Laboratory assessment of porous asphalt mixtures reinforced with synthetic fibers

Porous asphalt (PA) mixtures have become a new alternative in the development of new road pavement surface layers given their multiple advantages such as surface runoff improvement, the decrease of the urban heat island effect, the reduction of road traffic noise and the minimization of the spray and aquaplaning effect leading to a safer driving. However, the durability of these mixtures is not as good as for dense graded mixtures. This research studies the effectiveness of adding a blend of polyolefin/aramid fibers and homopolymer polyacrylonitrile fibers in PA mixtures in terms of functionality and mechanical performance. Furthermore, changes in the filler content are assessed. The experimental testing plan includes air voids characterization, permeability, moisture sensitivity and particle loss in dry and wet conditions. Improvements in the mechanical performance can be observed in dry conditions. Finally, the fracture energy, postcracking energy and toughness are also analyzed. The results show that the addition of fibers brings ductility to the PA mixture improving toughness while maintaining functionality since the air void content remains over 20%

Multi-Response Optimization of Porous Asphalt Mixtures Reinforced with Aramid and Polyolefin Fibers Employing the CRITIC-TOPSIS Based on Taguchi Methodology

For the optimum design of a Porous Asphalt (PA) mixture, different requirements in terms of functionality and durability have to be fulfilled. In this research, the influence of different control factors such as binder type, fiber content, and binder content were statistically investigated in terms of multiple responses such as total air voids, interconnected air voids, particle loss in dry conditions, particle loss in wet conditions, and binder drainage. The experiments were conducted based on a Taguchi L18 orthogonal array. The best parametric combination per each response was analyzed through signal to noise ratio values. Multiple regression models were employed to predict the responses of the experiments. As more than one response is obtained, a multi-objective optimization was performed by employing Criteria Importance through Criteria Inter-Correlation (CRITIC) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methodologies. The weights for the selection of the functional and mechanical performance criteria were derived from the CRITIC approach, whereas the ranking of the different experiments was obtained through the TOPSIS technique. According to the CRITIC-TOPSIS based Taguchi methodology, the optimal multiple-response was obtained for a polymer modified binder (PMB) with fiber and binder contents of 0.15% and 5.0%, respectively. In addition, good results were obtained when using a conventional 50/70 penetration grade binder with a 5.0% binder content and 0.05% fiber content.FORESEE project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 769373

Mechanical performance of fibers in hot mix asphalt: a review

The use of fibers in hot mix asphalt (HMA) has become a much more attractive alternative for the con-struction of road pavements. Numerous studies have shown that the incorporation of fibers in the mix-ture improves fatigue resistance, permanent deformation and stiffness. The aim of this paper is to presenta review of the mechanical impact of fibers in HMA by analyzing their reinforcement effect in a qualita-tive and quantitative manner. Fiber properties and characterization tests on fiber-modified bitumen arediscussed. Quantities, blending procedures and performance of bituminous mixtures with different typesof fibers are presented. Results of mechanical improvement are displayed. Based on the current researchresults, depending on the properties and the type of mixture in which they are used, each type of fiberseems to improve certain parameters more than others. Coconut fibers and waste fibers are describedas environmentally friendly alternatives

Influence of the diatomite specie on the peak and residual shear strength of the fine-grained soil

Diatomite is a powdering mineral mainly composed of diatom microfossils present in marine and lacustrine soils, which influences their physical and mechanical properties. Although many articles have been found in the literature concerning the influence of diatomite in the overall behavior of natural soils, few research efforts have been carried out to evaluate the influence of the diatom microfossil species on their shear resistance. Therefore, in this research, the influence of the diatomite species and the content in the peak and the residual shear strength of diatomite-fine grained soil mixtures was analyzed using the annular shear strength test. Scanning electron microscopy (SEM) and Atterberg limits were also carried out as additional tests to explain the interlocking effect between the microfossils and the soil. Overall, both diatomite species increased both peak and residual shear strength of the soil similar to dense sands. Nevertheless, the Mexican species reveal higher friction angle values compared with Colombian species

Evaluación mecánica de una mezcla asfáltica tibia (WMA) utilizando aditivos modificadores de viscosidad

La tecnología de mezcla asfáltica tibia (WMA) ha sido un incentivo en la industria asfáltica ya que contribuye a minimizar las emisiones de gases de efecto invernadero al medio ambiente, ayudando a reducir el calentamiento global y la huella de carbono. En esta investigación se evaluó experimentalmente el impacto de dos aditivos WMA sobre las características del ligante asfáltico y la mezcla asfáltica. Entre los resultados, se destacó el impacto de los aditivos en la propiedad de viscosidad del ligante asfáltico. Ambos aditivos redujeron la viscosidad a medida que aumentaba la temperatura en la mezcla. Con respecto a las mezclas asfálticas, la adición de aditivos wma tendió a aumentar la densidad aparente, los vacíos llenos de asfalto, la estabilidad Marshall y a reducir el contenido de vacíos de aire. La incorporación de estos aditivos puede reducir entre un 0.2 y un 0.4% el contenido óptimo de betún

Effect of Synthetic Fibers and Hydrated Lime in Porous Asphalt Mixture Using Multi-Criteria Decision-Making Techniques

Porous asphalt is a type of mixture characterized by having high air void percentages that offers multiple benefits when used in wearing courses in terms of driving safety, water flow management, and noise reduction. However, the durability of porous asphalt (PA) mixtures is significantly shorter when compared to dense-graded asphalt mixtures. This study investigated the impact of polyolefin-aramid fibers and hydrated lime in the functional and mechanical performance of porous asphalt mixtures. A parametric study based on the concept of design of experiments was carried out through the Taguchi methodology. Accordingly, an experimental design was conducted based on the L18 full factorial orthogonal array. Three control factors-fiber content, binder content, and filler type- were included at various levels, and multiple responses including total air voids, interconnected air voids, particle loss in dry conditions, particle loss in wet conditions, and binder drainage were assessed experimentally. Signal-to-noise ratios were calculated to determine the optimal solution levels for each control factor for the multiple responses. In the second phase of the research, multi-criteria decision-making techniques -namely, criteria importance through inter-criteria correlation and weighted aggregated sum product assessment- were used to transform the multiple-response optimization problem into a single-unique optimization problem and to elaborate a preference ranking among all the mixture designs. The most significant levels for acquiring the optimum overall response value were found to be 0.05% for fiber content and 5.00% for binder content and mixed filler with hydrated limeFunding: TheFORESEEproject has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No769373

Study of the effect of polyolefin-aramid fibers on PA mixture

The present research seeks to investigate the performance of a PA mixture reinforced with polyolefin-aramid fibers. The functional and mechanical performance of the mixture was assessed by different volumetric and mechanical tests including total air voids, interconnected air voids, Cantabro particle loss in dry and wet conditions and binder drainage test.This research is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 769373

Artificial reefs built by 3D printing: systematisation in the design, material selection and fabrication

The recovery of degraded marine coasts and the improvement of natural habitats are current issues of vital importance for the development of life, both marine and terrestrial. In this sense, the immersion of artificial reefs (ARs) in the marine environment is a way to stimulate the recovery of these damaged ecosystems. But it is necessary to have a multidisciplinary approach that analyses the materials, designs and construction process of artificial reefs in order to understand their true impact on the environment. For this reason, this paper presents the manufacture of artificial reefs by 3D printing, proposing designs with a combination of prismatic and random shapes, with different external overhangs as well as inner holes. For the definition of the artificial reef designs, criteria provided by marine biologists and the results obtained from a numerical simulation with ANSYS were taken into account, with which the stability of the artificial reefs on the seabed was analysed. Three dosages of cement mortars and three dosages of geopolymer mortars were studied as impression materials. The studies included determination of the rheological properties of the mortars, to define the printability, determination of the cost of the materials used, and determination of the mechanical strength and biological receptivity in prismatic specimens that were immersed in the sea for 3 months. To evaluate the environmental impact of the materials used in the production of the mortars, a Life Cycle Assessment (LCA) was carried out. In order to choose the mortars that encompassed the best properties studied, Multi-Criteria Decision Making (MCDM) was applied and the two best mortars were used for the manufacture of the artificial reefs. Finally, the advantages and disadvantages of the 3D printing process used were analysed. The results of the studies carried out in this research show that cement mortars have better characteristics for artificial reef applications using 3D printing, and that the technique applied for the manufacture of the artificial reefs allowed the digital models to be faithfully reproduced.This work has been co-financed by the European Regional Development Fund through the Interreg Atlantic Area Programme, under the project “Artificial Reef 3D Printing for Atlantic Area - 3DPARE” (EAPA_174/2016). Besides, the authors want to thank the following companies for their contribution: Solvay, for supplying the fly ash and sodium hydroxide; BASF, for providing the additives used in the research; Abonomar S.L., for providing the seashells sand; FCC ámbito, for providing the crushed recycled glass and Grupo Cementos Portland Valderribas (Mataporquera plant) for providing the cement

Evaluación experimental de mezclas asfálticas porosas reforzadas con fibras a través del diseño de experimentos integrado con análisis de toma de decisiones de criterios múltiples

RESUMEN: La mezcla asfáltica porosa se caracteriza por tener una alta porosidad permitiendo la descarga de agua a través de su estructura y suministrando múltiples beneficios en términos de la seguridad vial y el cuidado medioambiental. Sin embargo, su durabilidad es bastante baja en comparación con las mezclas asfálticas densas. Este estudio investigó el efecto de añadir fibras sintéticas en el comportamiento general de la mezcla PA utilizando una metodología innovadora que combina el concepto de diseño de experimentos (DOE) con el análisis de toma de decisiones de criterios múltiples (MCDM). Entre los resultados más relevantes, las fibras de poliacrilontitrilo (PAN) y el conjunto de fibras de aramida y poliolefina (POA) incrementan la resistencia a la abrasión y esfuerzo a tracción, especialmente en condiciones secas. A la escala del mortero, se observaron mejoras significativas a bajas temperaturas añadiendo fibras PAN y POA. En relación con el innovador método DOE-MCDM propuesto, las mezclas fabricadas con betún modificado con polímeros mostraron las primeras posiciones en la clasificación de las alternativas. Sin embargo, también se pueden obtener resultados admisibles usando un betún convencional con la proporción adecuada de fibras. La integración de las técnicas DOE y el análisis MCDM puede considerarse una herramienta poderosa para la evaluación del impacto de diferentes variables de control en múltiples respuestas.ABSTRACT: The porous asphalt (PA) mixture is characterized by having a large porosity allowing the discharge of water through its structure and providing multiple benefits in terms of road safety and environmental care. However, the durability is relatively lower in comparison to dense-graded asphalt mixtures. This study investigated the effect of adding synthetic fibers on the performance properties of PA mixtures employing an innovative methodology that combines the Design of Experiment (DOE) concept with the Multi-Criteria Decision-Making (MCDM) analysis. Among the most relevant results, polyacrylonitrile (PAN) and the set of polyolefin-aramid (POA) fibers increase the abrasion resistance, and tensile strength properties of PA mixture, especially in dry conditions. At the mortar scale, significant improvements were noticed at low temperatures adding PAN and POA fibers. Concerning the novel DOE-MCDM method proposed, mixes manufactured with polymer-modified binder (PMB) showed the first positions in the preference ranking. Nevertheless, admissible results can also be obtained using a conventional binder as long as the proper proportions of fibers are applied. The integration of DoE techniques and MCDM analysis can be considered a powerful tool for the evaluation of the impact of different control variables on different responses.Finally, note that the accomplishment of this thesis has been possible thanks to the projects “Fostering the implementation of fiber-reinforced asphalt mixtures by ensuring its safe, optimized and cost-efficient use (FIBRA) funded by the CEDR Transnational Road Research Programme - call 2017 under the contract N. 867481 and the FORESEE project that has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 769373. Scientific support from the consortium partners of both projects is gratefully acknowledged

Characterization parameters and mechanical response in diatomaceous soil depending on species

"Diatomaceous soil deposits around the world have become an special research focus considering some non conventional results (high values) related with shear strenght parameters, specially internal friction angle Q' (Diaz, 1992)(Cheng, 2007), even when there are high contents of organic matter or fine particles. The actual state of art report high values but do not determine the Diatom specie asswated with that result, and even less compare the results obtained in different places of the world specifying the native specie. This project tends preciselly to analyze the effect of speoe in previous mentioned parameters specially in those related with characterization, compressibility, shear strenght and load capacity... The investigation limits extended until two Diatoms species (Aulacoseira granulata Colombian ongin and the Centric Coscinodiscus Mexican ongin) tending to identify the variation in soil resistance parameters, behavior in the one dimensional Consolidation process, and even in the characterization criteria, based on species changes2. -- Tomado del resumen.Magíster en Ingeniería CivilMaestrí