Evaluación de los parámetros de resistencia al corte de un material granular a partir de la inclusión de escorias negras de horno de arco eléctrico

Abstract

The present research aims to determine the influence of the physical characteristics of a granular material on its mechanical behavior. For this purpose, two materials were chosen: a non-plastic granular base MP and electric arc furnace black slag ENHAE. Based on physical characterization tests, Cu, Gs, emáx., and ρd. results were obtained for each material and their combinations, determining how the strength parameters are affected by the direct shear test under drained conditions. The experimental setup consists of fifteen (15) tests on standard samples and their respective inclusions, applying confinement stresses of 50 kPa, 100 kPa, and 200 kPa, with a cutting speed of 0.03 mm/min. Thus, a direct relationship was determined between the physical values of relative density (ρr) and the parameters of maximum shear strength (τ máx.), friction angle (φ´), and cohesion (C). To meet the objectives, the two materials were molded in their natural state in the laboratory; the first titled as the standard sample (MP) corresponds to a non-plastic granular material, the second being Electric Arc Furnace Black Slag (ENHAE) used as an addition. With the previously characterized materials, three mixes named MA, MB, and MC were prepared, replacing the granular material (MP) with ENHAE in proportions of 40%, 50%, and 60% of the retained weight in each sieve from No. 4 to pass 200. Both MP and ENHAE are well-graded non-plastic sands, type (SW) according to the USCS soil classification. The material for the standard sample (MP) was obtained from the Dromos Pavimentos S.A. quarry, located in the Los Puentes neighborhood in the municipality of Mosquera Cundinamarca, while ENHAE comes from the National Steel Company "Sidenal" located in the city of Sogamoso Boyacá. The base materials (MP and ENHAE) and their mixes (MA, MB, and MC) are compacted granular materials under optimal moisture, whose mechanical behavior depends on the fabric, characterized by the distribution of pore size PSD (Pore Size Distribution) and its suction component, which corresponds to a primary stress state variable to determine the stress-strain characteristics of a soil. Through the theory of partially saturated soils developed by (Bishop, 1959), (Fredlund, Rahardjo, & Fredlund, 2012), which relates matric suction and water content in the soil defined by the Soil Water Characteristic Curve (SWCC), the influence was determined to obtain the friction angle (φ'), cohesion (C), and dilatancy (φ) as resistance parameters. The samples of MP, ENHAE, and their mixes MA, MB, and MC were molded under the compaction energy of the Modified Proctor Test Method "A" (INV. E 142-13), aiming to determine the relationship between optimal moisture and maximum dry density. Additionally, tests were conducted using filter papers (INV. E-159-13) to determine the matric suction potential of partially saturated soil and obtain SWCC curves to establish stresses present in the soil mass. The results reveal that low air entry values "AEV" in the soil mass reduce the contribution of matric suction to shear strength parameters, friction angle (Φ'), and cohesion (C). Therefore, shear strength develops at the level of interparticle contacts generated during compaction under optimal moisture content and maximum density.