Calcined cutter soil mixing residue-based alkali-activated cement: Compressive strengths, reaction products, and sustainability

This paper presents a feasibility study on developing sustainable alkali-activated cement with calcined cutter soil mixing residue (CSMR). CSMR is a solid waste mainly consisting of cemented soil generated from ground improvement and currently ends up in a landfill. Alkali-activated calcined CSMR (AA-CSMR) specimens were prepared and tested. The test variables included silicate modulus (Ms) and alkali dosage of activators, curing regimes, as well as the incorporation of slag. The alkaline activation products were characterized using X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Results demonstrate that ambient-cured AA-CSMR cement shows rapid early strength development and achieves a maximum 28-day compressive strength of 33.2 MPa, which can even be increased to 50 MPa or higher by either incorporating 10% ground blast furnace slag or 1-day curing at 70 °C. The primary reaction products of the AA-CSMR cement are C–(A)–S–H gels, which could be traced back to the reactive calcium-rich amorphous phases formed in the CSMR by the calcination. Ecological parameters demonstrate that in comparison to the ordinary Portland cement, the AA-CSMR cements save around 60% and 70% embodied energy and CO2 emissions, respectively.

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