Composite Materials of Rice Husk and Reed Fibers for Thermal Insulation Plates Using Sodium Silicate as a Binder

Abstract

The civil construction industry is responsible for a large part of the world’s energy consumption; therefore, in recent years, sustainable practices in this sector have become increasingly common to minimize the environmental impacts of civil construction during the life cycle of buildings. As a result, new materials and more sustainable building techniques are being sought. In Portugal, rice husk is an abundant agricultural waste with great potential to be used as a raw material in thermal insulation materials, as well as giant reed, which is considered an invasive plant. In this study, thermal insulation plates composed of rice husks and/or reed fiber were developed, using sodium silicate as a binder in various proportions and with dimensions of 30 × 30 × 3 cm and density ranging between 0.219 and 0.352 g/cm3. The main objective of the study is to evaluate the thermal characteristics of the plates, such as thermal conductivity, as well as the mechanical resistance to bending and water absorption. The results of the thermal conductivity tests were promising for all compositions, with values in the range between 0.0602 and 0.0745 W/m·K, meeting the requirements to be considered as thermal insulation materials. The results for bending strength and water absorption presented values within the expected range for materials of vegetal origin.