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Evaluation of Setting Behavior in Slag‑based Geopolymer Concrete using Ultrasonic Pulse Velocity under Varying Mix Proportions | ||
| Civil Engineering and Applied Solutions | ||
| مقالات آماده انتشار، پذیرفته شده، انتشار آنلاین از تاریخ 01 مرداد 1404 | ||
| نوع مقاله: Original Article | ||
| شناسه دیجیتال (DOI): 10.22080/ceas.2025.29600.1023 | ||
| نویسنده | ||
| Nader Sabeti* | ||
| Department of Civil and Architectural Engineering, KTH Royal Institute of Technology, Stockholm, Sweden | ||
| تاریخ دریافت: 12 تیر 1404، تاریخ بازنگری: 31 تیر 1404، تاریخ پذیرش: 01 مرداد 1404 | ||
| چکیده | ||
| In response to the growing environmental crisis and the urgent need to curb carbon emissions and improve waste management, slag‑based geopolymer concrete has emerged as a low‑energy, sustainable alternative to ordinary Portland cement. This study investigates the initial and final setting behaviour of ground‑granulated blast‑furnace slag (GGBFS) geopolymer concrete using the ultrasonic pulse velocity (UPV) technique alongside a Freshcon mold system. Key variables examined include the molarity and type of alkaline activator, the alkali‑to‑slag ratio, and the proportion of slag within the concrete matrix. UPV traces delineate three distinct stages —induction (dormant), polymerization onset (activation), and network consolidation (hardening)—each typified by their signature “S‑shaped” profile. In this study, increasing the concentration of the alkaline activator and the proportion of ground granulated blast-furnace slag (GGBFS) was found to dramatically shorten both initia and final setting times of slag‑based geopolymer mixtures; however, beyond an optimal activator concentration and solution-to-slag ratio, these accelerating effects attenuate and polymerization kinetics become disrupted. Notably, whereas ordinary Portland cement exhibits an induction period in excess of 240 minutes, geopolymer samples activated at 6M complete their induction phase in under 30 minutes a 6–8 fold increase in initial setting rate. Such rapid setting, while advantageous for expediting placement cycles, poses challenges in mass concrete pours by heightening the risk of cold joints and imposing stringent formwork time constraints. Conversely, this accelerated hardening can be leveraged as a significant asset in future investigations into precast concrete elements and tunnel‑lining shotcrete applications. | ||
| کلیدواژه‌ها | ||
| Sustainable Development؛ Geopolymer concrete؛ Slag-Based binder؛ Setting time؛ Ultrasonic Pulse Velocity (UPV) method؛ Freshcon mold system | ||
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آمار تعداد مشاهده مقاله: 6 |
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