High-performance aggregate production by sintering terra rossa containing pyrophyllite and colloidal calcite

The demand for high-performance lightweight concrete in the construction industry has increased the need for higher-strength and lightweight aggregates compared to existing aggregates. Terra rossa (TR) containing pyrophyllite and colloidal-sized calcite was evaluated as a raw material in the production of aggregate. Small cylinders (15 x 15 mm) were prepared with (TR) to investigate the effect of water content, molding force, drying time, and different sintering temperatures on the physical, mechanical, mineralogical properties and microstructure of aggregates. According to SEM observations, increasing the molding force considerably decreased the porosity and the amount of partially bonded grains. The highest aggregate strength (145 MPa) was obtained for 15% water content, 27 kN molding force, and sintering at 900 & DEG;C in aggregate production. The particle density was 2.04 g/cm(3), while it was 2.22 and 2.38 for 1000 and 1100 & DEG;C. Colloidal size calcite helped to reduce the particle density by forming pores thanks to gas generation. The glassy phase formed in the body more than necessary decreased the strength (82 MPa) due to the brittle structure at 1000 & DEG;C. The mullite phase developed at 1100 & DEG;C with the aid of pyrophyllite enhanced the aggregate strength up to 117 MPa. The performance of sintered TR aggregate in concrete can be investigated within the scope of future studies.

Automated summary

The effect of water content, molding force, drying time, and different sintering temperatures on the physical, mechanical, mineralogical properties and microstructure of aggregates produced with terra rossa (TR) containing pyrophyllite and colloidal-sized calcite were investigated. Increasing the molding force significantly reduced the porosity and partially bonded grains in the aggregates. The highest aggregate strength (145 MPa) was obtained with 15% water content, 27 kN molding force, and sintering at 900°C.