This systematic review presents the current state of research in the last five years on contaminants in soils, especially in leachates from solid waste landfills, with emphasis on biological remediation. In this work, the pollutants that can be treated by microorganisms and the results obtained worldwide were studied. All the data obtained were compiled, integrated, and analyzed by soil type, pollutant type, bacterial type, and the countries where these studies were carried out. This review provides reliable data on the contamination of soils worldwide, especially soils contaminated by leachate from municipal landfills. The extent of contamination, treatment objectives, site characteristics, cost, type of microorganisms to be used, and time must be considered when selecting a viable remediation strategy. The results of this study can help develop innovative and applicable methods for evaluating the overall contamination of soil with different contaminants and soil types. These findings can help develop innovative, applicable, and economically feasible methods for the sustainable management of contaminated soils, whether from landfill leachate or other soil types, to reduce or eliminate risk to the environment and human health, and to achieve greater greenery and functionality on the planet.

Reclaimed asphalt pavements (RAP) provide economic and environmental benefits. In recent decades, their use has increased, but rheological properties are affected by RAP aging, increasing stiffness, cracking, and susceptibility to water. To counteract these effects, rejuvenating agents are used, but they must be properly dosed to design quality mixtures. Therefore, different binders were analyzed, including virgin binder (VBB), binder modified by SBS polymer (MB), AC-RAP, binder softened using a rejuvenating agent, and binders softened with doses (15%, 30%, and 45%) of AC-RAP. The rheological properties were evaluated by dynamic shear rheometry (DSR) and beam-bending rheometry (BBR) tests, while the linear amplitude sweep (LAS) test was used to measure fatigue cracking and the multiple stress creep recovery (MSCR) test was used to measure rutting. A mixing chart was constructed based on a high temperature AC-RAP to satisfy the performance grade (PG 76-22). The results showed that softened binders become flexible, but when AC-RAP is added, they turn stiff and behave better than MB. Moreover, combining a rejuvenating agent and AC-RAP reduces the aging stiffness of RAP, improving its rheological properties without compromising the rutting or cracking resistance.

Mode I fracture (tensile type) is the common cracking mode of asphalt pavements, which is caused by thermal cyclic loading or traffic. Some studies allow the analysis of the fracture modes by means of standardized tests, some of which are limited, difficult, with little repeatability or do not generate an adequate tension state. In this paper, mode I fracture toughness of asphalt mixtures with symmetric geometry specimens at intermediate temperature is evaluated. Experimental results from direct tension test and simulations on asphalt mix specimens subjected to intermediate temperatures of 10, 20 and 30 °C, mode I load rates (0.5, 1 and 2 mm/min) and notches (2 and 3 cm) were compared to find the variables that reflect the operating conditions of the asphalt mix. Results showed that shear stresses are 8.12% lower in the simulations with respect to the tests, while the load-deformation curves show 30% and 35% variation, where the temperature of 20 °C, the notch of 2 cm and the loading speed of 1 mm/min are the conditions that best represent the stress state of the test; moreover, it manages to consider the elastic and viscous components of the material.

Ingeniería Investigación y Tecnología es una publicación trimestral, arbitrada, de investigación científica y tecnológica editada e impresa por la Facultad de Ingeniería de la UNAM. Su propósito es difundir información y conocimientos originales e inéditos relacionados con la ingeniería. Es un espacio para profesores, investigadores, profesionales y estudiantes de todo el mundo.

The Mexican asphalt paving industry is increasingly interested in using reclaimed asphalt pavement (RAP) to produce hot mix asphalt (HMA) due to its economic and environmental advantages. However, an ill-defined methodology for integrating RAP into the HMA mix design has hindered its use. This paper investigates how compaction energy affects both rejuvenated and non-rejuvenated recycled HMA mixtures. A Superpave gyratory compactor was used to determine the optimal binder content and find a balance between flexibility and stiffness that meets cracking and rutting resistance requirements. Various recycled HMA mixtures were subjected to different compaction energy levels (75, 100, and 125 gyros), different RAP contents (15%, 30%, and 45%), and various dosages (10%, 15%, and 36%) of the rejuvenating additive Maro-1000^®, following the blending chart. Performance was evaluated using the Hamburg wheel tracking test (HWTT) and the fracture energy flexibility index test (I-FIT). The results demonstrate that mixtures with RAP, a rejuvenating admixture, and varying compaction energies exhibit favorable mechanical behavior. However, both rejuvenated and non-rejuvenated mixes with 15% RAP showed performance comparable to conventional mixtures. They improved stiffness by up to 46% while reducing the flexibility index to 25%, striking a balanced equilibrium between rutting resistance and cracking susceptibility.

Actualmente, se están desarrollando técnicas y procedimientos para lograr diseños de mezclas asfálticas capaz de soportar altos niveles de tránsito mediante el mejoramiento del desempeño del pavimento, por lo que el objetivo de este estudio es lograr una mezcla que cumpla con las especificaciones de agrietamiento y deformación permanente utilizando una menor cantidad de cemento asfáltico, además de utilizar una mayor cantidad de pavimento asfáltico recuperado (RAP) mediante la implementación de una nueva metodología denominada Diseño Balanceado de Mezcla Asfáltica (BMD), el cual dentro de sus requerimientos evalúa el rendimiento de la mezcla en cuanto a la deformación permanente y el agrietamiento, dando un parámetro del porcentaje máximo y mínimo de contenido asfáltico que podría utilizarse en la mezcla. Para ello se ensayaron tres mezclas con diferentes porcentajes de asfalto, la primera con el óptimo (5%) obtenido mediante el análisis volumétrico Superpave, la segunda con una menor cantidad de asfalto (4.5%) y la tercera con un porcentaje mayor (5.5%), dando como resultado un rango de asfalto aceptable entre 4.8 y 4.95% cumpliendo con los parámetros evaluados. Además, se ensayaron cuatro mezclas combinados con 30% de RAP y con diferentes porcentajes de asfalto, la primera con el óptimo (4.65%), las tres siguientes con porcentajes mayores (5.15, 5.65 y 6.15%) dando como resultado el cumplimiento en el ensayo de deformación permanente, sin embargo, en el ensayo de agrietamiento resultaron ligeramente por debajo del mínimo recomendado, por otra parte, cabe mencionar que a las mezclas combinadas con RAP no se le agregó ningún aditivo rejuvenecedor, únicamente se utilizó un asfalto PG 64-22-H. Es importante mencionar que, para el diseño virgen, se logró disminuir el porcentaje de asfalto utilizado en la mezcla, contribuyendo en la optimización del costo y del uso de cementos asfálticos.