Papers by Fernando MARTINEZ SOTO
Journal of Cultural HeritageVolume 52, Pages 31 - 37, 2021
Spectral Analysis of Surface Waves (SASW) is an in-situ non-destructive testing technique which a... more Spectral Analysis of Surface Waves (SASW) is an in-situ non-destructive testing technique which allows to evaluate historic masonry buildings by characterising the mechanical properties of the materials without damaging the structure. This paper presents the theoretical bases of this technique and describes its application on an existing masonry structure, the church of San Justo y Pastor in Granada (Spain). The elastic modulus, shear modulus and Poisson's ratio of the two carbonate rocks composing the building were calculated, obtaining results that are in agreement with previous studies using different testing techniques. The results of the study indicate the usefulness of SASW method to evaluate heritage buildings, taking into account the existing variability of the mechanical properties throughout the structure.
Journal of Building Engineering, 2023
Free-Free Resonant Column and Spectral Analysis of Surface Waves are two nondestructive testing t... more Free-Free Resonant Column and Spectral Analysis of Surface Waves are two nondestructive testing techniques which are becoming increasingly relevant in construction engineering, as they offer the possibility of assessing the mechanical properties of the building materials without damaging the sample. In the present study, these two testing methods are applied on concrete samples with increasing curing times, from 9 h to 60 days, estimating the dynamic elastic modulus and proposing relationships to obtain the compressive strength from these values. The nondestructive results are compared with the actual strength of the material obtained via uniaxial compression tests, proving the accuracy of the proposed nondestructive testing methodologies, even for early ages. SASW tests are also carried out on a reinforced concrete sample, concluding that the presence of the reinforcement does not alter the results of the test.
Spectral analysis of surface waves for non-destructive evaluation of historic masonry buildings Journal of Cultural Heritage Volume 52, November–December 2021, Pages 31-37, 2021
Spectral Analysis of Surface Waves (SASW) is an in-situ non-destructive testing technique which a... more Spectral Analysis of Surface Waves (SASW) is an in-situ non-destructive testing technique which allows to evaluate historic masonry buildings by characterising the mechanical properties of the materials without damaging the structure. This paper presents the theoretical bases of this technique and describes its application on an existing masonry structure, the church of San Justo y Pastor in Granada (Spain). The elastic modulus, shear modulus and Poisson's ratio of the two carbonate rocks composing the building were calculated, obtaining results that are in agreement with previous studies using different testing techniques. The results of the study indicate the usefulness of SASW method to evaluate heritage buildings, taking into account the existing variability of the mechanical properties throughout the structure.
Using Spectral Analysis of Surface Waves to characterize construction materials in built Cultural Heritage: The Church of Saint Justo & Pastor, 2018
This paper introduces a methodology to measure material properties in heritage masonry structures... more This paper introduces a methodology to measure material properties in heritage masonry structures using Non-destructive Methods (NDT). This study aims to analyze the feasibility and effectiveness of Spectral Analysis of Surface Waves Method (SASW) to determinate the material properties of historical buildings. These material properties are subject to change on account of applied loads and environmental conditions.
SASW technique involves measurement of the time needed for an induced pulse to pass along the surface of the material.
The SASW method involves signal processing techniques similar to those used in the impact-echo (IE), impulse-response and free-free resonant column methods (FFRC), but information about the structure of the material, depth, change of thickness or different material used in the construction of the historical heritage is extracted through the profile of velocities generated by the series of superficial impacts made.
The speed of propagation is calculated according to the contact time of the impact, the broader the range of the frequencies or wavelengths, and the distance between the transducers. The Rayleigh wave velocity is related to Poisson’s ratio, material density, and dynamic material stiffness. The advantage of this technique is that only measurements in the surface area are needed, therefore simplifying the experimental setup.
The obtained results allow representing the wave dispersion curves of Rayleigh Wave, which can be used to infer the elastic properties of the underlying material.
In this study, we describe SASW surveys in the tambour and the dome of the Church of the San Justo y Pastor in Granada. The results obtained are in agreement with results found in the literature.
Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-tra... more Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-track section. The recycled rubber has become an enhancer of the modified bituminous mixtures. In this work, it has been shown as a sustainable improvement option in HMA mixes due to the elastic behavior exposed by the rubber particles. The impact of thermal susceptibility on the mechanical properties of the railway bituminous sub-ballast layer has served to the advanced measurement of the thermal cycles inside the rail track. Different simulations following the Kentrack and Kenpave software were employed to be effective with the best mix-design for railways. According to weather situation, reviewed temperature models were used to prove the effectiveness of the railway superstructure. It is included the assessment of improved modified asphalt mixes with coarse rubber from scrap tires, containing 1.5-3% of rubber (sizes 0.2-4mm) by weight of the total mix. Adopting the Volumetric mix-design by the dry process was enhanced the characterization of rubberized materials after computer simulations to evaluate stresses derived from the rail traffic and the average seasonal temperatures. The stiffer-elastic sustainable rubberized mixes showed that is useful in the reduction of rail track damping vibrations.
The objectives of this study are focused on the ideal methodology and the dimensioning of the rai... more The objectives of this study are focused on the ideal methodology and the dimensioning of the railway superstructure , involving the use of a bituminous sub-ballast layer modified with recycled natural rubber tire out-of-use. The previous study of the thermal transmission in each Railtrack layer, the analysis of the traffic in high-speed lines and the revision of the thermal-mechanical models have motivated this research. An experimental methodology has been optimized for the application of the volumetric mix-design with the gyratory compactor (SGC). According to the meteorological situation and applying experimental models based on thermal conductivity interpolated by sinusoidal functions, a laboratory study of conventional bituminous mixtures and improved mixtures of asphalt modified with coarse rubber waste tires is illustrated. The enhanced methodology entails a case study where compacted mixes are used by SGC, replacing rubber between 1.5 and 3 percent of rubber (particle size 0.2-4 mm) in the total weight of the blend. After the evaluation of the average seasonal temperatures, the mixtures were designed considering the dry process, as an advanced measure of sustainability and for their demonstrated improvements in thermal behavior and resistance to fatigue. A step-by-step manufacturing process is provided to avoid swelling problems in the post-compaction phase characteristic of dry mixes. The purpose of using rubber modifiers in the hot mix asphalt has been achieved to obtain an elastic sustainable material for the evaluation of its behavior in sub-ballast layers.
CITE AN ARTICLE
Soto, F. M., & Di Mino, G. (2018). “Improvements in the mix-design, performance features and rational methodology of rubber modified binders for the thermal evaluation of the railway sub-ballast”, (IJRSM/F09/17) International Journal of Research Science and Management, ISSN: 2349-5197, Volume 5, Issue 2, February 2018].
The design of an unmodified bituminous mixture and three rubber-aggregate mixtures containing rub... more The design of an unmodified bituminous mixture and three rubber-aggregate mixtures containing rubber-aggregate by a dry process (RUMAC) was evaluated, using an empirical-analytical approach based on experimental findings obtained in the laboratory with the volumetric mix design by gyratory compaction. A reference dense-graded bituminous sub-ballast mixture (3% of air voids and a bitumen 4% over the total weight of the mix), and three rubberized mixtures by dry process (1,5 to 3% of rubber by total weight and 5-7% of binder) were used applying the Superpave mix-design for a level 3 (high-traffic) design rail lines. The railway tracked section analyzed was a granular layer of 19cm compacted, while for the sub-ballast a thickness of 12cm has been used. To evaluate the effect of increasing the specimen density (as a percent of its theoretical maximum specific gravity), in this article, are illustrated the results obtained after different comparative analysis into the influence of varying the binder-rubber percentages under the sub-ballast layer mix-design. This work demonstrates that rubberized blends containing crumb and ground rubber in bituminous asphalt mixtures behave at least similar or better than conventional asphalt materials. By using the same methodology of volumetric compaction, the densification curves resulting from each mixture have been studied. The purpose is to obtain an optimum empirical parameter multiplier of the number of gyrations necessary to reach the same compaction energy as in conventional mixtures. It has provided some experimental parameters adopting an empirical-analytical method, evaluating the results obtained from the gyratory-compaction of bituminous mixtures with an HMA and rubber-aggregate blends. An extensive integrated research has been carried out to assess the suitability of rubber-modified hot mix asphalt mixtures as a sub-ballast layer in railway underlayment tracked. Design optimization of the mixture was conducted for each mixture and the volumetric properties analyzed. Also, an improved and complete manufacturing process, compaction and curing of these blends are provided. By adopting this increase-parameters of compaction, called " beta " factor, mixtures modified with rubber with uniform densification and workability are obtained that in the conventional mixtures. It is found that considering the usual bearing capacity requirements in rail track, the optimal rubber content is 2% (by weight).
INTERNATIONAL JOURNAL OF ENGINEERING
SCIENCES & RESEARCH TECHNOLOGY, 7(1), 483-507.
DOI: 10.5281/zenodo.1158653
The design of a reference dense-graded bituminous sub-ballast mixture (3% of air voids and a bitu... more The design of a reference dense-graded bituminous sub-ballast mixture (3% of air voids and a bitumen 4% over the total weight of the mix) and three rubber-aggregate mixtures containing ground rubber-aggregate by a dry process (RUMAC to 1,5 to 3% of rubber by total weight and 5-7% of binder) was evaluated. Using an eco-sustainable original approach based on experimental findings obtained in the laboratory with the Volumetric mix-design by gyratory compaction for a level 3 (high-traffic) design rail lines. This work proves that rubberized blends having ground rubber in bituminous asphalt mixtures behave better than conventional asphalt materials. By using the same method of volumetric compaction, the densification curves resulting from each mixture have been studied with the purpose to obtain a best empirical parameter multiplier of the number of gyrations necessary to reach the same compaction energy as in conventional mixes. It has provided experimental parameters evaluating the results obtained from the gyratory-compaction of bituminous mixtures with an HMA and rubber-aggregate blends as a sub-ballast layer in railway underlayment trackbed. By adopting this increase-parameters of compaction, called " beta " factor, uniform densification and higher workability are found in modified mixtures with rubber considering the usual bearing capacity requirements in rail track.
CItation: Martínez Soto, F. (2018) “Eco-Sustainable optimization of the mix-design methodology in modified bituminous mixtures with high percentage of recycled tire rubber,” (GJESRM/A008/18) Global Journal of Engineering Science and Research Management, ISSN: 2349-4506, DOI: 10.5281/zenodo.1156460 [Volume 5, Issue 1, Nº5, pp. 37-58, January 2018].
Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-tra... more Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-track section. The recycled rubber has become an enhancer of the modified bituminous mixtures. In this work, it has been shown as a sustainable improvement option in HMA mixes due to the elastic behavior exposed by the rubber particles. The impact of thermal susceptibility on the mechanical properties of the railway bituminous sub-ballast layer has served to the advanced measurement of the thermal cycles inside the rail track. Different simulations following the Kentrack and Kenpave software were employed to be effective with the best mix-design for railways. According to weather situation, reviewed temperature models were used to prove the effectiveness of the railway superstructure. It is included the assessment of improved modified asphalt mixes with coarse rubber from scrap tires, containing 1.5-3% of rubber (sizes 0.2-4mm) by weight of the total mix. Adopting the Volumetric mix-design by the dry process was enhanced the characterization of rubberized materials after computer simulations to evaluate stresses derived from the rail traffic and the average seasonal temperatures. The stiffer-elastic sustainable rubberized mixes showed that is useful in the reduction of rail track damping vibrations.
DOI: 10.5281/zenodo.1173468
The study is focused on the ideal methodology and the dimensioning of the railway superstructure ... more The study is focused on the ideal methodology and the dimensioning of the railway superstructure , involving the use of a bituminous sub-ballast layer modified with recycled natural rubber tire out-of-use. The design of an unmodified bituminous mixture and three rubber-aggregate mixtures containing rubber-aggregate by a dry process (RUMAC) was evaluated, using an empirical approach based on experimental findings obtained in the laboratory with the volumetric mix-design by gyratory compaction. A reference dense-graded HMA mixture (3% of air voids and a 4% bitumen content over the total weight of the mixture) and different rubberized mixtures by a dry process (1,5 to 3% of rubber by total weight and 5-7% of binder) were evaluated. The Superpave mix-design for a level 3 (high-traffic) design rail lines was considered. The railway trackbed section analyzed was a granular layer of 19cm compacted, while for the sub-ballast a thickness of 12cm has been used to evaluate the effect of increasing the specimen density (as a percent of its theoretical maximum specific gravity). In this article, are illustrated the results obtained after different comparative analysis into the influence of varying the binder-rubber percentages under the sub-ballast layer mix-design. This work demonstrates that rubberized blends containing crumb and ground rubber in bituminous asphalt mixtures behave at least similar or better than conventional asphalt materials using the same methodology of volumetric compaction. The densification curves resulting from each mixture have been correlated to obtain an optimum empirical parameter multiplier of the number of gyrations necessary to reach the same compaction energy as in conventional mixtures. It has provided some experimental parameters adopting an empirical method, evaluating the results obtained from the gyratory-compaction of bituminous mixtures with an HMA and rubber-aggregate blends. Comprehensive, integrated research has been carried out to assess the suitability of rubber-modified hot mix asphalt mixtures as a sub-ballast layer in railway underlayment trackbed. Design optimization of the mixture was conducted for each mixture and the volumetric properties analyzed. Also, an improved and complete manufacturing process, compaction and curing of these blends are provided. By adopting new increase-parameters of compaction, called " beta " factors, mixtures modified with rubber with uniform densification and workability are obtained that in the conventional mixtures. It was found that the optimal rubber content is 2% (by weight) or 3.95% (by volumetric substitution) and a binder content of 6%.
The impact of temperature on the mechanical properties and thermal susceptibility of the railway ... more The impact of temperature on the mechanical properties and thermal susceptibility of the railway bituminous sub-ballast layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather situation, Barber's temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle size 0.2-4 mm) by weight of the total mix, as sub-ballast layer in railway and base layers on roads, recurring to the Superpave mix design compaction enhanced after computer simulations to evaluate real stresses derived from the rail traffic and climatic conditions. This article following the assessment of the average seasonal temperatures, involves the characterization of rubberized materials with attention to crumb rubber properties, designed with dry technology, to enhance the bitumen-rubber and binder-voids ratios. Indirect tensile strength and water sensitivity tests were applied for the evaluation of its mechanical properties including dynamic complex modulus at elevated temperature to measure the amount of bitumen absorbed by the rubber. The rubberized mix-results obtained and the comparison with a conventional HMA (hot mix asphalt) show that these dry rubber bituminous mixtures are particularly effective in damping vibrations. The purpose of using rubber modifiers in hot mix asphalt to obtain a stiffer-elastic sustainable material has been achieved for the assessment of its behavior in sub-ballast/base layers. Highlights An innovative approach for the volumetric design of bituminous mixture with rubber (dry process); Optimal parameters of temperature and traffic to characterize the mixture for a sub-ballast layer; Applicability of Barber forecasting model used in the field road, to the railway superstructure; Performance of the design process for the volumetric analysis of rubberized asphalt; 160 kN and 80 kN, respectively, rail equivalent axle load (R ESAL) were selected comparing sub-ballast vs. road base course solicitations induced for each layer; Increase of workability and compaction properties decreasing air voids content to 3%-4% of the total mix weight; Crumb rubber percentage between 1.5% to 2% and a digestion time of 120 min produced the optimal results.
Bituminous sub-ballast is an alternative solution to the unbound granular sub-ballast used in the... more Bituminous sub-ballast is an alternative solution to the unbound granular sub-ballast used in the railway track due to several
benefits that it can provide. Indeed, it contributes to maintain the moisture content in the subgrade unchanged during all year. This
decreases the subgrade deterioration process. Moreover, the presence of bituminous sub-ballast can also reduce vertical stiffness
variations on the track; it can have a positive effect in the maintenance needs at transition sections (bridge-embankment) and in the
attenuation of the vibrations induced by the rail traffic. Despite the importance of the presence of the bituminous sub-ballast to conceive
the construction and/or rehabilitation of sustainable infrastructure, in literature, there are only fragmentary information regarding the
definition of benchmark criteria for their mix design. The superpave mix design approach used in road domain is applied systematically
in the railway domain, without being adjusted for different load configuration of the rail track system. This research work aims at
defining the benchmark criteria for the bituminous sub-ballast mix design to reduce the approximations involved in the recipe
optimization due to the limitation of applying the superpave system in the railway domain. The methodology proposed aims at selecting
the RESAL (rail equivalent single axle load) and therefore, transforming the entire traffic spectrum on the track lines in number of
ESALs. Afterwards, the Ndesign has been calculated as function of the rail traffic level. Finally, a case study of bituminous sub-ballast
mix design has been investigated for a first verification of the methodology proposed.
8 Bituminous sub-ballast is an alternative solution to the unbound granular sub-ballast used in 9... more 8 Bituminous sub-ballast is an alternative solution to the unbound granular sub-ballast used in 9 the railway track. Indeed, it contributes to reduce the variation of the moisture content in the 10 subgrade, slowing its deterioration process. Moreover, the bituminous sub-ballast can also 11 reduce track vertical stiffness variations, maintenance needs at the transition sections and the 12 attenuation of the vibrations induced by the rail traffic. The SUPERPAVE mix design 13 approach is applied systematically to the railway domain, without been adjusted for the 14 different load configuration of the rail track system. This research aims at defining the 15 parameters for adapting the gyratory compaction methodology to the bituminous sub-ballast 16 mix-design optimization. The rail equivalent single axle load (RESAL) has been defined and 17 the traffic spectra of the track lines have been transformed to calculate the Ndesign as function 18 of the rail traffic levels. Finally, a case study of bituminous sub-ballast mix design has been 19 applied. 20 21
A wide integrated research has been carried out to assess the suitability of bituminous mixtures ... more A wide integrated research has been carried out to assess the suitability of bituminous mixtures as the sub-ballast layer in railways. The influence of temperature on the mechanical characteristics and thermal suscepti-bility of the bituminous conglomerate - which forms sub-ballast layer of railway lines - has provided the motivation for carrying out a measurement of the thermal cycles in this layer. The evaluation of the average seasonal temperatures has proven to be well interpolated by sinusoidal functions, of which characteristic pa-rameters are determined. To expand the validity of the study in different weather situations apart from Sicily, where the experiment was held, we proceeded to apply the Barber’s temperature model, used to validate pavement structures, which proved to be effective for the railway superstructure. A reference bituminous mix-ture according to the Italian standard was used applying the Superpave mix design. This article illustrates the re-sults obtained after different simulations, following the evaluation of the average seasonal temperatures.
The present paper aims at proposing a mix design approach specifically tailored for rubberized as... more The present paper aims at proposing a mix design approach specifically tailored for rubberized asphalt (dry process) that takes into account the behaviour of the crumb rubber during the compaction and post-compaction processes. An analytical approach to quantify the recovered deformation of the crumb rubber in the post-compaction phase has been developed in order to adjust the number of gyrations proposed by SUPERPAVE method when crumb rubber is used. The final goal is to define an appropriate compaction that allows meeting the requirements of voids content for the asphalt mixture considered. The energy stored by the rubber during the process has been calculated. Moreover, a mathematical relationship has been defined for computing the maximum allowable amount of rubber that it is possible to add to the mixture once the target voids content has been established. Finally, based on the results obtained, a full-steps protocol has been proposed in order to fabricate and compact CR mixtures in the laboratory.
The study of bituminous mixes can be related to tyre rubber material recycling. Encouraging scrap... more The study of bituminous mixes can be related to tyre rubber material recycling. Encouraging scrap tyre disposal and cutting down on pit employment are the environmental aims. In the field of railways, technological processes involved in the use of crumb rubber are the wet-dry processes. In the mechanical characterisation of the asphalt concrete in terms of both the fatigue resistance and the stiffness modulus it is necessary to use a design method for the sub-ballast railway material, even more so if the asphalt concrete investigated is an innovative material such as a dry asphalt rubber concrete (DARC) (i.e. a bituminous mixture with crumb rubber formed by a dry process). Such material is less known and investigated than the wet process, even if its application implies peculiar economic and environmental advantages such as no specialized equipment or significant plant modifications and a large quantity of recycled waste tires compared to the wet process. Different kinds of test are usually used in the experimental work such as bending tests or uni-axial tests, but they do not give the same answer. In the work, described in this paper, mechanical characterization was carried out by means of fatigue tests for asphalt material: a two point bending (2PB) test and four point bending (4PB) test, focused on the mechanical behaviour of DARCs with different rubber content by weight of the aggregates. Different strain controlled tests were undertaken for the same material under the same loading conditions, frequency and temperature (15Hz, 20 degrees centigrade), in particular an experimental survey was carried out in order to determine the stiffness modulus by means of the four point bending test on prismatic specimens (UNI EN 12697-26, 2004). This paper reports the experimental results for rubberized asphalt mechanical properties for a sub-ballast layer performed in a laboratory using the dry process.
The more and more frequent use of recycled materials within the road and railway infrastructures ... more The more and more frequent use of recycled materials within the road and railway infrastructures is now an irreversible trend. In this area the use of Dry Asphalt Rubber Concrete (DARC) in sub-ballast layer seems to be a suitable technique to reach high mechanical and environmental performance even if such material should be analyzed over a long time horizon. This paper presents the results of experimental research focused on the resistance to fatigue of Dry Asphalt Rubber Concrete in sub-ballast layers; the survey has been carried out using four-point bending test (4pbt) on mixture samples with different rubber contents. The results of fatigue in DARC have been compared with the performance of different mixes such as a standard hot mix asphalt without rubber and a rubber-modified asphalt concrete (RUMAC-Dry). It has been found that fatigue performance of Dry Asphalt Rubber Concrete is broadly comparable to other mixes, making it a very attractive material in terms of technical and economic skills.
The impact of temperature on the mechanical properties and thermal susceptibility of the railway ... more The impact of temperature on the mechanical properties and thermal susceptibility of the railway bituminous sub-ballast
layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average
seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather
situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment
of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle
size 0.2-4 mm) by weight of the total mix, as sub-ballast layer in railway and base layers on roads, recurring to the Superpave mix
design compaction enhanced after computer simulations to evaluate real stresses derived from the rail traffic and climatic conditions.
This article following the assessment of the average seasonal temperatures, involves the characterization of rubberized materials with
attention to crumb rubber properties, designed with dry technology, to enhance the bitumen-rubber and binder-voids ratios. Indirect
tensile strength and water sensitivity tests were applied for the evaluation of its mechanical properties including dynamic complex
modulus at elevated temperature to measure the amount of bitumen absorbed by the rubber. The rubberized mix-results obtained and
the comparison with a conventional HMA (hot mix asphalt) show that these dry rubber bituminous mixtures are particularly effective in
damping vibrations. The purpose of using rubber modifiers in hot mix asphalt to obtain a stiffer-elastic sustainable material has been
achieved for the assessment of its behavior in sub-ballast/base layers.
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Papers by Fernando MARTINEZ SOTO
SASW technique involves measurement of the time needed for an induced pulse to pass along the surface of the material.
The SASW method involves signal processing techniques similar to those used in the impact-echo (IE), impulse-response and free-free resonant column methods (FFRC), but information about the structure of the material, depth, change of thickness or different material used in the construction of the historical heritage is extracted through the profile of velocities generated by the series of superficial impacts made.
The speed of propagation is calculated according to the contact time of the impact, the broader the range of the frequencies or wavelengths, and the distance between the transducers. The Rayleigh wave velocity is related to Poisson’s ratio, material density, and dynamic material stiffness. The advantage of this technique is that only measurements in the surface area are needed, therefore simplifying the experimental setup.
The obtained results allow representing the wave dispersion curves of Rayleigh Wave, which can be used to infer the elastic properties of the underlying material.
In this study, we describe SASW surveys in the tambour and the dome of the Church of the San Justo y Pastor in Granada. The results obtained are in agreement with results found in the literature.
CITE AN ARTICLE
Soto, F. M., & Di Mino, G. (2018). “Improvements in the mix-design, performance features and rational methodology of rubber modified binders for the thermal evaluation of the railway sub-ballast”, (IJRSM/F09/17) International Journal of Research Science and Management, ISSN: 2349-5197, Volume 5, Issue 2, February 2018].
INTERNATIONAL JOURNAL OF ENGINEERING
SCIENCES & RESEARCH TECHNOLOGY, 7(1), 483-507.
DOI: 10.5281/zenodo.1158653
CItation: Martínez Soto, F. (2018) “Eco-Sustainable optimization of the mix-design methodology in modified bituminous mixtures with high percentage of recycled tire rubber,” (GJESRM/A008/18) Global Journal of Engineering Science and Research Management, ISSN: 2349-4506, DOI: 10.5281/zenodo.1156460 [Volume 5, Issue 1, Nº5, pp. 37-58, January 2018].
DOI: 10.5281/zenodo.1173468
benefits that it can provide. Indeed, it contributes to maintain the moisture content in the subgrade unchanged during all year. This
decreases the subgrade deterioration process. Moreover, the presence of bituminous sub-ballast can also reduce vertical stiffness
variations on the track; it can have a positive effect in the maintenance needs at transition sections (bridge-embankment) and in the
attenuation of the vibrations induced by the rail traffic. Despite the importance of the presence of the bituminous sub-ballast to conceive
the construction and/or rehabilitation of sustainable infrastructure, in literature, there are only fragmentary information regarding the
definition of benchmark criteria for their mix design. The superpave mix design approach used in road domain is applied systematically
in the railway domain, without being adjusted for different load configuration of the rail track system. This research work aims at
defining the benchmark criteria for the bituminous sub-ballast mix design to reduce the approximations involved in the recipe
optimization due to the limitation of applying the superpave system in the railway domain. The methodology proposed aims at selecting
the RESAL (rail equivalent single axle load) and therefore, transforming the entire traffic spectrum on the track lines in number of
ESALs. Afterwards, the Ndesign has been calculated as function of the rail traffic level. Finally, a case study of bituminous sub-ballast
mix design has been investigated for a first verification of the methodology proposed.
layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average
seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather
situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment
of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle
size 0.2-4 mm) by weight of the total mix, as sub-ballast layer in railway and base layers on roads, recurring to the Superpave mix
design compaction enhanced after computer simulations to evaluate real stresses derived from the rail traffic and climatic conditions.
This article following the assessment of the average seasonal temperatures, involves the characterization of rubberized materials with
attention to crumb rubber properties, designed with dry technology, to enhance the bitumen-rubber and binder-voids ratios. Indirect
tensile strength and water sensitivity tests were applied for the evaluation of its mechanical properties including dynamic complex
modulus at elevated temperature to measure the amount of bitumen absorbed by the rubber. The rubberized mix-results obtained and
the comparison with a conventional HMA (hot mix asphalt) show that these dry rubber bituminous mixtures are particularly effective in
damping vibrations. The purpose of using rubber modifiers in hot mix asphalt to obtain a stiffer-elastic sustainable material has been
achieved for the assessment of its behavior in sub-ballast/base layers.
SASW technique involves measurement of the time needed for an induced pulse to pass along the surface of the material.
The SASW method involves signal processing techniques similar to those used in the impact-echo (IE), impulse-response and free-free resonant column methods (FFRC), but information about the structure of the material, depth, change of thickness or different material used in the construction of the historical heritage is extracted through the profile of velocities generated by the series of superficial impacts made.
The speed of propagation is calculated according to the contact time of the impact, the broader the range of the frequencies or wavelengths, and the distance between the transducers. The Rayleigh wave velocity is related to Poisson’s ratio, material density, and dynamic material stiffness. The advantage of this technique is that only measurements in the surface area are needed, therefore simplifying the experimental setup.
The obtained results allow representing the wave dispersion curves of Rayleigh Wave, which can be used to infer the elastic properties of the underlying material.
In this study, we describe SASW surveys in the tambour and the dome of the Church of the San Justo y Pastor in Granada. The results obtained are in agreement with results found in the literature.
CITE AN ARTICLE
Soto, F. M., & Di Mino, G. (2018). “Improvements in the mix-design, performance features and rational methodology of rubber modified binders for the thermal evaluation of the railway sub-ballast”, (IJRSM/F09/17) International Journal of Research Science and Management, ISSN: 2349-5197, Volume 5, Issue 2, February 2018].
INTERNATIONAL JOURNAL OF ENGINEERING
SCIENCES & RESEARCH TECHNOLOGY, 7(1), 483-507.
DOI: 10.5281/zenodo.1158653
CItation: Martínez Soto, F. (2018) “Eco-Sustainable optimization of the mix-design methodology in modified bituminous mixtures with high percentage of recycled tire rubber,” (GJESRM/A008/18) Global Journal of Engineering Science and Research Management, ISSN: 2349-4506, DOI: 10.5281/zenodo.1156460 [Volume 5, Issue 1, Nº5, pp. 37-58, January 2018].
DOI: 10.5281/zenodo.1173468
benefits that it can provide. Indeed, it contributes to maintain the moisture content in the subgrade unchanged during all year. This
decreases the subgrade deterioration process. Moreover, the presence of bituminous sub-ballast can also reduce vertical stiffness
variations on the track; it can have a positive effect in the maintenance needs at transition sections (bridge-embankment) and in the
attenuation of the vibrations induced by the rail traffic. Despite the importance of the presence of the bituminous sub-ballast to conceive
the construction and/or rehabilitation of sustainable infrastructure, in literature, there are only fragmentary information regarding the
definition of benchmark criteria for their mix design. The superpave mix design approach used in road domain is applied systematically
in the railway domain, without being adjusted for different load configuration of the rail track system. This research work aims at
defining the benchmark criteria for the bituminous sub-ballast mix design to reduce the approximations involved in the recipe
optimization due to the limitation of applying the superpave system in the railway domain. The methodology proposed aims at selecting
the RESAL (rail equivalent single axle load) and therefore, transforming the entire traffic spectrum on the track lines in number of
ESALs. Afterwards, the Ndesign has been calculated as function of the rail traffic level. Finally, a case study of bituminous sub-ballast
mix design has been investigated for a first verification of the methodology proposed.
layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average
seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather
situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment
of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle
size 0.2-4 mm) by weight of the total mix, as sub-ballast layer in railway and base layers on roads, recurring to the Superpave mix
design compaction enhanced after computer simulations to evaluate real stresses derived from the rail traffic and climatic conditions.
This article following the assessment of the average seasonal temperatures, involves the characterization of rubberized materials with
attention to crumb rubber properties, designed with dry technology, to enhance the bitumen-rubber and binder-voids ratios. Indirect
tensile strength and water sensitivity tests were applied for the evaluation of its mechanical properties including dynamic complex
modulus at elevated temperature to measure the amount of bitumen absorbed by the rubber. The rubberized mix-results obtained and
the comparison with a conventional HMA (hot mix asphalt) show that these dry rubber bituminous mixtures are particularly effective in
damping vibrations. The purpose of using rubber modifiers in hot mix asphalt to obtain a stiffer-elastic sustainable material has been
achieved for the assessment of its behavior in sub-ballast/base layers.
Laboratory evaluation on the performance of hot mix asphalt (HMA) using recycled crumb rubber as an additive. Investigate optimal mechanical parameters of “aggregate-rubber” hot asphalt mixes with computer model development (KENTRACK). Searching on cost-effective materials with lower environmental impact and high preservation of the mechanical characteristics and performance.
Results: A new benchmark criteria for defining a first Superpave mix design system for railways. The scope is achieved with the evaluation of CRM-mixes as Plusride dry-gap-graded and dense-graded Generic-
Hybrid technologies. Mechanical parameters to develop a computer modelling in railway track sub-ballast.
General Assembly and Annual Conference of the Marie
Curie Alumni Association (24 to 25 March 2017, Salamanca,
Spain) entitled "Characterization of rubberized asphalt for railway sub-ballasts".
The use of recycled materials within the road and railway infrastructures
is now an irreversible trend. In this area, the use of Dry Rubber-modified asphalt concrete mixtures (RUMAC) in sub-ballast layer seems to be a suitable technique to reach high mechanical and environmental performance even if such material should be analysed over a long time horizon. This project presents the results of experimental research focused on the resistance to FATIGUE CRACKING of Dry Rubber-Modified Asphalt Concrete in sub-ballast layers; the survey has been carried out using 4-point bending tests.
The results of fatigue in rubberized asphalt in railways have been compared with the performance of different mixes such as a standard hot mix asphalt without rubber according to Italian standard, two PlusrideTM mixes with 1.5-3% crumb rubber modifier (CRM) and a Generic Hybrid-Dry modified asphalt concrete with coarse/fine scrap tire rubber.
Much research has been conducted in finding other alternative material to be used as a modifier in asphalt mixes to improve its properties. Rubberized asphalt mixtures are regarded as a proper solution for improving the strength of the rail-track section. In comparison with traditional granular sub-ballast, these materials allow an increase in bearing capacity and greater protection of the substructure.
The recycled rubber has become a great enhancer of the modified bituminous mixtures, and in this work, it has been shown as a sustainable improvement option in HMA mixes due to the elastic behavior exposed by the rubber particles especially in reducing the fatigue cracking potential.
This work presents a study of laboratory evaluation on the performance of hot mix asphalt (HMA) using recycled crumb rubber as an additive. In this context, the research, therefore, aims to study the use of sustainable bituminous sub-ballast manufactured from a waste material, which is recycled rubber produced from scrap tires at the end of their service life. To this end, the procedures developed in the Department of Civil Engineering of the University of Palermo during 2014 to 2017, is focused on evaluating the mechanical behavior of bituminous materials in comparison to that presented by conventional sub-ballast. Mechanical performance is examined concerning the main requirements that need these materials (resistance to bearing capacity, energy dissipation, fatigue-cracking strength and, waterproof properties) for their use in railway tracks.
Inside the SUP&R ITN project, enrolled as an ESR-8 fellow, the main purpose of this laboratory research is the application of ambient crumb rubber (0.2mm to 0.4mm) and ground rubber (2mm to 4mm) recycled from discarded truck tires. Crumb rubber modifier is processed at a conventional temperature (20 ºC) inside hot bituminous mixtures (160-220 ºC) as a substitute for 1.5%, 2% and 3% by weight of the total aggregates using the Volumetric Mix-Design.
El objetivo de este trabajo es el desarrollo de una técnica teórico-experimental para la monitorización no destructiva del comportamiento del hormigón durante el proceso de curado y ante desencofrados tempranos. La idea original del proyecto surge tras efectuar un análisis de problemas existentes en diversas obras civiles reales ejecutadas en los últimos años mediante encofrados móviles (viaductos mediante encofrado trepante, dovelas de túneles…), en las cuales no es posible establecer con fiabilidad intervalos de tiempos de hormigonado debido a factores ambientales, retraso en laboratorio, complejidades derivadas de la magnitud de las obras y la baja optimización del desencofrado, provocando un aumento de los plazos de ejecución. A la hora de proceder al desencofrado de un elemento hormigonado, es necesario verificar que la resistencia que posee el hormigón en ese momento es tal que permite retirar el encofrado sin que el elemento pierda la forma y sea capaz de soportar su peso y el de los elementos auxiliares de construcción. La técnica actual es realizar periódicamente ensayos de resistencia a compresión en probetas que deben mantenerse en las mismas condiciones de obra y en un número importante de especímenes, siendo muy difícil conseguir que se mantengan las condiciones ambientales a las que está sometido el hormigón, llegando a una resistencia a compresión que difiere de la real del hormigón colocado en la estructura. El estudio que se presenta en esta comunicación se basa en la técnica de análisis espectral de ondas superficiales (SASW en sus siglas en inglés) utilizada para determinar las propiedades de las distintas capas en un material estratificado. Esta técnica se basa en registrar las aceleraciones en dos puntos de la superficie del material ante una excitación impulsiva y calcular la velocidad de las ondas superficiales para diferentes frecuencias.
Como objetivo principal del trabajo se ha determinado la información necesaria de modelos estructurales de morteros dosificados de distinta forma (simulando perfiles heterogéneos y dispersivos debido a la diferente forma de curado de los especímenes), mediante el citado método de ensayo no destructivo de propagación de ondas superficiales [AEOS o SASW]: técnica idónea para definir directamente la curva de dispersión proporcionando la velocidad de onda superficial en función de la longitud de onda, variable valiosa dentro del perfil de capas de un material, ya que a través de este valor se derivan parámetros importantes estructurales (resistencias, módulos…) en morteros a edad temprana, presentando sus propiedades según proceso de curado, espesor y profundidad desde la superficie.
Conocido como método de caracterización no invasivo, desarrollado por Jones (1958) y evolucionado por Stokoe & Nazarian (1980) en geotecnia y pavimentos en su origen, hoy día, debido a sus posibilidades, se constituye como una alternativa significativa, más rápida, limpia y económica por su naturaleza no destructiva, en comparación a otras metodologías normalmente utilizadas.
La investigación se ha centrado principalmente en la aplicación de la teoría de propagación de la onda Rayleigh en un medio heterogéneo viscoelástico lineal basado en modelos reales tipo placa de morteros fabricados en laboratorio con diferentes dosificaciones para determinar mediante impactos a bajas frecuencias (alta longitud de onda y alcance en profundidad) la velocidad de onda en cada capa interna a diferentes edades de fraguado. Basado en el principio de que los diversos componentes de la longitud de onda en la superficie de impacto penetran a diferentes profundidades en un medio dispersivo de ondas R, las frecuencias de la onda se propagan a diferentes velocidades de fase.
Por tanto, se analizan y discuten las diferentes bases/etapas/resultados experimentales, del método explorando en detalle, su alcance, limitaciones, desarrollo computacional e implementación de la rutina como programa con aplicabilidad próxima a hormigones. Para validar el método los resultados se contrastaron con otras dos metodologías complementarias no destructivas, las técnicas de Frecuencia-Resonancia (FFRC) y de Impacto-Eco (IE).
ISBN: 978-613-9-81974-4
Editor: Dyviah Ramnatsing
Contributor : Fernando Martínez Soto