Examinando por Autor "Moreno, Rodrigo"

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    Effect of cellulose nanofibers on the rheological and mechanical properties of cement pastes with metakaolin and natural volcanic pozzolan
    (Elsevier, 2024-11-22) Rosa, Ángel de la; Ruiz, Gonzalo; Husillos-Rodríguez, Nuria; Moreno, Rodrigo
    This study investigates the influence of cellulose nanofibers (CNF) on the rheological and mechanical properties of Portland cement pastes with pozzolanic additions, focusing on compressive ductility. Unlike prior research that examines individual factors, this comprehensive analysis evaluates various parameters affecting CNF-enhanced pastes. Using commercially available CNF and two pozzolanic additions—metakaolin (MK) and natural volcanic pozzolan (NVP)—the study assesses mechanical and ultrasonic methods for CNF dispersion. CNF is added at 0%, 0.05%, and 0.5% by weight of cement (CEM). Results show distinct differences in flow curves and thixotropy, both with and without ultrasound. Compressive strength tests at 28 days reveal that 0.05% CNF is optimal for CEM ＋ MK pastes without ultrasound, outperforming Portland cement pastes with NVP. However, 0.5% CNF significantly improves compressive ductility in CEM and CEM + NVP pastes, despite reduced compressive strength. This study offers valuable insights into optimizing mechanical properties of CNF-modified pastes, enhancing the efficacy and sustainability of construction materials
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    Experimental study on quasi-static mixed mode fracture in self-compacting concrete with longitudinal reinforcement and steel fibers
    (Elsevier, 2025-02) Rosa, Ángel de la; Ruiz, Gonzalo; Moreno, Rodrigo
    This study investigates the mixed-mode fracture behavior of self-compacting concrete specimens reinforced with longitudinal steel bars and steel fibers. The experimental program involved three-point bending tests on asymmetrically notched prismatic specimens designed to induce and propagate mixed-mode cracks. The influence of different steel fiber dosages on crack initiation, propagation, and final failure was evaluated. Key findings reveal that the addition of steel fibers significantly enhances energy absorption and ductility under combined mode I and mode II fracture conditions. The results demonstrate the effectiveness of steel fibers in delaying brittle failure and improving the overall structural performance. Novelty lies in the combined use of self-compacting concrete and steel fibers to explore mixed-mode fracture mechanisms in reinforced elements