Browsing by Autor "Romildo Dias Toledo Filho"

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Effect of adding fine glass waste on the mechanical properties of concrete in Cochabamba, bolivia
(IOP Publishing, 2025) Gustavo Condorcet Sevilla; Joaquín Humberto Aquino Rocha; Romildo Dias Toledo Filho
Abstract The management of glass waste presents a challenge in the construction sector, and its integration into concrete offers an innovative approach to waste valorization and sustainable materials development. This study explores the novel use of fine glass waste (FGW) as a mineral admixture, evaluating its impact on mechanical performance and durability at 2.5%, 5%, 7.5%, and 10% cement replacement levels. Results show that 5% FGW significantly enhanced compressive strength (28.62 MPa versus 21.45 MPa for the control) due to improved matrix densification, while higher dosages (≥7.5%) increased water absorption and void index, potentially affecting durability. A key innovation in this study is the detailed SEM-EDS microstructural analysis, which confirms FGW’s effective integration into the cement matrix but also identifies micropores at higher dosages, indicating potential durability concerns. These findings provide new insights into the controlled use of FGW in concrete, demonstrating its feasibility as a sustainable alternative while emphasizing the need for optimized incorporation to maintain durability. The study contributes to circular economy strategies by promoting glass waste repurposing in cementitious materials.
Effect of silica fume and water-to-binder ratio on workability, strength, and CO₂ emissions of cement pastes: A response surface methodology approach
(2026) Melissa Cindy Merino Llaves; Erick Alexander Torrez Real; Joel Gerson Peredo Villarroel; Hugo Nicolas Callao Corrales; Romildo Dias Toledo Filho; Joaquin Humberto Aquino
Normal- and high-strength concretes with eco-efficient cementitious materials: Proportioning and evaluation of physical, mechanical, and durability properties
(Elsevier BV, 2025) Joaquín Humberto Aquino Rocha; Nahúm Gamalier Cayo Chileno; Romildo Dias Toledo Filho
Use of recycled plastic bottle caps (RPBC) as partial sand replacement in cement mortars: Mechanical and CO₂ emissions assessment
(Elsevier BV, 2025) Joaquín Humberto Aquino Rocha; Ricardo César Solís; José Luis Martínez; Joel Gerson Peredo Villarroel; Victor Hugo Miranda Challapa; Jahel Sarvia Ledezma Perez; Nahúm Gamalier Cayo Chileno; Romildo Dias Toledo Filho
This study evaluates the use of recycled plastic bottle caps (RPBC), composed of high-density polyethylene (HDPE), as a partial replacement for natural sand in cement mortars. Mixes with varying RPBC contents (0 %, 10 %, 25 %, 50 %, 75 %, and 100 %) were developed to analyze their mechanical, microstructural, and environmental behavior. Tests included compressive strength, splitting tensile strength, and ultrasonic pulse velocity (UPV) at 7, 28, and 56 days, along with scanning electron microscopy (SEM) analysis. Additionally, CO₂ emissions associated with each mix were estimated, considering the material content and energy consumption during RPBC crushing, under two emission scenarios for sand. Results showed that incorporating up to 25 % RPBC does not significantly affect the mechanical properties of the mortar. However, a considerable decrease in mechanical performance was observed at replacement levels above 50 %, attributed to the low adhesion between recycled HDPE and the cementitious matrix, as well as its hydrophobic nature, which leads to increased porosity and a higher effective water-to-cement ratio. From an environmental standpoint, a progressive reduction in CO₂ emissions was observed with increasing RPBC content. Nevertheless, the eco-efficiency indicator (kg CO₂/(m³·MPa)) revealed that structural/environmental efficiency decreases for replacements above 50 %. The use of RPBC is technically and environmentally viable up to 25 %, offering a sustainable option for revalorizing plastic waste in construction.