Novel Foaming-Agent Free Insulating Geopolymer Based on Industrial Fly Ash and Rice Husk

This study highlights the synthesis of a new thermal insulating geopolymer based on the alkaline activation of fly ashes. A porous geopolymer material can be prepared without the addition of a foaming agent, using high ratio solution/ashes (activating solutions used are water, sodium or potassium hydroxide). In order to increase the porosity of the material and to make it more ecological, rice husks are incorporated into the formulation. The geopolymer materials were prepared at room temperature and dried at moderate temperature (105 degrees C) by a simple procedure. The microstructural characteristics of these new porous geopolymers were assessed by optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Infrared spectroscopy (FTIR) was used to confirm the geopolymerisation. The effect of the ratio solution/ashes and the percentage of the rice husk addition on thermal and mechanical analysis was evaluated. An insulating material for a solution/ashes ratio of 0.9 and a rice husk content of 15% having a lambda value of 0.087 W/(m center dot K), a porosity of 61.4% and an Rc value of 0.1 MPa was successfully prepared.

Automated summary

This study focuses on the synthesis of a new thermal insulating geopolymer using alkaline activation of fly ashes. The addition of foaming agents can be avoided by using a high ratio of solution/ashes. Rice husks are incorporated into the formulation to increase porosity and ecological sustainability. The microstructural characteristics of the geopolymers were analyzed using various techniques, and thermal and mechanical properties were evaluated based on different solution/ashes ratios and rice husk contents.