Recycling ceramic industry wastes in sound absorbing materials

Abstract

ABSTRACT:The scope of this investigation is to develop a material mainly composed (80% w/w) of ceramic wastes that can be applied in the manufacture of road traffic noise reducing devices. The characterization of the product has been carried out attending to its acoustic, physical and mechanical properties, by measuring the sound absorption coefficient at normal incidence, the open void ratio, density and compressive strength. Since the sound absorbing behavior of a porous material is related to the size of the pores and the thickness of the specimen tested, the influence of the particle grain size of the ceramic waste and the thickness of the samples tested on the properties of the final product has been analyzed. The results obtained have been compared to a porous concrete made of crushed granite aggregate as a reference commercial material traditionally used in similar applications. Compositions with coarse particles showed greater sound absorption properties than compositions made with finer particles, besides presenting better sound absorption behavior than the reference porous concrete. Therefore, a ceramic waste-based porous concrete can be potentially recycled in the highway noise barriers field. RESUMEN:Reciclado de residuos cerámicos en materiales absorbentes acústicos. El objetivo de este trabajo es desarrollar un material absorbente acústico compuesto fundamentalmente por residuos cerámicos (80% p) que se pueda utilizar en la fabricación de dispositivos reductores de ruido de carretera. La caracterización del producto se ha llevado a cabo atendiendo a sus propiedades acústicas, físicas y mecánicas, determinando el coeficiente de absorción acústica a incidencia normal, porosidad abierta, densidad y resistencia a compresión. La absorción acústica de un material poroso está fuertemente determinada por el tamaño de poro y por la longitud dela probeta sometida a ensayo. De este modo, se ha analizado la influencia del tamaño de partícula del residuo cerámico y del espesor de las muestras estudiadas en las propiedades del producto final. Los resultados obtenidos se han comparado con los obtenidos para un hormigón poroso elaborado con árido grueso, que se ha tomado como producto de referencia tradicionalmente empleado en este tipo de aplicaciones. Las composiciones elaboradas con el residuo de mayor tamaño de partícula han mostrado mayor absorción acústica, incluso mayor que las del hormigón poroso comercial. Por tanto, un hormigón poroso elaborado con residuos cerámicos puede ser potencialmente empleado como material en la fabricación de barreras acústicas de carretera.PALABRAS CLAVE: Hormigón; Ladrillos; Tratamiento de residuos; Árido; Distribución de tamaño de partículas 2 • C. Arenas et al.

Morphological analysis of porosity and sound absorption in sustainable materials from rice husk

“…Compared to other studies with similar thicknesses with fibrous materials (kenaf, coconut, cane), the results are similar or higher, 2,8 and these materials have a higher NRC than that of granular materials made with waste. 38,45,46…”

“…Compared to other studies with similar thicknesses with fibrous materials (kenaf, coconut, cane), the results are similar or higher, 2,8 and these materials have a higher NRC than that of granular materials made with waste. 38,45,46 As the length of the specimen increases, the frequency at which the first maximum absorption peak is reached shifts to lower values and the number of peaks increases on the sound absorption curve. This is due to the fact that by increasing the length, the tortuosity of the channels is increased through which the sound wave circulates and rebounds, hence the expansion and contraction of air molecules in the absorber increases, thus increasing the dissipation of energy.…”

Experimental study of a noise reducing barrier made of fly ash

“…Other porous concretes with wastes have a compressive strength between 5 and 10 MPa (37). Flexural strength was higher than 0.6 MPa, the minimum level established for gypsum barriers (32), and higher than that of other porous concretes containing wastes (5,36). The addition of fibers increased flexural strength due to its bridge effect, but this did not have a significant influence on compressive strength (18).…”

Acoustic Performance of Porous Mortar and Potential Use for Traffic Noise Mitigation: A Review

“…A PM that has a high NRC alone is not sufficient because it is an indicator for the purpose of evaluating the material's ability up to 2000 Hz but the ability up to a medium frequency of 4000 Hz is also referred to assess the efficiency of a good material. Some PM is categorized as good because SAA exceeds 0.2 and has the potential to make it as one of the components in materials for sound absorbers [34][35]. Sufficient mechanical strength properties are also required which is a value of 2.8 N/mm 2 recommended by ACI 522R for porous concrete, but according to Arenas et.…”

“…For PM specimens with ceramic waste content (PM ceramic), although ceramic waste has a high density, the aggregate size range is larger and produces high porosity and NRC that is almost equivalent to BA and ACBFS which have a smaller aggregate size range but are highly porous due to the porous nature of the aggregate. For PM ceramic 1 (2-4.5 mm) and PMBA specimen (1.25-5 mm), the NRC is almost the same even though the porosity is slightly different, because the density of PM ceramic waste is lower due to the lower specific gravity of ceramic (2.15 g/cm 3 ) and the size larger aggregate creates larger pores compared to bottom ash even though it has a porous structure but has a higher specific gravity coupled with a range of stone sizes containing small sizes causing it to be denser [34][35]. For PM RP consisting of a mixture of 75% aggregate plastic instead of dune sand, porosity is said to be very low because plastic has a very low specific density (0.531-0.91 g/cm 3 ) and the opposite produces a low density compared to PM containing 100% dune sand.…”