Microstructure and Mechanical Performance of Belite Cements from High Calcium Coal Fly Ash

The microstructure and mechanical performance of two low energy fly ash belite cements (FABC‐1‐W and FABC‐1‐N) obtained from high calcium‐coal fly ash as raw material is studied in this work. The FABC were obtained after a previous hydrothermal treatment of the fly ash in demineralized water and NaOH 1 M solution. The hydration of both FABC‐1‐W and FABC‐1‐N during 180 days was followed by thermal analysis, X‐ray diffraction, FT infrared spectroscopy, scanning electron microscopy and Brunauer‐Emmett and Teller‐N 2 surface area measurements. The mechanical properties were studied under different curing conditions: normal (21°C and <95% RH) and accelerated (40°C and <95% RH). Porosity and pore‐size distribution were also studied. The results showed a better mechanical performance for FABC‐1‐N when the curing was normal and a better mechanical performance for FABC‐1‐W when the curing was accelerated.