Browsing by Author "Delvasto, Silvio"

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    Carbonation and chloride penetration performance of self-compacting concrete with masonry and concrete wastes
    (2024) Silva, Yimmy Fernando; Izquierdo, Silvia; Delvasto, Silvio; Araya-Letelier, Gerardo
    In this research, masonry and concrete construction and demolition wastes (CDWs) were used as supplementary cementitious material (25% vol. residue of masonry, RM) and recycled coarse aggregate (RCA) in increasing levels (0%, 50% and 100% vol. residue of concrete), respectively, in the development of self-compacting concrete (SCC). The performance of SCC mixtures was evaluated in terms of fresh properties, compressive strength, resistance to both accelerated (1% CO2, 65% R.H. and 23 degrees C temperature) and natural carbonation as well as chloride penetration. Experimental results showed a monotonic workability reduction associated to the incorporation of increasing levels of RCA. In compressive strength, the SCC with RCA showed the greatest increase in this mechanical property after 28 days of accelerated exposure in the carbonation chamber, when compared to its water-cured counterpart. Yet, at 360 days of accelerated carbonation exposure, all SCCs showed compressive strength reductions compared to their water-cured counterparts. On the other hand, the chloride permeability resistance of the SCCs was low and very low at the ages evaluated. Thus, the findings of this study indicate that the use of CDW can generate SCCs with adequate fresh properties, compressive strength and carbonation and chloride penetration performance, which offers benefits for the environment.
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    Durability of self-compacting concrete with addition of residue of masonry when exposed to carbonation and chlorides mediums
    (2021) Silva Urrego, Yimmy Fernando; Delvasto, Silvio
    This 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.
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    Performance 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 Andrés
    The 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.
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    Short 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 Andrés
    This 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.