Abstract:
The use of wet-shotcrete as an installation technique has become widespread worldwide due to its simplicity and benefits such as form-free and fast installation, minimum dust and rebound, short turnaround times and good thermo-mechanical properties. In recent years, colloidal silica bonded shotcrete castables have been used in different refractory applications combining faster and safer dry-out and superior refractory lining performance when compared to cement bonded castables. The development of high-performance shotcrete castables depends on several factors, including the use of suitable shotcrete accelerator. This study investigates the influence of different shotcrete accelerators, A (reference) and B (new develoment), on the installation characteristics and properties of a colloidal silica bonded refractory castable. An Al2O3-SiC-SiO2-C based sol-bonded castable was shotcreted using accelerator A or B and the refractory panels were characterized after drying and firing at different conditions. Results showed that accelerator B provided a smoother reaction with the silica sol binder, eliminating material pulsation during shotcreting, also improving the materials´ surface finishing. Although no substantial differences were noticed in the physical properties, a significant improvement in mechanical strength (MoR, CCS and HMoR) and abrasion resistance was observed when using accelerator B. Therefore, the choice of shotcrete accelerator can significantly influence the installation quality of sol-bonded refractory castables, positively impacting the installed material´s properties and enhancing the refractory lining performance.