Fabrication of a Wall-Panel Board Using Rice Husk and Red Clay-Based Geopolymer

  • Johari M. Raki-in Mindanao Ceramic Development Center, Office of the Vice Chancellor for Research Extension and Development, Mindanao State University – Marawi, Marawi City, 9700 Philippines
  • Kenson Lovel M. Villagracia, Jr. Samaritan’s Purse International, Iligan City, 9200 Philippines
  • Ruben L. Menchavez College of Engineering and Technology, Mindanao State University – Iligan Institute of Technology, Iligan City, 9200 Philippines
Keywords: red clay, geopolymer, wall-panel board, alkali activator, thermal conductivity


This study fabricated a wall-panel board made of rice husk and red clay-based geopolymer. The geopolymer paste was studied at varying molarities of alkali-activator solution with a fixed ratio of Na2SiO3/NaOH at 2.5. A calcined red clay was used as the aluminosilicate precursor at a mass ratio of 1:1 to the activator solution. The geopolymer paste was heated at 80 °C for 12 h in a conventional oven and then aged for seven days at room condition. It was found out that 12 molars of NaOH in geopolymer paste provided the maximum flexural strength of 5.48 MPa. The rice husk was then introduced to the geopolymer paste at varying amounts from 10 to 20 wt% based on the mass of the paste. It was observed that the flexural strength and bulk density of the solidified composites decreased with an increasing amount of rice husks. Correspondingly, the measured flexural strengths varied from 4.21 to 3.13 MPa, whereas the bulk densities measured from 1.84 to 1.51 g/cm3. It was further observed that the addition of rice husks at 15 wt% in the geopolymer composite exhibited a lower thermal conductivity of 0.297 W/m-°K. The increased addition of rice husks above such amount negligibly decreased the thermal conductivity of the geopolymer composite. Lastly, the fabricated wall-panel board using the rice husk and red clay-based geopolymer is a promising lightweight and insulating material in the construction industry.