Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2023 (2)
Dokumenttyp
Sprache
- Englisch (2)
Schlagworte
- Calcium sulfoaluminate cement (2) (entfernen)
Organisationseinheit der BAM
Dredging sediment refers to materials removed from the bottom of a water body during dredging operations. Mainly the dreading mud contains clay, silt, sand, water, and alkalis. This work incorporated dredging mud into the calcium sulfoaluminate cement at replacement levels of 0%, 10%, 30%, and 50% by weight. Pastes were evaluated after 1d, 28d, and 90d- hydration through mechanical strengths and the reaction rate by isothermal conduction calorimetry. XRD and MIP characterized the reaction products. The findings showed that small replacements (10% and 30%) increased early strength with higher ettringite formation in the system at 1d of curing. However, the evolution of mechanical strength was lower than the reference (0% replacement) over time. The results showed that in low replacement dosages, the dredging mud act as a nucleation site for the hydration of calcium sulfoaluminate phases.
Binary systems composed of Portland cement (PC) and calcium sulfoaluminate (CSA) cement have stood out for applications requiring high early strengths. Nevertheless, the application of these systems may be limited due to their properties in the fresh state, which requires a better understanding of the rheological behavior of these materials. Thus, this study evaluated the incorporation of different polycarboxylate-based superplasticizer (SP) contents (0.15, 0.20, and 0.25 wt%) on PC and PC-CSA binary cement pastes. Rotational rheometry, isothermal calorimetry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption and desorption tests to assess the pore size distribution of cement pastes were conducted. While the SP incorporation reduced the dynamic yield stress of PC pastes, it progressively increased the yield stress of PC-CSA systems. The increase in SP content increased the main heat flow peak of PC-CSA pastes, although it did not significantly affect the cumulative heat after 160 h of hydration. FTIR and XRD confirm higher ettringite contents in the binary systems and indicate the presence of carboaluminates phases after 7 d of hydration in both PC and PC-CSA and hemicarboaluminate in PC-CSA pastes. The CSA incorporation reduced the cumulative pore volume by up to 32% compared to PC pastes, while the SP content evaluated did not significantly affect the porosity of PC-CSA pastes.