Empleo de cenizas de fondo de central térmica y cal como filler en mezclas bituminosas

This study focuses on the characterization of bottom ash (PCC-BA) and determining the mechanical characteristics of hot mix asphalt (HMA) using PCC-BA and hydrated lime (HL) as filler. Physical and chemical characterization of the bottom ash was carried out to evaluate its eventual reutilization as filler substitute. The materials tested in this study were made using 0%, 25%, 50%, 70% and 100% of PCC-BA combined with HL. HMA mixes were evaluated in terms of their engineering properties, namely: air voids in the mixes, water sensitivity, stiffness modulus, performance in wheel tracking test and fatigue resistance. The results obtained indicate that HMA mixes with a filler blend of 70% PCC-BA and 30% HL fulfil European standards and are suitable for light traffic or small infrastructures.Este estudio se centra en la caracterización de las cenizas de fondo (PCC-BA) y la determinación de las características mecánicas de mezclas bituminosas en caliente (HMA), utilizando cenizas de fondo y la cal hidratada (HL) como filler. Se realizó la caracterización física y química de las cenizas de fondo para evaluar su empleo como sustituto de filler. Las mezclas ensayadas en este estudio se realizaron utilizando 0%, 25%, 50%, 70% y 100% de cenizas de fondo combinadas con cal hidratada. Se evaluaron propiedades ingenieriles de las mezclas bituminosas, tales como los huecos de aire en las mezclas, la sensibilidad al agua, el módulo de rigidez, el ensayo de pista y la resistencia a la fatiga. Los resultados obtenidos indican que las mezclas bituminosas fabricadas con una combinación de filler del 70% de cenizas de fondo y el 30% cal hidratada, cumplen con las normas europeas y son adecuados para su aplicación con tráficos ligeros o en pequeñas infraestructuras

Comparative analysis of the performance of asphalt concretes modified by dry way with polymeric waste

An asphalt concrete has been modified by adding four polymeric wastes: polyethylene (PE) from micronized containers, polypropylene (PP) from ground caps, polystyrene (PS) from hangers and rubber from end-of-life tyres (ELT). These polymeric wastes were selected according to their availability, homogeneity and economic criteria considering the big amount of material required to build a road. The dry method has been used to modify the bituminous mixture due to its simplicity and the possibility to be carried out in any asphalt plant without important modifications. This is very important in order to spread the process and recycle the polymeric waste in the same place where it is produced, hence improving the environmental impact. The reference asphalt mixture and the four modified asphalt concretes have been analysed separately and their performance compared, evaluating their resistance against plastic deformation, stiffness, fatigue resistance and workability. The Master curve and the Black diagram of the mixtures were also calculated. The results showed that the use of polymeric wastes significantly increased the stiffness of the reference mixture in all cases, but especially when PE, PP and ELT were used. However, none of these materials significantly modifies the fatigue behaviour of the reference mixture. Regarding the resistance against plastic deformation, the use of both PE and ELT led to an increase of the resistance, whereas PP did not modify it and PS decreased it. As for workability, the energy of compaction of the modified mixtures did not suffer any important change. Therefore, according to the results obtained, PE, PP and ELT can be used to modify asphalt mixtures since they improve or do not change their properties. On the other hand, PS should be further studied because of the contradictory results obtained, and only when plastic deformation is not a problem this material could be used.POLYMIX is a project financed by the “LIFE+” program of the European Union, with reference number LIFE10 ENV ES 516. This project was carried out by a consortium coordinated by GITECO (Construction Technology Applied Research Group, University of Cantabria) and integrated by ACCIONA Infrastructures, AIMPLAS (Research Association of Plastic Materials), and VIA-M (Department of Road Construction from the Madrid Regional Government). The authors wish to acknowledge and especially thank Belén Monje and Eva Verdejo (AIMPLAS) and Raquel Casado and Elena Sáez (ACCIONA) for their collaboration

Damage evaluation during installation of geosynthetics used in asphalt pavements

Geosynthetics are commonly used as anti-reflective cracking systems in asphalt pavements. The rehabilitation design methods use the characteristics of as-received geosynthetics as inputs. However, these materials undergo physical damage during their installation due to mechanical and thermal loads which currently are not taken into account in the design processes. These loads can produce a reduction in geosynthetic strength and therefore, it is necessary to know the secant modulus after installation in order to improve the pavement design incorporating these materials. The secant modulus of a material indicates its initial stiffness. This paper describes an experimental study of damage due to installation of five different geosynthetics using three different procedures: (i) mechanical damage induced in the laboratory considering the action of aggregates, (ii) in situ mechanical and thermal damage due to actual installation in a test section, and (iii) a new mechanical and thermal damage experimental test developed with the aim of reproducing the real installation conditions. The main results of the study indicate that the obtained secant modulus of the tested geosynthetics reduced after applying the three damage procedures, and the loss of properties differed depending on the type and constitutive material and on the applied damage procedure.This investigation was supported by the research Project ‘Rehabilitation of roads and highways (REHABCAR)’ file number IPT-370000–2010–029, led by DRAGADOS (ACS Group), in collaboration with GEOCISA and ASFALTOS AUGUSTA among others. The project has been funded by the Ministry of Economy and Competitiveness (MINECO) within the National Plan for Scientific Research, Development and Innovation 2008–2011 (INNPACTO 2010) and the European Union under ERDF Funds (European Regional Development Fund)

Density, adhesion and stiffness of warm mix asphalts

XI Congreso de Ingeniería del Transporte (CIT 2014)This study presents the results of different laboratory tests related to the density, adhesion (sensitivity to water test) and rigidity (resilient module) of bituminous mixtures, manufactured at three different temperatures (160 °C, 140 °C and 120 °C), with three additives: a surfactant made up of different amino substances, a paraffin obtained by the Fisher-Tropsch synthesis process which is totally soluble in bitumen, and a synthetic zeolite in powder form which causes the bitumen to micro-foam,. Test samples have been compacted by impact, according to the Marshall method, and kneading, according to gyratory machine. To evaluate these properties an asphalt concrete mixture has been chosen, with a binder, B-50/70, and a maximum size of aggregates of 16 mm, which is usually placed in the surface layer of the pavement. The densities obtained by the two compaction methods are easy to reach. Densities will decrease if the temperature of manufacturing is lower. All mixtures compacted by gyratory machine at different temperatures displayed very good behavior of water sensitivity; but not all mixtures compacted by impact achieved this. The additives improve the adhesion between aggregate and binder. The stiffness moduli decreased in all mixtures for both types of compaction when the temperature was higher, and this reduction is less pronounced in the mixes manufactured with the gyratory compactor. Mixtures with additives tend to reduce the module, except paraffin.This paper is based on the results for the Fenix Project. The development of the Fenix Project was possible thanks to the financial contribution of the Center for Technological and Industrial Development (CDTI) within the framework of the Ingenio 2010 programme, through the CENIT Programme

Test methods and influential factors for analysis of bonding between bituminous pavement layers

The durability and maintenance of pavements depend on several factors. One of the most influential is the bond between layers. This bond is responsible for ensuring all layers behave as a single entity, reducing cracks and deformation of the pavement. Several methods, developed by different authors over the past 30 years, to measure bonding between layers are analyzed in this paper. Different research lines are discussed, concluding that the most influential variables are: tack coat type, dosage, mixture type, surface characteristics, temperature, and emulsion breaking time. In order to reach the highest bond strength values, the following factors should be considered: high values of surface macro-texture, low temperatures, the use of heat-adhesive emulsion, a dosage from 300 to 450 g/m2 of residual bitumen and the compaction after emulsion break. Moreover, a non-destructive test method to assess tack coat dosage on site is proposed

Mechanical behavior of asphalt mixtures containing silica gels as warm additives

This paper presents the results of a study of some compounds capable of absorbing water into their structure (silica gel), as potential foaming binders. Asphalt mixtures were manufactured at different manufacturing and compaction temperatures, using four different silica gels. Static and dynamic tests were carried out to determine their behavior in asphalt mixtures. The results were compared with those obtained using hot-mix asphalt and warm-mix asphalt manufactured with zeolite. The lab results showed a similar behavior of asphalt mixtures containing either silica gel or zeolite.The research presented herein was sponsored by the Research Office of Universidad de La Frontera (DIUFRO) under the project number DI15-0089

A straightforward method for determining SiGe HBTs intrinsic elements of hibrid PI and TEE small-signal circuit models for multibias operation

A new method to simultaneously determine the complete Tee and hybrid Pi equivalent circuit parameters of the SiGe HBT including parasitic intrinsic base resistance, is presented. This approach employs analytically derived expressions and is based on the analysis of measured scattering parameters over an adequate frequency range. This paper shows that a one-to-one correspondence exists between Tee and Pi topologies and very good fit between measured and simulated scattering parameters in the frequency range between 0.05 to 50 GHz is obtained

Optical Control of a GaAs Chip MMIC Amplifier at S Band

This paper shows the results of research on the optical control of a GaAs chip monolithic amplifier,and is an extension of previous work by our group in the field of optical-microwave interaction [1-3 ].The amplifier was originally designed for the transmitter stage of an indoor mobile communications system in the 2.4 GHz band.The possibilities of optical control of this amplifier are evidenced as follows:if the amplifier operates with the same biasing, the gain can be optically controlled from a condition of almost isolation,(small signal gain less than -5 dB),up to an active condition,(small signal gain greater than 10 dB), which gives a range of optical control of about 15 dB.At the same time,the optical control provides an improvement of the input and output matching in a range of 12dB and 6dB, respectively.This optical control suggests an interesting control of gain and matching for other microwave FET based active devices

New Large Signal Model of AlGaAs P-HEMT and GaAs MESFET Under Optical Illumination

As an extension of previous works in the optical-microwave interaction field, this paper shows the results of the research on large signal dynamic behaviour (Pulsed I/V curves) of AlGaAs P-HEMT (pseudomorphic high electron mobility transistor) devices, in the overall I/V plane, when the incident optical input power is changed. A complete bias and optical power dependence of the large signal model for a P-HEMT, is determined from experimental scattering parameters, DC and pulsed measurements. All derivatives of the model shown here are continuous for a realistic description of circuit distortion and intermodulation. The model is also valid for GaAs MESFET. experimental results show very good agreement with theoretical analysis