Browsing by Author "Silva Urrego, Yimmy Fernando"
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- ItemAdobe mixtures reinforced with fibrillated polypropylene fibers: Physical/mechanical/fracture/durability performance and its limits due to fiber clustering(2022) Burbano Garcia, Claudia Patricia; Silva Urrego, Yimmy Fernando; Araya Letelier, Gerardo AndresThis study assesses the feasibility of the incorporation of fibrillated polypropylene fibers (FPFs), an engineere multidimensional and multifilament fiber mostly used to reinforce concrete mixtures, into adobe mixtures (AMs), a traditional and manually-made material used to produce adobe blocks. The incorporation of FPFs was assessed using increasing dosages (0%, 0.25%, 0.5%, and 1% in wt% of clay soil) of FPFs. These fibers were gradually added and mixed with the clayey soil prior to incorporation of water to promote uniform mixtures with adequate fiber distribution to reduce the formation of fiber clusters. The impact of FPFs was evaluated in terms of its effects on the bulk density (physical), compressive and flexural strength (mechanical), flexural toughness indices (fracture) and water erosion resistance (durability) of AMs. Results indicate that increasing dosages of FPFs monotonically reduce average values of bulk density, as well as compressive and flexural strength of AMs. On the other hand, these increasing dosages of FPFs monotonically increase average values of water erosion resistance as well as flexural toughness indices, varying the flexural failure mode from brittle (unreinforced AM) to ductile (reinforced AMs) because of the adequate bonding and FPF-bridging effect after the crack generation as confirmed by instrumentation as well as digital image correlation evaluations implemented in this study. The significant reductions of bulk densities and compressive and flexural strengths obtained for fiber-reinforced AMs were related to the increasing number of fiber clusters found for increasing dosages of FPFs within the fiberreinforced mixtures, which was evaluated using scanning electron microscopy analyses. For example, positively the AM incorporating 1% of FPFs increased, on average, the flexural toughness by 674% and reduced the bulk density and water erosion depth by, on average, 9% and 64%, respectively, when compared to the unreinforced AM. However, this large dosage of FPFs also generated a significant reduction of the compressive strength (60% on average) and the flexural strength (43% on average) when compared to the plain mixture. On the other hand, a small dosage of FPFs (0.25%) generated less significant improvements in terms of flexural toughness, bulk density, and water erosion (on average, increment of 58% and reductions of 2% and of 38%, respectively, when compared to the unreinforced AM). Yet, the latter mixture presented reductions, on average, of compressive and flexural strengths of 24% and 16%, respectively, when compared to the plain mixture, and these reductions were significantly smaller than the reductions obtained by the largest FPF dosage, due to the significantly smaller number of fiber clusters presented by the 0.25% dosage when compared to the 1% dosage. Finally, the mechanical performance limitations exhibited by the incorporation of FPFs, especially in large dosages, are related to generated fiber clusters due to the inherent morphology of these FPFs as well as the traditional manual confection process of AMs. Therefore, this study recommends the implementation of FPFs in AMs, but in small dosages and/or suggests the implementation of a mechanical mixing/compaction process that guarantee a more uniform fiber distribution that reduces the generation of fiber clusters.
- ItemDurability of self-compacting concrete with addition of residue of masonry when exposed to carbonation and chlorides mediums(2021) Silva Urrego, Yimmy Fernando; Delvasto, SilvioThis research studies the durability of self compacting concrete (SCC) with residue of masonry (RM) taken from construction and demolition waste (CDW) as partial replacement of Ordinary Portland Cement (OPC). For this purpose, three concrete mixes each with a different percentage of RM (0, 25% and 50% by volume). A control mixture with 100% OPC content was used as reference specimen to compare other two mixes. The fresh properties of SCC mixtures were performed using tests for slump flow, T50 cm slump flow, V-Funnel flow time, and L Box. The strength and durability properties were evaluated using a compressive strength test, water absorption, porosity, sorptivity, accelerated and natural carbonation test, and rapid chloride penetration test (RCPT). Further Scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TG-DTG) tests were also conducted for microstructure analysis. The results showed that the use of RM in SCC mixtures does not affect the properties in the fresh state. In the hardened state, the compressive strength of SCC with 25% RM showed an improvement of 3.6% and 9.1% after 180 and 720 days of curing respectively compared to reference mixture. However, the durability properties such as resistance to carbonation, the use of RM in SCC mixtures resulted in increased carbonation in both the accelerated and natural carbonation tests. On the other hand, the SCC with RM showed a better behavior to chloride penetration, locating in the low permeability zone at 180 and 360 days according to ASTM C1202.
- ItemEfecto de tratamientos en agregados reciclados sobre las propiedades en estado fresco y endurecido de concretos autocompactantes(2022) Arcila Castro, Alejandro; Silva Urrego, Yimmy FernandoLa utilización de agregados reciclados provenientes de residuos de construcción y demolición (RCD) en nuevas obras civiles se considera el camino hacia la sostenibilidad. Esta investigación presenta la posibilidad del uso de agregado grueso reciclado (AGR) y agregado grueso tratado (AGT) de concreto en la elaboración de concretos autocompactantes (CAC). Para este propósito, dos métodos de tratamiento se realizaron a los AGR, uno de los tratamientos fue mediante desgaste mecánico en un molino de bolas y el otro fue mediante la inmersión en una solución acida (H2SO4) combinado con el desgaste mecánico. Para investigar el efecto de los AGR tratados sobre las propiedades mecánicas de los CACs, diferentes niveles de reemplazo (0%, 20% 40% y 100% en volumen) de agregado grueso natural (AGN) por AGR y AGT se realizaron. En estado fresco se evaluó capacidad de flujo, capacidad de paso y capacidad de llenado mediante el flujo de asentamiento con cono de Abrams, embudo en V y caja en L; y en estado endurecido se realizaron pruebas de resistencia a la compresión, tracción indirecta y flexión a los CACs. Los resultados muestran que los CAC con AGR presentaron una disminución en el desempeño de las propiedades en estado fresco y endurecido debido a la presencia del mortero adherido en este tipo de agregados, sin embargo, su trabajabilidad se encontró dentro de los parámetros establecidos por la EFNARC. Las propiedades mecánicas de los CAC con AGT presentaron un mejor desempeño en comparación a los CAC con AGR, debido al retiro del motero adherido mejorando la resistencia a la compresión todas las mezclas. Además, los CAC con AGT mostraron mejoras en las propiedades de permeabilidad presentando una reducción de porosidad de hasta un 6,06%.
- ItemExploring the Potential of Alternative Materials in Concrete Mixtures: Effect of Copper Slag on Mechanical Properties and Carbonation Resistance(2023) Silva Urrego, Yimmy Fernando; Villaquirán-Caicedo, Mónica A.; Izquierdo, SilviaIn this study, the effect on the flowability, compressive strength, absorption, sorptivity, and carbonation resistance of concrete with different copper slag (CS) replacement ratios was investigated. For this research, four concrete mixes with different percentages of CS were made (0%, 10%, 20%, and 30% of CS as replacement of cement by volume). In addition, the microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG–DTG). The results shows that the incorporation of CS reduces the workability and compressive strength of the mixtures, being more significant in concrete with 30% CS. The carbonation depth of concrete with CS increases monotonically with increasing CS. In addition, the compressive strength of the carbonated (20% and 30% CS) concretes show a loss of compressive strength at 90 days of exposure when compared to their water-cured counterparts. The use of low percentages of CS does not generate a decrease in workability and its mechanical effect is not significant at prolonged ages, so the use of this waste as SCM in percentages close to 10% is a viable alternative to the sustainability of concrete and the management of this residue.
- ItemPerformance of Self-Compacting Concrete with Residue of Masonry and Recycled Aggregate under Sulfate Attack(American Society of Civil Engineers, 2024) Silva Urrego, Yimmy Fernando; Delvasto, Silvio; Valencia, William; Araya Letelier, Gerardo AndrésThe use of byproducts as supplementary cementitious materials (SCMs) and recycled coarse aggregates (RCAs) can contribute tothe production of more sustainable self-compacting concrete (SCC) while modifying the durability properties of these mixtures. Thus, thisstudy addresses the combined use of concrete waste (CW) as RCA and residue of masonry (RM) as SCM, the CW and RM obtained fromconstruction and demolition waste, to generate SCC mixtures and to evaluate the performance of these mixtures under sulfate attack (5%Na2SO4and 5% MgSO4solutions). In detail, a reference SCC (M1) and three SCCs with 25% of RM and different level RCAs (0%, 50%, and100% replacement by volume) were cast. The hardened properties of the SCC mixtures were assessed in terms of compressive strength andsulfate attack. The results showed that the SCC mixtures with RM and RCA, cured in water, exhibited lower compressive strength results inall the evaluated ages compared with M1 (reference mixture, without RM and RCA). However, the SCC mixture with RM presented themaximum compression strength result among the different mixtures at 180 and 360 days. When mixtures were exposed to sulfate solutions,the SCC mixture with RM showed the best performance, and even the SCC mixtures with RM and RCA exhibited lower linear expansion andloss of compressive strength when compared with M1. The presence and severity of the sulfate attack were assessed via X-ray diffractionand scanning electron micrograph, which confirmed the presence of ettringite and gypsum in all the exposed SCC mixtures in the Na2SO4andMgSO4solutions.
- ItemShort and long-term physical and mechanical characterization of self-compacting concrete made with masonry and concrete residue(2021) Silva Urrego, Yimmy Fernando; Delvasto, Silvio; Izquierdo, Silvia; Araya Letelier, Gerardo AndrésThis study aims to investigate the fresh and hardened properties of self-compacting concrete (SCC) made with residue of masonry (RM) and concrete waste (CW). The RM was added as supplementary cementitious material (SCM), replacing ordinary Portland cement (OPC), in 25% by volume and the SCC mixtures were designed incorporating five increasing amounts of CW as recycled coarse aggregate (RCA) (0%, 25%, 50%, 75%, and 100%), which were compared with a reference SCC with a 100% OPC and natural coarse aggregate (NCA). Both fresh state (workability, passing ability and viscosity) and hardened state (compressive strength, indirect tensile strength, flexural strength, porosity and capillary suction) properties of SCCs were evaluated, including short and long-term evaluations. The results show that RCA generates a loss in the fluidity, flow rate, passing ability and filling capacity of SCC, presenting the greatest decrease of workability in high percentages (75% and 100%) of RCA. However, all the SCCs managed to be in the required ranges by the EFNARC. In the hardened state, the mechanical properties generally weakened with increasing replacements of RCA, but the reduction rate was minimal when the content of RCA did not exceed 50%, being 1.22% less at 360 days when compared to the reference mixture’s compressive strength. Finally, the presence of RM at long ages generated a positive effect on properties when compared to the reference SCC, which can be used to compensate the moderate strength reductions generated by low-to-medium replacement ratios of RCA leading to sustainable SCCs incorporating both residues (RM and CW) with similar performance than conventional SCCs.