The building sector has a huge environmental impact, and concrete, in particular, is a product that needs tremendous quantities of raw materials which are currently obtained from quarries with the huge impact this entails. Yet the steel industry has a considerable weight in the economy of the Basque Autonomous Community and generates large quantities of waste materials which frequently end up in landfills. That is why “the trend is that these materials that are generated should no longer be regarded as waste materials and should be used as raw materials to obtain other products,” said Alberto Esteban, researcher in the UPV/EHU’s Department of Mining and Metallurgical Engineering and Materials Science and who currently works at the company Eraiker-Gikesa.  

“This research seeks to contribute towards knowledge and improve the sound insulation of materials intended for the building sector by incorporating industrial waste, in particular steel works slag,” explained Alberto Esteban.

To do this, "firstly a new method has been developed to measure the soundproofing in small samples of different materials,” said the UPV/EHU researcher. Right now, “soundproofing tests are conducted using prototypes of 10m2  or with larger surface areas; this is a big constraint on the conducting of tests due not only to the difficulty in producing the volume of material that this involves but also to the actual economic cost associated with them,” added Esteban. The scale acoustic transmission chambers developed in this work considerably simplify and reduce the cost in the running of these tests, achieving results comparable with those of existing laboratories but using smaller test samples.

A scale laboratory

With the finely tuned, validated scale laboratory, the soundproofing performance of concrete plus steel aggregates and other industrial waste products to substitute natural quarry aggregates was assessed. The soundproofing performance of gypsum plus steelmaking aggregates as partial substitutes for gypsum and plaster were also evaluated.  

“The results allow one to confirm that the use of aggregates from electric arc furnace slag in concrete without actually achieving a clear improvement over the natural ones despite their greater density, do in fact achieve sufficient soundproofing performance that allows them to be used for construction purposes in line with current and future sound-proofing standards,” said Alberto Esteban.

In the case of gypsum, the UPV/EHU researcher stresses that “the incorporation of slag has a very positive effect in particular at low frequencies, in other words, bass sounds, and opens up a promising line of work while in fact improving one of the weakest points in gypsum-based systems”.

Additional information

This research was conducted within the framework of the PhD thesis by Alberto Esteban-González (Palma de Mallorca, 1974). It is entitled Estudio de las prestaciones acústicas de materiales de construcción que incorporen subproductos industrials (Study of the soundproofing performance of building materials that include industrial by-products) and was supervised by José Tomas San José-Lombera of the UPV/EHU’s Department of Mining and Metallurgical Engineering and Materials Science, and Milagros Losañez-González of Eraiker-Gikesa. The thesis was written up within the project of the Spanish Ministry of the Economy and Competitiveness “Bluecons: maximising the sustainable value of building materials and products by adding steel manufacturing by-products”.  For this purpose, work was carried out in collaboration with institutions such as the Department of Civil Engineering of the University of Burgos and the company ERAIKER/GIKESA, where the experimental part was carried out.