SOUND ABSORBING CASE HISTORY. Anti reverberation, sound absorbing plaster on the motorway section of the A1 at Casalecchio di Reno

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1 Anti reverberation, sound absorbing plaster on the motorway section of the A1 at Casalecchio di Reno SOUND ABSORBING CASE HISTORY 03

2 Anti reverberation, sound absorbing plaster Anti reverberation, sound absorbing plaster on the motorway section of the A1 at Casalecchio di Reno Work site Name Section of A1 Motorway Lotto 0

2 2 Anti reverberation, sound absorbing plaster Anti reverberation, sound absorbing plaster on the motorway section of the A1 at Casalecchio di Reno Work site Name Section of A1 Motorway Lotto 0 Casalecchio di Ren Year 2009 Customer Autostrade Spa Contractor Impresa Spa Place Casalecchio di Reno Work Duration 10 days Number of labourers 2 teams Surface area 700 mq Plaster thickness 4-5 cm Description of the operation The operation was carried out on a concrete curtain, 6m high, on the A1 motorway, that divides the North Lane from the South Lane at a point in which it goes through a tunnel that cuts through the side of a hill. The Concrete Curtain, which is the outer wall of the tunnel towards the south lane, was extremely smooth and reflective, so much so as to create a serious problem of sound reverberation that was disturbing to the inhabitants of nearby Casalecchio di Reno. The Problem The customer requested the intervention as a precautionary measure to avoid any possible future litigation regarding the noise generated by the continuous traffic that is particularly heavy on the section of the motorway. Instead of using the Cantilever noise barrier panels as is normal in these types of situations, because of insufficient space and various safety issues it was decided to opt for the Sound absorbing Plaster Diathonite Premix.

Anti reverberation, sound absorbing plaster 3 Amongst the many advantages of a sound absorbing plaster, 2 in particular determined the final choice: the complete absence of dangerous debris in the

3 Anti reverberation, sound absorbing plaster 3 Amongst the many advantages of a sound absorbing plaster, 2 in particular determined the final choice: the complete absence of dangerous debris in the case of a motor accident or impact and the extreme ease at which it can be repaired following any eventual accident by use of the platforms that can be lowered from the ceiling of the tunnel, without any need to close the roads. The technical solution Creation of adhesion bridges on the concrete curtain using Aquabond primer Application of Diathonite Premix in 3 layers until reaching the required 5 cm thickness Application of a waterproofing protection BKK al fine to preserve the plaster from damage caused by exposure to the elements without obstructing the porosity, a key property for the sound absorbing plaster Waterproofing the exposed join between the Diathonite Premix plaster and the concrete wall, using an elastic waterproofing liquid cement Acriflex Fybro reinforced to the join with an elastic band TNT Safety Joint. Necessary to prevent the occurrence of water infiltration which over time could lead to the detachment of the plaster from the concrete wall.

4 Anti reverberation, sound absorbing plaster Applying the solution Before intervening with the

pieces and anything that could compromise the adhesion of the sound absorbing plaster.

4 4 Anti reverberation, sound absorbing plaster Applying the solution Before intervening with the application if DiaSen products the wall was accurately cleaned by water jet to eliminate dust, loose pieces and anything that could compromise the adhesion of the sound absorbing plaster. First Phase The application of the adhesion agent Aquabond onto the concrete wall by use of an air-less in the ration of 0,400 Kg/m². This is necessary in order to guarantee the correct anchorage of the first layer of plaster onto a smooth surface with like the one in concrete upon which we were working. Application of Aquabond

Anti reverberation, sound absorbing plaster 5 Second Phase Application of the sound absorbing plaster Diathonite Premix by use of a traditional pump for premixed plaster.

application of the second layer of Diathonite premix until a thickness of 2cm is reached.

Once the pre- agreed thickness is reached the plaster is smoothed off and sanded down to prepare the surface for the Impregnating, waterproofing layer BKK.

5 Anti reverberation, sound absorbing plaster 5 Second Phase Application of the sound absorbing plaster Diathonite Premix by use of a traditional pump for premixed plaster. The first layer applied as a rough cast and therefore not more than 2 cm thick. 1. application of the first layer of Diathonite Premix 2. application of the second layer of Diathonite premix until a thickness of 2cm is reached. 1 2 The next day it is possible to proceed with the application of the successive layers increasing the load until a thickness of 5 cm is reached. Once the pre- agreed thickness is reached the plaster is smoothed off and sanded down to prepare the surface for the Impregnating, waterproofing layer BKK. In order to maintain a high level of sound absorbing any film like finishes are deliberately avoided and impregnation treatments used that won t in any way compromise the macro porosity and the maze of micro hollows that characterize the structure of Diathonite and that allow it to reach a value of a = 0.70; That is at the moment that the sound wave hits the surface the plaster is able to absorb and disperse 70% and only the remaining 30 % is reflected.

6 Anti reverberation, sound absorbing plaster Third Phase Therefore, once the plaster has

impregnating and waterproofing BKK using an air-less at a ratio of 0,35 Lt/m².

the exposure of Diathonite Premix to the elements.

the waterproofing of the joins between the plaster and the concrete wall, in order to avoid

In this case due to the length and narrowness on the surface to be treated it was opted to

using a roller, over the elastic band joint cover Safety Joint Roll, this is indispensable to

6 6 Anti reverberation, sound absorbing plaster Third Phase Therefore, once the plaster has matured and hardened, it is then possible to continue with the application of the impregnating and waterproofing BKK using an air-less at a ratio of 0,35 Lt/m². This operation, makes the surface water repellent and averts any potential problems caused by the exposure of Diathonite Premix to the elements. Application of waterproofing BKK Fourth phase At the end the intervention was completed with the waterproofing of the joins between the plaster and the concrete wall, in order to avoid any possible water infiltration into the fragile areas. In this case due to the length and narrowness on the surface to be treated it was opted to use the fiber-reinforced liquid waterproofer Acriflex Fybro- The application was carried out using a roller, over the elastic band joint cover Safety Joint Roll, this is indispensable to give the waterproofing the ability to follow the movement of a join between two different materials (concrete and Diathonite Premix) with two different dilation coefficients Application Fybro and Safety Joint

Anti reverberation, sound absorbing plaster 7 Certifications The levels LAeq, TM and L10 were determined by the highest noise

level of sound pressure decreases with increased distance, the reflected sound was less than the direct sound in every case.

vehicle when it is further away from the microphone, in these conditions the distance travelled by the direct sound waves and the

actually examining the differences of the L90 levels this amounted to 3,7dB The following graph shows the frequency spectrum of

Verification of sound absorbing at work on the concrete wall Verification of sound absorbing on the concrete wall covered in

7 Anti reverberation, sound absorbing plaster 7 Certifications The levels LAeq, TM and L10 were determined by the highest noise levels that impacted on the microphone, that is when the vehicle is positioned closer to the microphone, meaning they were determined by the direct sound field. Since the distance travelled by reflected sound waves is very much higher than that travelled by direct sound waves and since the level of sound pressure decreases with increased distance, the reflected sound was less than the direct sound in every case. More interesting however was the examination of the statistics L90 in that these parameters are determined by the noise of the vehicle when it is further away from the microphone, in these conditions the distance travelled by the direct sound waves and the reflected sound waves are the same and in this situation the effect of the sound absorbing coating is more significant and actually examining the differences of the L90 levels this amounted to 3,7dB The following graph shows the frequency spectrum of the minimum levels recorded in location P1 and P2. Verification of sound absorbing at work on the concrete wall Verification of sound absorbing on the concrete wall covered in Diathonite Premix From the above graph it is clear that the spectrum of minimum values in the level of sound pressure in the section with the sound absorbing plaster resulted much lower than the spectrum relative to the section with out the plastering. and furthermore the effectiveness of the treatment was significant even at low frequencies.

8 8 Anti reverberation, sound absorbing plaster Based on the observations described above it can be seen that the treatment of the smooth surface of the concrete wall with Diathonite has brought about a reduction in the intensity of the reflected sound waves compared to the non treated wall, with particular reference to the relevant minimum values which are more significant for the type of tests carried out, of 3,7dB. MEASUREMENT RESULTS Parameters to measure LAeqINT[dBA] LAeqì[dBA] Measurement Code P1 P2 Start date 30/09/09 30/09/09 Start time Duration Note with plaster without plaster LAeq,TM [dba] L10 [dba] L90 [dba] Limax [dba] - - Lfmax [dba] Lsmax [dba] - - KI [dba] 0 0 KT [dba] 0 0 KB [dba] 0 0 LAeq,TMC [dba] 0 0 LaeqTR [dba] LAeqTRC [dba] Daily weather conditions Parameters Period daytime nightime Sky Condition Sereno - Temperature ( C) - - Humididty (%) - - Wind Speed (m/s) <0.5 - Wind Direction - - Note: During the observation period the weather conditions were with in the boundaries set for the validity of measuring sound.w

9 9 Note

10 10 Note

11 11 Note

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DIATHONITE SCREED Thermal, breathable and lightened screed THERMAL ACOUSTIC INSULATION screed DIATHONITE SCREED 1731410 Fiber reinforced screed with cork (granulometry 03 mm 00.12 in), clay, diatomaceous powders and hydraulic binder. Natural readytouse compound