Construction also focuses on the circular economy. Walls and floors insulated with recycled tires

Acoustic insulation, together with thermal insulation, are two fundamental pillars in modern building methodology, after decades of thermal compensations (hot and cold) in our homes, through the waste of a lot of energy, with the generation of pollution and after the impossibility to achieve comfortable acoustic privacy, correct controls have finally been created in line with the circular economy.

The construction technologies available to us, combined with the study of tested design models and precise regulations, has placed us in the conditions of being able to live in houses that have high thermal comfort , protecting us from the summer heat and the rigors of winter and consuming the as little energy as possible.

In addition, the refinement of the study on acoustics has allowed us to live in the city inside homes where the power to attenuate or cancel external noise, vehicular or airborne , is significant for high comfort within our lives.

It can be stressed that the design and use of sound absorbing or soundproofing barriers between housing units within condominiums has created an acoustic privacy that improves community livability.

Today, a further step has been taken, through the design and installation of acoustic insulators that match the indications of the circular economy, therefore using products that come from the recycling of materials at the end of their life.

This is the case of recycled tires , which are transformed into raw materials to be used in the production of mattresses, granulates and other products that can be used in the construction field, to improve the acoustic insulation of houses.

As already described in a previous article , the tires are collected and recycled by choosing between three different types of intervention:

Mechanical shredding

The process involves coarse shredding of tires with sizes around 70 or 100 mm. on each side, then going through the removal process of the metal parts, the granulation, with further cleaning and the final micronization process in which the product will be clean and divided into different particle sizes.

Cryogenic process

The process involves a first phase of coarse shredding of the tires with relative removal of the metal parts. Subsequently the ground is subjected to a cooling with liquid nitrogen, in order to recreate a crystalline and fragile structure that easily allows a new fine shredding. The resulting material is then treated through the pulverization process with hammer or disc mills.

Electro-thermal process

The process involves the first mechanical dimensional reduction of the product to then be inserted in vertical magnetic induction ovens. In these ovens the metal parts are detached from the rubber under the effect of a temperature of about 700 degrees. At the end of this operation, the rubber part is collected and sent for de-vulcanization which consists in returning the recovered element to a chemical form similar to the original elastomer, through thermochemical processes in autoclaves.

Among the three types of recycling, mechanical shredding is the one most widely used for the creation of a raw material suitable for the production of products for acoustic insulation.

The technical choice in the use of a soundproofing mat, made of recycled rubber, has many advantages, intrinsic in its properties:

•  High elasticity
•  Good impact resistance
•  Resistance to mold
•  Resistance to temperatures
•  Resistance to humidity
•  UV resistance
•  Acid resistance
•  Maintaining performance over time

The recycled raw material , based on the chosen particle size, is normally mixed with polyurethane resins and, subsequently, extruded in different thicknesses and densities depending on the type of intervention to be performed.

The surfaces of the rolls or sheets may have smooth, rough or embossed faces according to the type of sound absorption or required impedance.

The most common insulation products made with recycled rubber are:

•  Rolls or slabs for impact insulation between floors, to be incorporated into floor screeds.
•  Rolls or sheets to be inserted in the partition walls as mono or multilayer.
•  Mixtures in granules suitable for covering and insulating elements that are difficult to cover with preformed materials.
•  Antivibration bands to dampen the vibration phenomena of moving machinery or hydraulic systems.

The recycled rubber products are extremely malleable elements based on the type of construction required, therefore they are not only usable in new homes , but can also be easily used during renovation . In fact, they also go perfectly with plasterboard sheets for non-invasive interventions of acoustic separation.

Like other products on the market, the degree of sound absorption or impedance sound , is calculated within the construction package created, in fact, the insulating power is not calculated on the single element but on the sum of the performances, in the case of a wall , of the plasters , of the load-bearing elements, of the possible interspace and of the insulating element.

This also applies to the impact sound insulation value in which the acoustic performance is calculated considering the load-bearing structure of the floor, the screed, the insulating element and the final floor.

From an economic point of view , acoustic products made of recycled rubber are generally more expensive, for example, than polyethylene foam mattresses, but in the perspective of a circular economy, in construction specifications, elements that derive from recycling should always be preferred of waste , considering also that recycled rubber products, compared to other products on the market, maintain their characteristics unchanged over time without deteriorating performance.

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Automatic translation. We apologize for any inaccuracies. Original article in Italian.