Quartz-Based Castables with Calcium Silicate Cement as Binder-Mineralizer: Replacing Shaped Product for Large-Scale Fabrication

To meet the demand for intelligent masonry of large-sized silica bricks, calcium silicate cement synthesized from high-purity nano CaCO3 and microsilica was used as both binder and mineralizer in quartz-based castables. The effects of cement content (3−5 wt%) on performance were systematically investigated. With optimal retarder (0.015% citric acid monohydrate), the samples achieved early flexural and compressive strengths of 1.30 MPa and 7.0 MPa, respectively, after 24 h curing. During firing at 1430 °C for 20 h, CaO from cement effectively promoted quartz transformation to tridymite. Compared to conventional silica bricks, castables with 5% cement showed residual quartz below 1%, lower apparent porosity, over 2.5−fold higher cold crushing strength, comparable high-temperature creep, and superior refractoriness under load. This study demonstrates the dual gelling and mineralizing role of calcium silicate cement, offering a feasible route for producing large-sized quartz-based precast components.