Performance and Micro-structure of Fired Bricks Made of Solidified Lake Silt

Abstract

Lake silt and solidified lake silt were used as the main raw materials to prepare fired brick samples employing the vacuum plastic extrusion in a laboratory scale study. Raw material properties tests showed that the addition of a small amount of solidified agent had limited influence on the plasticity index, oxide composition and mineral composition, but had some influence on the formability. Linear drying shrinkage, water absorption, bulk density, compressive strength, thermal conductivity and freeze-thaw resistance of two kinds of brick samples were tested. The test results showed that linear drying shrinkage of solidified silt brick samples with 90% solidified silt and 10% cinder was 5.42%, water absorption was 18.2% and compressive strength was 15.8 MPa. The overall performance of the fired brick samples made of solidified silt was slightly worse than that of the fired brick samples made of lake silt. In addition, SEM and MIP were used to examine the microstructural properties of brick samples, and the results demonstrated that the micro-structure of bricks made of solidified lake silt was more loose, and the porosity was higher than those of the bricks made of lake silt at the same dosage of cinder, which play an important role in the performance of the brick samples such as compressive strength and water absorption. Meanwhile, the thermal conductivity of the former was slightly lower, and freeze-thaw resistances of the both bricks were almost similar.

Keywords: lake silt,  solidified lake silt,  fired brick,  microstructure,  strength