Influence of Pore Nature on the Thermal Conductivity of Insulating Refractory Brick

This work investigates the influence of pore nature on thermal conductivity of insulating refractory brick. The starting material used to compose the insulating bricks is kaolinite clay while saw dust of different grain sizes was used as combustible. Six sample batches of insulating brick were formulated with addition of fine saw dust particles (0 – 125 mm) and coarse saw dust particles (154 – 180 mm) at varying weight percent of 10, 25 and 50 respectively. The formulated samples were mixed with solution of sodium silicate dissolved in water as binder. The mixed samples were then pressed inside mould using hydraulic pressing machine under a load of 10 MPa. The pressed samples were left to dry at ambient temperature and later sintered in an electric muffle furnace at 1000 o C. Properties such as bulk density, porosity, thermal conductivity and morphology were investigated to assess the performance of the developed insulating bricks. The results showed that porosity increases with increase in amount of saw dust particles while the bulk density decreases. However, samples with fine saw dust particles exhibited higher porosity. In terms of thermal conductivity, samples with fine saw dust particles exhibited superior thermal value of less than 0.25 W/mK making them better suitable for insulation purpose. The morphology showed a well bonded structure of was dust within the clay matrix with several pores. Keywords: Pore size; Thermal conductivity, Kaolinite clay, Insulating brick DOI: 10.7176/CMR/12-7-03 Publication date: September 30 th 2020