Synthesis of β-C2S-based binder from limestone and calcium silicate wastes
- 44 Downloads
The present paper deals with the preparation of eco-friendly and low-energy cementitious binders using industrial by-products or materials based on waste sludge from mining and washing of limestone. Supplementary raw material containing mainly tobermorite and xonotlite is the waste of calcium silicate materials used as porous filling material of acetylene gas cylinders. Mixtures of raw materials were calcined at temperature 1150 °C for 120 min. Hydration products were characterized by thermogravimetric analysis (TG/DTA) and by X-ray diffraction. The heat of hydration of binder was investigated by means of isothermal calorimeter. Other techniques, such as scanning electron microscopy, were also used to characterize the microstructure. The compressive strength of pastes cured standard conditions was lower than 5 MPa even during 90 days. After pre-curing during 2, 5 and 7 days, samples were submitted to the hydrothermal curing at 170 °C for 24 h. Samples developed much higher compressive strengths (30 MPa). The formation of α-C2SH and γ-C2S was observed in samples after autoclaving. Pre-curing duration and hydrothermal curing conditions significantly influence the performances of cementitious materials.
KeywordsLimestone sludge Belite cement γ-C2S Hydrothermal treatment
This paper was elaborated with the institutional support for long-term development of research organizations by the Ministry of Industry and Trade of the Czech Republic.
- 13.Lea FM. The chemistry of cement and concrete. London: Arnold; 1970.Google Scholar