Browsing by Author "Jin, Qingxu"

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    33
    (33, 33) Leon-Miquel, Matias; Silva-Retamal, Juan; Aparicio, Diego; Rangelov, Milena; Jin, Qingxu; Paul, Alvaro; 33
    This study aims to develop a novel solution to improve the sustainability and resiliency of the infrastructure in Chile. Due to the country's unique geographic situation of the coastal environment and high seismicity, the key is to design a low-carbon strain-hardening cementitious composite (SHCC) by replacing ordinary portland cement (OPC) with an abundant Chilean natural pozzolan (NP). The results indicate that the optimal replacement level is 30%. The newly developed NP-based SHCC shows a tensile strength of 6 MPa, a tensile strain capacity of 2.5%, and micro-cracks of <100 µm. In addition, this study also quantifies the environmental impact of the NP-based SHCC using a ‘cradle-to-gate’ life-cycle analysis. By replacing OPC with the NP, the CO2 emission of NP-based SHCC reduces by 23%. The excellent tensile properties and cracking control suggest that NP-based SHCC could contribute to developing sustainable and resilient Chilean infrastructure.
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    33
    (33, 33) Melo, Paula; Echagüe, Matías; Guerra, Carolina; Jin, Qingxu; Sancy, Mamié; Paul, Alvaro; 33
    To understand the effect of sulfate ions on the chloride-induced corrosion of reinforced concrete, this study focuses on the electrochemical behavior and surface analysis of standarded carbon steel that was exposed to simulated pore solutions, with different combinations of high and low chloride and sulfate concentrations. Linear scanning voltammetry and electrochemical impedance spectroscopy were used to monitor the corrosion reaction. Steel surface was characterized by X-ray photoelectron spectroscopy and field emission scanning electron microscopy. Results indicate that the presence of sulfate affects the electrochemical behavior of steel corrosion at a low and high chloride concentration, where the capability of the corrosion protective layer was influenced by the increase of the sulfate and chloride content. Calcium carbonate deposits were observed at the surface of corroded samples, where higher precipitation of calcium carbonate crystals on carbon steel surface is associated with higher rates of localized corrosion.
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    Crack sealers for the preservation of concrete bridge decks: a synthesis of a national survey and literature review
    Ni, Xiaoqiang; Leon-Miquel, Matias; Greiner, Quentin R.; Paul, Alvaro; Jin, Qingxu