Due to the COVID-19 epidemic, biomedical waste management has overwhelmed both developed and developing nations. It is now a critical issue that has to be addressed with minimal possible adverse impact on the environment. This study introduced a technique of recycling face masks into polypropylene fibers for use in concrete. This proposed recycling process provides complete disinfection of contaminated clinical waste and offers the opportunity to transform the characteristics of an end product. Microfibers manufactured from recycled medical masks were subjected to testing. According to the results, polypropylene is the primary component of this research program. Two batches of concrete were made, one with the inclusion of masks as polypropylene fibers and another that performed as a control mix. The modified mortar was compared to the control mix in split tensile, flexure, compressive strength, and water absorption. Compressive strength was found to be improved by about 17%, and tensile strength to be increased by around 22% when mask fibers were incorporated. This research introduced a novel approach for disposing of waste masks and established the preliminary viability of upcycling trash face masks towards mortar concrete production.

The paper describes the application of the simple rotation‐free basic shell triangle (BST) to the non‐linear analysis of shell structures using an explicit dynamic formulation. The derivation of the BST element involving translational degrees of freedom only using a combined finite element–finite volume formulation is briefly presented. Details of the treatment of geometrical and material non linearities for the dynamic solution using an updated Lagrangian description and an hypoelastic constitutive law are given. The efficiency of the BST element for the non linear transient analysis of shells using an explicit dynamic integration scheme is shown in a number of examples of application including problems with frictional contact situations.

Las escorias de fundición de cobre son residuos industriales provenientes de la fundición del cobre las cuales procesadas en forma de granallas y sometidas a un proceso de molienda adquieren características similares a las de un árido fino. La presente investigación estudia la influencia que tiene su incorporación en el comportamiento mecánico a flexotracción y compresión en hormigones que emplean como árido fino una combinación de arenas del río Bío-Bío con proporciones de 25%, 40% y 50% en volumen de escorias de fundición de cobre. El árido fino resultante se utiliza en la confección de hormigones dosificados para relaciones de agua cemento de 0,45 y 0,52 asociadas a resistencias especificadas a la flexotracción de 3,6 y 4,3 MPa. Se mide la trabajabilidad en el hormigón fresco, la densidad, la carga de rotura por flexotracción y la carga de rotura por compresión en el hormigón endurecido comparando los resultados con un hormigón de referencia que no contiene escorias. Los resultados señalan que la docilidad de la mezcla se incrementa debido a la textura lisa de las escorias, se produce un aumento de la densidad del hormigón endurecido y las resistencias tanto a flexotracción como compresión se incrementan en función del contenido de escorias de fundición de cobre utilizado en la mezcla.

Chile’s reinforced concrete (RC) design is based on ACI 318-08, where high-strength reinforcement is not allowed in seismic force-resistant members. In 2019, new requirements adopted by ACI 318 permitted the incorporation of high-strength reinforcement in walls. This study compared the seismic performance of two Chilean 20-story residential buildings on soft soil, one designed with traditional Grade 60 and the other with high-strength Grade 80 reinforcement. The performance was assessed in terms of the probability of exceeding the ASCE 41 limit states during a 50-year lifecycle. Analyses showed that both buildings had similar seismic performance. However, the reduction in reinforcement in the Grade 80 building was close to 18%. It is concluded that using high-strength reinforcement in a typical wall building implies a significant reduction in the reinforcement used without affecting the seismic performance.