Table 2.

Characteristics of the samples tested for the determination of the intrinsic properties of the materials and maximum sound absorption coefficient (α) and the frequency, density and thickness of the specimens tested Arenas et al. (2017) [79]

Material	Particle size (mm)	Specimen code	Thickness	Density (kg m−3)	frequency	α
Bottom Ash	7 > Dp > 2.5	E2.1.1.1	40.30	765	1241	0.93
		E2.1.1.2	40.25	773	1278	0.93
		E2.1.1.3	80.55	780	1241	0.94
		E2.1.2.1	80.95	783	603	0.94
		E2.1.2.2	80.95	781	606	0.93
		E2.1.2.3	81.10	803	563	0.91
		E2.1.3.1	121.55	771	356	0.94
		E2.1.3.2	121.50	796	356	0.92
		E2.1.3.3	120.30	799	356	0.91
Bottom Ash	Dp < 2.5	E2.2.1.1	41.65	1242	106	0.50
		E2.2.1.2	41.30	1259	128	0.53
		E2.2.1.3	41.10	1236	106	0.45
		E2.2.2.1	82.20	1245	118	0.34
		E2.2.2.2	82.05	1263	97	0.34
		E2.2.2.3	81.90	1244	118	0.36
		E2.2.3.1	123.25	1250	128	0.27
		E2.2.3.2	122.70	1255	128	0.31
		E.2.2.3.3	122.35	1255	128	0.39