In the rehabilitation of flexible pavements with asphalt layers, it is necessary to apply a bituminous tack coat with a pre-established dosage, which usually does not take into account the degree of texture generated if a milling operation is previously performed since this increases the surface at the interface. On the other hand, when milling, grooves are obtained that could lead to the runoff of bitumen emulsion with excessive deposition in their valleys due to dosages greater than those needed. This work analyses the above mentioned and achieves a compromise solution, with its corresponding method of application, based on the mechanical behaviour obtained with different degrees of texture and validated for typical materials used in Argentina.

Los neumáticos desechados a diario generan un pasivo ambiental importante, siendo acumuladores de agua que atraen infecciones como el dengue y a su vez tienen altos tiempos de degradación que los convierte en un material potencialmente inflamable. Sin embargo, con el correcto tratamiento del caucho que contiene y su trituración en diversos tamaños, se consiguen múltiples aplicaciones como elementos de demarcación vial, pisos de anti-trauma y de seguridad, accesorios para ejercitar, relleno de césped artificial, entre otros. El de mayor proyección en el último tiempo, es la incorporación del caucho en polvo de neumático fuera de uso (NFU) como modificador de mezclas asfálticas aumentando las propiedades de carpetas de rodamiento convencional, obteniendo un material con un desempeño acorde a las exigencias de las altas demandas de tránsito. Con la incorporación del NFU se retira del medioam-biente dicho desecho, dándole una segunda vida útil como modificador del asfalto y reduciendo la huella de carbono. Para satisfacer la demanda de NFU se debe proponer la implementación de un sistema de recolección de neumáticos que involucre municipalidades, agrupaciones sociales y otras entidades para proveer el material a las empresas productoras de polvo de NFU.

Asphalt binders are among the most widely used non-renewable resources in the construction, maintenance and operation of road infrastructure. This has intensified the search for alternative materials capable of partially replacing bitumen, encouraging research into renewable resources and industrial residues as more sustainable options. This study evaluates the maximum practical incorporation of lignin as a partial bitumen substitute, with emphasis on lignin recovered from black liquor waste (LBL) from a Peruvian paper-industry plant. An 85/100 penetration-grade binder was partially replaced with commercial lignin (CL) and LBL, selecting dosages of 10% CL and 8.5% LBL by binder mass as the most stable incorporation levels capable of upgrading performance towards behaviour comparable to 60/70-grade bitumen. Binder testing (rotational viscosity, DSR/RTFO, MSCR and BBR) and mixture performance evaluation (volumetrics, moisture susceptibility, Hamburg wheel-tracking, dynamic modulus and IDEAL-CT) were conducted. CL improved high-temperature rutting resistance and achieved a higher MSCR traffic grade (“E”), whereas LBL met specification requirements with a grade comparable to the control (“V”). All mixtures satisfied volumetric criteria and achieved TSR values above 0.80, with rutting performance remaining within the acceptance criterion. Dynamic modulus master-curve analysis indicated that LBL exhibits lower mixture stiffness at elevated temperatures than the control, consistent with its higher rutting susceptibility. Although IDEAL-CT results showed reduced cracking tolerance in lignin-containing mixtures relative to the control, overall the findings demonstrate the technical feasibility of valorising black-liquor-recovered lignin as a partial bitumen replacement in asphalt mixture design.