Mechanical assessment of the induction heating as a method to accelerate the drying process of cold porous asphalt mixtures

Cold mix asphalts present clear advantages such as the fact that they do not need to be heated, what results in lower energy consumptions and emissions, or the possibility to be transported long distances and manufactured on an offsite. However, their use is highly limited due to the long curing times that are needed to reach their final strength and the lower mechanical performance achieved comparing to hot mix asphalts. This paper studies induction heating as a process to accelerate the drying time of the emulsion and compares it, in terms of the mixture mechanical performance, with a more conventional method in which the cold sample is heated up in an oven. Different tests, as Cantabro, stiffness and Indirect tensile strength have been carried out. The mechanical results have shown that the induction heating could be a feasible alternative to increase the initial strength and reduce the opening time for this type of layers, although more research is necessary concerning the optimization of the mixture and the improvement of the induction device configuration.This paper was financed by the Spanish Ministry of Economy and Competitiveness with funds from the State General Budget (PGE) and the European Regional Development Fund (ERDF) through the research project SIMA+ (Ref. BIA2016‐77372‐R)

Asphalt concrete mixture with recycled aggregates and modified bitumen at reduced temperature

The GREENROAD project was born to demonstrate a technically feasible alternative to conventional mixtures and to improve the sustainability of the road sector. The project involves the development of Asphalt Concrete mixture manufactured with steel slag of Electric Arc Furnace, which is produced in the region and currently implies a high environmental cost; RAP from other mixtures; and bitumen modified with end-of-life tyres. Besides, a wax has been used to decrease the manufacture temperature and improve the environmental impact. Finally, a mixture with more than 80% of recycled aggregates and with a decrease of temperature from 20°K to 30°K was achieved in laboratory, reaching the requirements for the maximum category of heavy traffic level (T00) of the Spanish specifications

Long-Term Simulation of a System for Catchment, Pre-treatment and Treatment (SCPT) of Polluted Runoff Water

The effects of pollutants in runoff on the environment have forced the development of several water treatment systems with the aim of reducing this kind of pollution before its final discharge. Nevertheless, many of these systems do not behave satisfactorily and, additionally, there is a low level of confidence in the treatment performance. This paper introduces the results of research on the long-term performance of a laboratory prototype of a System for Catchment, Pre-treatment and Treatment (SCPT) designed to deal with the polluted runoff water. Solid and oil treatment efficiency were the focus of the study. After fourteen consecutive simulated rain events, the treatment efficiency levels achieved by the prototype are higher than 80% of solids and 90% of oils

Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks

Interlocking Concrete Block Pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (RSL) and surface slope (SS). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25m2 for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the RSL and SS variables. All models passed a confidence level of 95%, presenting high R2 values and showing that RSL is a more influential variable than the SS for all clogging scenarios

Experimental study of bituminous mastic behaviour using different fillers based on the UCL Method

[EN]This research demonstrates that the use of suitable amounts of calcium hydroxide as an additive in asphalt mixtures can improve the aggregate-bitumen adhesion, forming a bituminous mixture which is more resistant to traffic loads and the action of water. The analysis was performed using the UCL method and the Cantabrian Test, taking as a case study three types of filler with different natures, mixed with 4.5% bitumen. The results are presented as state curves, which show clear differences between the three fillers, demonstrating that the hydroxide suffers small wear losses in concentrations close to 1.3%, indicating a significant reduction in the risk of plastic deformation, and an improvement in the mixture durability and/or adhesiveness

Laboratory Analysis of the System for Catchment, Pre-treatment and Treatment (SCPT) of Runoff from Impervious Pavements

This article reports the development and construction of a 1:1 scale laboratory prototype of a System for Catchment, Pre-treatment and Treatment (SCPT) of runoff polluted by contaminants washed from impervious pavements. The concept of the SCPT is an online system with an up-flow filter. The filter is composed geotextile layers and limestone. Laboratory tests carried out were focused on determining the SCPT prototype behaviour under different working conditions. The variables studied were: inflow, pollutant loads and filtration system configuration. The results show that the designed system has a high capacity for total solids and oil treatment, with an average efficiency of 85% and 97% respectively. Moreover, the regression equations of the treatment efficiency have been determined for each of the studied pollutants, for different inflow conditions and pollution loads

Long-term analysis of clogging and oil bio-degradation in a System of Catchment, Pre-treatment and Treatment (SCPT)

Runoff contamination has motivated the development of different systems for its treatment in order to decrease the pollutant load that is discharged into natural water bodies. In the long term, these systems may undergo operational problems. This paper presents the results obtained in a laboratory study with a 1:1 scale prototype of a System of Catchment, Pre-treatment and Treatment (SCPT) of runoff waters. The analysis aims to establish the operational behaviour of the SCPT in the long term with respect to oil degradation and hydraulic conductivity in the geotextile filter. It is concluded that bio-degradation processes take place inside the SCPT and that hydraulic conductivity of the geotextile filtration system decreases slowly with successive simulated runoff events

Estimación de la resistencia a compresión simple del jabre estabilizado “in situ” con cemento como material en la formación de explanadas de carreteras

Granite rock has powerful alterations at several meters of depth. The clayed sand resulting is commonly known as jabre. This “in situ” mixture of cement-stabilized soil requires a laboratory formula. Even when the test section is correctly verified, the mechanical properties of the homogeneous mixture of jabre exhibit high degrees of dispersion. The laboratory work undertaken included particle-size analysis and screening, defini­tion of liquid and plastic limits, compressive strength, dry density and moisture content over stabilized samples, modified Proctor, California Bearing Ratio (CBR) and the determination of the workability of the hydrauli­cally bound mixtures. The stress resistance curve was analyzed by means of a multilinear model of unconfined compressive strength (UCS). Since practical engineering only requires UCS for 7 days, in order to gain greater knowledge of the material, other UCS transformations were used at other curing times such as 7, 14 and 28 days.La roca granítica presenta habitualmente un horizonte de alteración con varios metros de potencia. La arena arcillosa resultante como producto de alteración se deno­mina comúnmente jabre. Aunque la fórmula de trabajo de la estabilización de jabre con cemento se verifique correctamente en tramos de prueba, la estabilización “in situ” del jabre con cemento presenta habitualmente elevadas dispersiones. Entre los ensayos de laboratorio efectuados se encuentran los ensayos de análisis granulo­métrico, límites de Atterberg, resistencia a compresión simple (RCS), la densidad y humedad sobre probetas de suelo estabilizado, Proctor modificado, índice CBR (California Bearing Ratio) y el plazo de trabajabilidad de la mezcla con cemento. La curva de endurecimiento del suelo estabilizado fue ajustada mediante un modelo multi­lineal. Aunque tradicionalmente se especifique la RCS a 7 días, buscando definir un mejor comportamiento del material, los autores calcularon otros modelos de jabre estabilizado para roturas a 7, 14 y 28 días

Optimization of Compaction Quality Control in the Core of Random Fillings within Linear Infrastructures: Application to Metamorphic Slate Fillings

The construction of random fillings from the excavation of medium hardness rocks, with high particle sizes, presents limitations in compaction control. This research applies new control techniques with revised test procedures in the construction of the random fillings core, which constitutes the main part of the embankment, with the bigger volume and provides the geotechnical stability to the infrastructure. The maximum thickness over each of the compacted layers researched that made up the random fillings was 800 mm. As there are many types of rocks, this research is applied to metamorphic slates. Quality control was carried out by applying new research associated with the revision of wheel impression test, topographic settlements, and plate bearing test (PBT). Thus, new test procedures are established, defining efficient thresholds. Comparisons make it possible to choose representative tests, avoiding duplication. The optimization of control reduces inspection times, ensuring quality adapted to the high construction efficiency of diggings. Traditionally, rocks were rejected due to their maximum size, underutilizing the use of high-quality materials. Promoting their utilization implies a better use of resources, and therefore, a higher environmental efficiency. A statistical analysis of the core of 16 slate random fillings was carried out, with a total of 2250 in situ determination of density and moisture content, 75 wheel impression tests, 75 topographic settlement controls, and 75 PBT. The strong associations found between different tests allowed to simplify the quality control