Piumika W. Ariyadasa , Allan C. Manalo , Weena Lokuge , Vasantha Aravienthan , Andreas Gerdes , Jonas Kaltenbach
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引用次数: 0
Abstract
Alkali-activated geopolymers are increasingly studied as alternatives to Ordinary Portland Cement (OPC) concrete for use in challenging service environments. Low-calcium geopolymers have been advocated to mitigate Microbial-Induced Concrete Corrosion (MICC) in sewer pipes; however, their broader acceptance as a repair material for sewer rehabilitation remains to be established. This study evaluated the degradation mechanism of low-calcium fly ash-based geopolymer (FAGP) repair mortar under laboratory-simulated sewer conditions by exposing it to varying concentrations of sulphuric acid (pH 0.5, 1, and 4) for extended durations. The corrosion of the mortar samples was assessed based on visual changes, mass loss, residual mechanical strength, pore evolution, and ion transport over three exposure durations. Comparative analysis with OPC counterparts served as a benchmark. The degradation of FAGP and OPC due to acid exposure appears to escalate with both acid concentration and exposure. However, FAGP displayed superior performance by maintaining their shape and retaining approximately 30% of mechanical strength even after 3000 h of exposure under highly aggressive sewer conditions at pH 0.5. In contrast, OPC fails to endure acid exposure beyond 2000 h. The loss of matrix integrity primarily stems from ion leaching, supported by Scanning Electron Microscopy and Mercury Intrusion Porosimetry analysis, which revealed the creation of intrinsic pores facilitating the ingress of sulphate ions into the matrix. X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy patterns indicate no significant phase alterations, confirming this phenomenon. In conclusion, this study demonstrated that FAGP mortar is more resilient and durable in mild to aggressive sewer conditions than OPC.
期刊介绍:
Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.