Thermal and acoustic properties of lime-based sustainable insulation materials produced from hemp fibers modified with boron

Abstract

The importance of using natural materials in the construction field within the framework of sustainable and environmentally friendly approaches is increasing day by day. In this context, this study was aimed to develop a hemp fiber-based insulating building material. The boron doped fibers were characterized by thermogravimetric and differential thermal analysis (DTA/TGA) and field emission environmental scanning electron microscopy (FE-ESEM). The materials were produced by mixing undoped, 10% and 15% boric acid doped hemp fibers separately with lime. The fiber:binder ratio was determined as 1:4 by weight in all samples. To determine the thermal and acoustic properties of the produced samples; thermal conductivity test with heat flow plate method, sound absorption and sound transmission loss tests with impedance tube method were carried out. In order to determine the mechanical strength of the materials, a three-point bending tests were performed. As a result of the analyses, the thermal conductivity coefficients of the samples produced using hemp fibers, which are undoped, doped with 10% and 15% boric acid solution, were determined as 0.0935, 0.1926, and 0.1863 W/mK, respectively; noise reduction coefficients (NRCs) were measured as 0.425, 0.443, and 0.385, respectively; the highest sound transmission loss values were recorded as 27.17, 33.50, and 46.92 dB, respectively; and the flexural strength (σ_f) values were determined as 1.922, 1.992, and 2.578 MPa, respectively.