Alexander López-González

La caracterización de propiedades físicas como el módulo de elasticidad y el de Poisson es fundamental para predecir el comportamiento mecánico de los materiales y optimizar el diseño estructural. El módulo de Poisson, en particular, presenta retos experimentales debido a que requiere alta precisión en la medición de pequeñas deformaciones. Este trabajo propone una metodología experimental para la determinación del módulo de Poisson en materiales de concreto mediante correlación digital de imágenes (DIC). Se elaboraron muestras cúbicas de dos diferentes diseños de mezclas de concreto. El arreglo experimental consiste en un sistema de aplicación de fuerza de compresión uniaxial y un sistema de medición de deformaciones basado en DIC. Este sistema monitorea simultáneamente las deformaciones en las direcciones axial y transversal, a partir de las cuales se calcula el módulo de Poisson. Los resultados muestran que esta metodología es una alternativa confiable para caracterizar esta propiedad mecánica del concreto mediante ensayos de compresión.

The ultrasonic pulse velocity (UPV) method is widely used for determining the dynamic modulus of elasticity of concrete. Traditionally, this approach requires assuming Poisson’s ratio (arbitrary values ranging from 0.1 to 0.25), regardless of the actual properties of the tested material. Such assumptions can lead to inaccurate estimations of the elastic modulus and limit the reliability of the method. In this study, an experimental methodology is proposed to enhance the accuracy of the estimation of the elastic modulus of concrete by combining digital image correlation (DIC) with UPV testing. The DIC technique is used during axial compression tests to directly measure the Poisson ratio of cubic concrete samples, while the dynamic modulus of elasticity is determined through UPV measurements. Subsequently, conversion models from the literature were applied to estimate the static modulus of elasticity from the dynamic modulus. The obtained values are compared with the experimental measurements of the static modulus, showing strong consistency and validating the proposed approach. The results highlight two key findings: (i) incorporating the actual Poisson ratio of the material significantly improves the precision of modulus predictions obtained via UPV, and (ii) DIC provides a reliable and adaptable tool for measuring Poisson’s ratio in concrete. Overall, the integration of DIC and UPV offers a robust and non-destructive framework for improving the assessment of mechanical properties of concrete.

This study evaluates the technical potential of using silica-rich mine tailings (MTs) as a partial substitute for Portland cement in concrete. The MT was characterized using particle size analysis, inductively coupled plasma optical emission spectrometry, X-ray fluorescence, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy, and sequential extraction. The material contained 25.01% silicon, 1.89% iron, and 0.21% calcium, with approximately 40% of particles smaller than 0.074 mm. XRD identified primarily quartz and moganite, two polymorphs of SiO ₂ , and nearly the unique source of Si. Mixtures were prepared with 0, 2.5, 5, 10, 15, and 20% replacement. At 60 days, the mixture with 2.5% substitution reached 37.17 MPa, compared with 30.06 MPa for the reference concrete, representing a 23.7% increase; the mixture with 5% substitution reached 35.88 MPa. In contrast, the 15% and 20% substitutions reduced the strength to 25.42 and 22.14 MPa, respectively. Chloride transport exceeded 4,000 C in all mixtures, classifying them as highly permeable. The mixture with 2.5% had a value of 8,616 C, compared to 8,350 C for the control, whereas the maximum value (10,645 C) was observed at 10% substitution. The 2.5% mixture exhibited the best overall performance under the conditions studied.

This paper presents a proposal for slabs reinforced with 3D steel reinforcements. Two configurations of 3D steel reinforcement, manually fabricated using 4 mm diameter rods, were investigated: cubic and square pyramid truss lattices. Two control groups were produced: a non-reinforced slab and a linear steel rod-reinforced slab. Three-point bending tests were conducted to assess the flexural behavior of the slabs. The results were analyzed in terms of flexural strength, peak load, mid-span displacement, energy absorption, crack formation, and ductility. The digital image correlation (DIC) technique was employed to capture the full-field principal strain and determine the mid-span displacement at the point of crack initiation. Furthermore, the compression capacity of each slab was evaluated. The results were compared with those of the non-reinforced and linear reinforced slabs, revealing that the slab with the cubic truss lattice configuration exhibited the highest bending moment capacity. While the square pyramid truss slab demonstrated relatively low bending strength, it exhibited exceptional energy absorption characteristics. In terms of ductility, the cubic truss-reinforced slab showed superior performance. When compared to the slabs with linear rod reinforcement, the 3D-reinforced slabs with cubic and square pyramid configurations enhanced the bending strength by approximately 51.19% and 47.32%, respectively. Overall, this study shows that the oblique connectors in the pyramidal reinforcement, compared to the vertical connectors in the cubic reinforcement, provide greater ductility and promote a more uniform distribution of smaller cracks, thereby enhancing energy absorption.

Los residuos mineros son considerados un riesgo ambiental y de salud debido a su alto potencial como generador de drenaje ácido además de la presencia de elementos potencialmente tóxicos (EPTs). En este trabajo se elaboraron probetas de concreto con sustituciones de cemento con jales mineros provenientes de la Presa Dos Carlos del estado de Hidalgo al 10, 20 y 30% en peso. Las muestras de jales se analizaron por diferentes metodologías como digestiones, pruebas químicas y potencial de neutralización para conocer las EPTs, sus propiedades y alcalinidad que tienen estos residuos. Las probetas de concreto se sometieron a pruebas de compresión para analizar su resistencia. Los resultados demostraron que estos residuos contienen Pb, As, Cr, Ag y Se, confirmando el riesgo latente en los jales mineros. Con respecto a la resistencia de las probetas con sustitución con jales al 10%, los resultados fueron satisfactorios en comparación con el 20 y 30%.

Se evaluó el desempeño de la influencia de la ceniza de bagazo de caña (CBC) como filler en mezclas de concreto autocompactante (CAC), adicionado en un 0%, 5%, 10%, 15%, 20% y 25% con respecto al peso de cemento. La caracterización de la ceniza se realizó mediante FTIR, FRX y DRX. Las propiedades de trabajabilidad del CAC fueron determinadas mediante ensayos de flujo de asentamiento, anillo J, caja en L, embudo V, Índice de Estabilidad Visual y resistencia a la compresión. De acuerdo con los resultados, los porcentajes de 10 al 20% en las mezclas de CAC obtuvieron un desempeño satisfactorio, evidenciando parámetros de trabajabilidad y resistencia a la compresión sobresalientes comparados con trabajos similares a los publicados en la literatura.