固化湖泊淤泥烧结砖的性能与微结构

以固化湖泊淤泥为主要原材料,采用真空挤压塑性成型技术制备并经烧结得到小样砖.对原材料进行理化性能分析发现,少量固化剂的加入并未明显改变淤泥的塑性指数、氧化物组成、矿物组成等,但对成型性能有一定的影响.测试并比较了湖泊淤泥、固化湖泊淤泥实验室小样砖坯体的干燥线性收缩、烧结后小样砖的体积密度、吸水率、强度、导热系数、抗冻性等.研究发现,当固化淤泥掺量为90%,煤渣掺量为10%时,可制备出坯体干燥线性收缩为5.42%,成品吸水率为18.2%,强度为15.8 MPa的小样砖,其综合性能较未经固化处理的湖泊淤泥烧结小样砖略差.采用SEM和MIP等测试手段对其微结构进行研究,结果表明,固化淤泥烧结小样砖与相同煤渣掺量的湖泊淤泥烧结小样砖相比,其微观结构更为疏松,未被玻璃相包裹的颗粒及未被填充的孔隙更多,孔隙率较大是导致其强度较低、吸水率较高的主要原因,但同时,其导热系数略低.2种烧结小样砖均具有好的抗冻性.

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

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.