Optimization of microstructure of basalt-based fibers intended for improved thermal and acoustic insulations

Abstract

Batch compositions of basalt and dolomite were optimized to produce high-quality fibers and wool boards applying Cupola technology. The raw batches, cinders, single fibers and fabricated wool boards have been characterized using XRD, XRF, SEM-EDAX, μ-X-ray CT, Lambda meter, mechanical and acoustic testing procedures according to ASTM and EN standards. The CaO/MgO ratio, acidity, basicity and melting moduli of the basaltic cinders are mainly related to the basalt low content of Mg-bearing minerals (19.15 wt%). The single fibers diameter (8.60 μm), non-fibrous shots (13.00 wt%) and Al2O3 (14.08 wt%) contents together with the quasi-horizontal macrostructure (SL-C = 0.60) improve the wool boards compressive (14.29Kpa) and tensile (3.00Kpa) strength as well as point load (140.00 N) properties. The single fibers microchemistry shows their enrichment with thermal conductivity ceasing oxides (∑ = 65.02 wt%) which together with the average porosity (92.30%) enhance the thermal (32.43 mW/mK and 6.17m2K/W) and acoustic (1.00 αs and 1.05 NRC) wool board insulations. The fabricated wool boards mechanical, thermal, acoustic and fire insulation characteristics are improved 28.00-, 2.35-, 1.40- and 45.45-times greater than the adopted EN standards, respectively.