Vegetal Fiber Additives in Mortars: Experimental Characterization of Thermal and Acoustic Properties

Abstract

This paper investigates the influence of adding vegetal fibers on thermal and acoustic performance based on natural hydraulic lime. Mortar samples with 10% weight of vegetal fibers were fabricated adding water to obtain easily workable mortars with good consistency; their performance was compared to mortar samples without vegetal fibers. The fibers were of different types (rice husk, spelt bran, and Khorasan (turanicum) wheat chaff) and size (as-found and ground form). Thermal performance was measured with the Small Hot Box experimental apparatus. Thermal conductivity was reduced in the 1–11% range (with Khorasan wheat chaff and rice husk); no significant reduction was found with spelled bran in the mixture. When ground, fibers were characterized by both good thermal and acoustic absorption performance; a reduction of 6–22% in thermal conductivity λ was achieved with spelled bran (λ = 0.64 W/mK) and rice husks (λ = 0.53 W/mK), whereas the Khorasan wheat chaff had the highest sound absorption average index (0.38). However, the addition of fibers reduced sound insulation properties due to their low weight densities. This reduction was limited for rice husks (transmission loss value was only 2 dB lower than the reference).

Compressive and Thermal Properties of Non-Structural Lightweight Concrete Containing Industrial Byproduct Aggregates

“…It can be noted that the 10% addition of PET in the S-LWC+PET samples showed reductions of 33%, 32%, and 34% compared to the decreases of 32%, 31%, and 34% obtained for the D-LWC+PET samples with respect to the reference sample. In fact, the addition of PET increased the porosity of the material, thereby lowering density, and the porous cementitious materials had a lower thermal conductivity and sound absorption coefficient, as reported in other recent studies [ 78 , 90 , 91 ]. The density of the samples containing PET was reduced up to 15% on average in comparison with their counterparts without PET; see Table 7 .…”

The Challenge of Integrating Seismic and Energy Retrofitting of Buildings: An Opportunity for Sustainable Materials?

“…The incorporation of vegetal additives in mortars has been investigated by Quintaliani et al [77], with emphasis on the experimental characterization of the thermal and acoustic properties of such mixtures. More specifically, the study considered lime-based mortars incorporating rice husk, spelled bran and Khorasan wheat chaff in different sizes, which allowed them to achieve good thermal and acoustic performance.…”

Cellulose, Rice Husk and Polyvinyl Acetate-Based Composite: Flame Retardancy and Fungi Growth Experimental Study

“…Material thermal conductivity should not exceed 0.08 W/mK for insulation applications [6]. Some other relevant parameters include resistance to water vapor diffusion, water absorption, moisture content [7], low thermal transmittance (U in W/ m²K) [5], and adequate resistance to bending, tension [8], compression, fungal growth, and flame retardancy [9][10][11]; this last is referred to material's behavior 2 under fire conditions or fire-proofing property, while the mold growth test verify the effectiveness of adding borax or other element, in the decrease of fungal growth [12][13][14][15][16][17].…”