variables of Prada limestone (i.e., P- and S-wave velocities, uniaxial compression strength, elastic modulus, and Poisson’s ratio) are proposed. Correlations will help make preliminary predictions of drillability based on properties such as uniaxial compression strength and ultrasound wave velocities.The authors wish to acknowledge David Benavente and Juan Carlos Canaveras from the University of Alicante, for their valuable help on mineralogical and petrographic description of the rock. Additionally, Kreum SA, Ayesa SA, Infraestructures de la Generalitat de Catalunya, S.A.U., and the Lleida regional roads authority (Servei Territorial de Carreteres de Lleida, Generalitat de Catalunya) for providing rock samples. This work was supported by the Department of Geological and Geotechnical Engineering, Universitat Politecnica de Valencia

Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres

[EN] During construction of road and railway projects, expansive soils may be encountered. Their use as construction material for embankments presents difficulties, due to their tendency to swell or shrink. Traditional solutions include mixing soil with cement or quicklime, or to import materials from other locations. As an alternative to these solutions, the present paper proposes a less expensive and more sustainable solution, consisting in mixing the natural expansive soil with rubber particles obtained from scrap tyres. Especially, the Facies Tap (a typical soil of southeastern Spain) is studied in this paper. This soil, which is mainly a white argillaceous marlstone, is mixed with six different amounts of rubber content (2.5, 5, 10, 15, 20 and 25% in terms of weight) and submitted to several geotechnical tests, including compaction, free swelling, unidimensional consolidation, direct shear testing and undrained shear compression. The addition of rubber particles to the soil up to a 15% makes it lighter and less prone to swelling, while compressibility remains similar to the natural soil and the drained shear strength slightly increases. Based on experimental results, the optimum rubber content mixed with the soil to prevent its swelling is established at around 3%.Hidalgo Signes, C.; Garzón-Roca, J.; Martínez Fernández, P.; Garrido De La Torre, ME.; Insa Franco, R. (2016). Swelling potential reduction of Spanish argillaceous marlstone Facies Tap soil through the addition of crumb rubber particles from scrap tyres. Applied Clay Science. 132-133:768-773. doi:10.1016/j.clay.2016.07.027S768773132-13

A New SJ* Value Based on Sievers' J-Miniature Drill Tests to Determine the Drillability of Limestones

[EN] This research presents a new drillability value (SJ*) that corrects the most-used Sievers¿ J-value (SJ) by removing the accommodation effect of the drill bit in the first tenths of a millimetre to better represent the real drillability of limestones. Moreover, this research demonstrates how such an effect is more notable when porosity and micro-cracking increase, which in this study has been achieved by inducing thermal damage in the samples. To do so, limestone samples from the Prada formation were subjected to temperatures of 105, 300 and 600 °C and then cooled at fast and slow rates to induce porosity and micro-cracking. Two characteristic zones were identified in the penetration¿time plots: (a) a shallow region (Zone 1) with a variable drilling rate including an initial peak and (b) a deeper region (Zone 2) where the drilling rate stabilises. These drilling rates increase with thermally induced porosity and mi-cro-cracking, and the authors propose a new method to delimit Zones 1 and 2. Zone 1 is attributed to the time it takes for the drill bit to adjust and settle in the rock surface, while Zone 2 more realistically represents the drillability of the material. The above influ-ences the SJ value derived from Sievers¿ J-miniature drill tests, so a new drillability value SJ* is proposed that corrects SJ by ex-cluding Zone 1 and giving more weight to Zone 2. The novel SJ* presented in this research constitutes a more accurate tool to assess and predict the drilling performance in limestones.This research received no external funding. The author, Roberto Tomas, is supported by the Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital within the framework of the CIAICO/2021/335 project.Martínez Ibáñez, V.; Garrido De La Torre, ME.; Hidalgo Signes, C.; Tomás, R.; Álvarez-Fernández, M. (2023). A New SJ* Value Based on Sievers' J-Miniature Drill Tests to Determine the Drillability of Limestones. Sustainability. 16(1):1-17. https://doi.org/10.3390/su1601000811716

Predicting the Uniaxial Compressive Strength of a Limestone Exposed to High Temperatures by Point Load and Leeb Rebound Hardness Testing

The effect of exposure to high temperature on rock strength is a topic of interest in many engineering fields. In general, rock strength is known to decrease as temperature increases. The most common test used to evaluate the rock strength is the uniaxial compressive strength test (UCS). It can only be carried out in laboratory and presents some limitations in terms of the number, type and preparation of the samples. Such constrains are more evident in case of rocks from historical monuments affected by a fire, where the availability of samples is limited. There are alternatives for an indirect determination of UCS, such as the point load test (PLT), or non-destructive tests such as the Schmidt’s hammer, that can also be performed in situ. The aims of this research are: (i) measuring the effect of high temperatures and cooling methods on the strength and hardness of a limestone named Pedra de Borriol widely used in several historic buildings on the E of Spain, and (ii) studying the possibility of indirectly obtaining UCS by means of PLT and Leeb hardness tests (LHT), using Equotip type D. Limestone samples were heated to 105 (standard conditions), 200, 300, 400, 500, 600, 700, 800 and 900 ºC and cooled slowly (in air) and quickly (immersed in water). After that, UCS, PLT and LHT tests were performed to evaluate the changes as temperature increases. Results show decreases over 90% in UCS, of between 50 and 70% in PLT index and smaller than 60% in LHT index. Insignificant differences between cooling methods were observed, although slowly cooled samples provide slightly higher values than quickly cooled ones. The results indicate that LHT can be used to indirectly estimate UCS, providing an acceptable prediction. Research on correlating strength parameters in rocks after thermally treated is still scarce. This research novelty provides correlations to predict UCS in historic buildings if affected by a fire, from PLT and non-destructive methods such as LHT whose determination is quicker and easier.The authors acknowledge the support by Canteras Bernad SL which has generously provided samples, and Department of Geotechnical and Geological Engineering of Universitat Politècnica de València and Department of Civil Engineering of Universidad de Alicante, for its continuous support. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature