Sound insulation of a hollow concrete blocks wall made with construction and demolition waste and wood-based panels as linings

Abstract

It is a well-discussed topic that Construction and Demolition Waste (CDW) can be recycled and used as aggregate in the construction sector. Generally, Brazilian construction techniques are based on hollow blocks or bricks and mortars as coating systems. This paper describes the sound insulation of a masonry wall built with hollow concrete blocks and CDW as aggregates. The measurements were performed according to the reverberant chamber method. Keeping sustainability in mind instead of applying cement mortar as coating system, Oriented Strand Boards (OSB) and Wood-Wool Cement Boards (WWCB) were used and also tested as acoustical linings. The panels were directly attached on the wall with nails in the receiving room. All types of panels increased the weighted sound reduction index ( $R_{W}$ ). Wood-based composites can also improve the air quality because of their hygroscopic properties. In summary, sustainable wall systems were characterized according to their sound insulation properties, presented as possible substitutes for traditional masonry walls.

Keywords

Wood-based composites sound insulation construction and demolition waste hollow concrete blocks sustainable materials

Introduction

The use of masonry is spread all over Brazil and it is displayed by the assorted types, shapes, and materials. In Brazilian construction sector, both loadbearing and nonloadbearing walls are used, in which the walls are usually single leaf. Nowadays masonry is well consolidated in Brazil, fulfilling an important part of the construction market.¹

The waste of the masonry system is classified by the National Environmental Council² as being reusable or recyclable for use as aggregates for construction activity. The recycling of these materials is not a pervasive practice in Brazil.³

Construction and demolition waste (CDW) is a multinational problem. The estimated CDW production in Brazil is around $500 k g$ /year per capita, which is variable and correlated with the human development index (HDI), from one region to another. CDW represents the largest amount of municipal solid waste.⁴ Disposing of CDW through landfill increases the depletion of land resources and illegally disposal of waste pollutes soil, water, and air. How to solve the existent garbage siege phenomenon and minimize CDW is an urgent and challenging issue around the world.⁵

Neto and Correia⁶ noticed the economic and environmental advantages of implementing reverse logistics to recycle solid waste from construction companies in Brazil. The authors interviewed two construction companies which profited with CDW recycling strategies. Furthermore, the environmental impact was reduced.

Lime-cement mortar is widely used as masonry coating system in Brazil. Condeixa et al.³ described in their research the lime as the material component with the largest contribution in the Life Cycle Impact Analysis, whereas the use phase is the phase with the highest associated impact.

About the influence of the building materials on the acoustic performance, good sound insulation requires an airtight partition wall. In masonries built with porous concrete or some types of brick walls, this means that the surface must be treated with plaster, preferably on both sides.⁷

The sound reduction index depends on the bending stiffness of the structure and on the energy losses of vibrations⁸ through three different contributions: internal losses, boundary losses, and radiation losses.⁷

For a typical Brazilian masonry wall (built with ceramic blocks and lime-cement mortar) Friedrich et al.⁹ measured an improvement over the sound reduction index ( $R_{W}$ ) about 5 dB with the addition of mortar on both sides of the wall. But not only mortars can be used as a sealing system of porous walls. The addition of linings contributes to the increase of the sound insulation in the mid- and high-frequency ranges while reducing it near the massspringmass resonance.¹⁰ Sometimes, the partition wall should provide sound absorption in the rooms. Treating a surface with a sound absorbing material may influence the sound transmission.⁷

Uris et al.¹¹ related that when a perforated absorptive facing is added to a single frame partition, the sound insulation improvements might occur in the mid and high frequency. The authors studied the effect of perforated gypsum boards mounted in a steel frame with an air cavity of $100 m m$ on a bare wall built with common drywall.

Acoustic comfort is not an exclusive goal when designing a wall system. There are other factors that define the indoor environmental quality as thermal comfort, indoor air quality, and visual comfort.¹² In terms of air quality, the indoor humidity has a significant effect on occupant comfort, perceived air quality (PAQ), occupant health, material emissions, building durability, and energy consumption.¹³

Simonson et al.¹³ reported an improvement on the PAQ by applying hygroscopic wood-based materials in a test-bedroom at different European climates. Osanyintola and Simonson¹⁴ described the energy impact over an environment with the inclusion of wood-based materials because of their hygroscopic properties. The authors mentioned that the potential direct energy savings are small for heating ( $23 %$ of the total heating energy), but significant for cooling ( $530 %$ of the total cooling energy).

For different commercial bio-based insulation materials, Palumbo et al.¹⁵ measured the Moisture Buffering Value (MBV), which indicates the quantity of water that is transported in or out of a material per open surface area during a certain period, when the material is exposed to variations in relative humidity of the circumambient air.¹⁶ They noticed a good moisture buffering capacity of the analyzed materials, including a Wood-Wool Cement Board (WWCB), that is one of the two groups of materials evaluated in this research. Another on-topic material is the Oriented Strand Board (OSB). Vololonirina et al.¹⁷ confirmed its hygroscopic properties and suggested it as thermal regulator. Also, in a recent review, Kreiger and Srubar¹⁸ detailed the MBV of different building materials and concluded that biotic materials, as wood composites, have higher moisture buffering effect than abiotic materials, such as mortars and gypsum.

This research presents two types of wood-based lining systems for a hollow concrete blocks wall built with CDW. They were investigated as options to the common mortar coating system toward a sound reduction index improvement. The wood panels were nailed directly on the wall in an indoor environment.

Materials and methods

Construction and demolition waste (CDW) as aggregates in hollow concrete blocks

The recycled concrete blocks were built according to Brazilian standards concerning their use in a nonloadbearing wall and the appropriate composition of CDW for its application.¹⁹ Comparisons between different national standards for recycled aggregates applications are presented by Tam et al.²⁰

Fine and coarse aggregates, presented in Figures 1 and 2 respectively, were obtained from a recycling plant located in the south part of Brazil. Their properties are shown in Table 1.

Figure 1.

Fine aggregate.

Figure 2.

Coarse aggregate.

Table 1.

Properties of fine and coarse aggregate.

Parameter	Fine	Coarse
Fineness modulus	3.17	6.02
Maximum characteristic Dimension (mm)	4.75	12.5
Specific mass (g/cm3)	2.53	2.65
Water absorption (%)	16.0	10.0
Sulphates (%)	<1.00	<1.00
Chlorides (%)	<1.00	<1.00
Non-mineral materials (%)	<2.00	<2.00
Clay clods (%)	<2.00	<2.00
Total contaminant content (%)	<3.00	<3.00
Material passing through mesh sieve 75 μ5 (%)	<5.0	<10.0
Content of cement and rock fragments (%)	–	>90.0

The grading curve for fine aggregate is presented in Figure 3. The high portion of fine materials contained in sand granulometry implied in an elevated water absorption because of its larger contact area. For this reason, the Brazilian standard NBR 15116 (2004)¹⁹ recommends a pre-wetting of the fine material before its application (a value about $80.0 %$ of the aggregates water absorption). Comparing with other guidelines for concrete aggregates, the fine aggregate did not meet the specification of the North American standard ASTM C33 (2018)²¹ for sieve size of $2.36 m m$ , as shown in Table 2.

Figure 3.

Grading curve for fine aggregate.

Table 2.

Comparison with ASTM C33 recommendation for fine aggregates.

Sieve size (mm)	Percent passing	ASTM C33 limits
9.50	100.0	100.0
6.30	100.0	–
4.75	98.6	95.0 – 100.0
2.36	74.3	80.0 – 100.0
1.18	54.0	50.0 – 85.0
0.60	36.1	25.0 – 60.0
0.30	16.0	5.00 – 30.0
0.15	3.84	0.00 – 10.0

The coarse aggregate gradings curve is shown in Figure 4. Its nominal size was estimated to be within $4.75$ and $12.5 m m$ .

Figure 4.

Grading curve for coarse aggregate.

For the coarse aggregate, a large amount of fine materials was observed, outlining its granulometric curve outside the usable zone at the $6.30 m m$ sieve mesh size. For this reason, several adjustments over the concrete mix were made without compromising its performance.

Contrasting with ASTM C33²¹ for the described nominal size (corresponding to the size classification number 7), a disagreement occurred at the $9.50 m m$ sieve size, as shown in Table 3. The presence of a significant percentage of fine materials in the coarse aggregate composition is due to the adhesion of these particles on its surface, caused by the storage’s exposure to weathering and by the high concentration of cementitious material in the construction waste structure.

Table 3.

Comparison with ASTM C33 recommendation for coarse aggregates.

Sieve size (mm)	Percent passing	ASTM C33 limits
25.0	100.0	–
19.0	100.0	100.0
12.5	100.0	90.0 – 100.0
9.50	94.16	40.0 – 70.0
4.75	0.58	0.00 – 15.0
2.36	0.58	0.00 – 5.00

Friction during concrete mixing separates the fine particles from the coarse aggregate surface, creating more fine materials in the concrete formation. That phenomenon led to an additional attention when preparing the concrete, because reducing the coarse portion would also reduce the resistance and increase the water absorption.

A high early strength cement type V (HESC—type V) was chosen, according to the Brazilian standard NBR 16697.²² which is comparable to type III described by ASTM C150/C150M.²³ According to Hanif et al.,²⁴ recycled coarse aggregate significantly reduces the concrete strength, which can be compensated by the use of HESC instead of ordinary cement.

Different specimens with $10.0 c m$ diameter and $20.0 c m$ height were prepared with a variety of concrete recipes, as guided by the standard NBR 5739,²⁵ which has the corresponding ASTM standard C39/C39M.²⁶

The proportion that provided the best strength performance was $1 : 3.5 : 1.5 : 0.63$ , corresponding to volume quantities of cement, fine aggregate, coarse aggregate, and water, respectively. The hollow blocks were then built with that recipe and all the national guidelines²⁷ for hollow concrete blocks as part of masonry walls were followed. Their average water absorption and weight were equal to $14.49 %$ and $11.85 K g$ , per unit respectively. Figure 5 describes the cross-section of the block.

Figure 5.

Cross-section of the hollow concrete block.

The Brazilian standard allows the use of blocks with $f_{b k} \geq 3.00 M P a$ and water absorption below $11.0 %$ (for normal-weight aggregates) as buildings elements of nonloadbearing walls and the results concerning their mechanical properties are presented in a later section. Even though the water absorption was greater than standard recommendation, the blocks were not discarded. Eckert and Oliveira²⁸ described how to attenuate that effect aiming the concrete quality. The authors concluded that a pre-wetting of the recycled aggregate could mitigate the negative effects of excessive water absorption, and that procedure was taken into account when developing the blocks.

The CDW hollow blocks wall built as a sample in a reverberation chamber is shown in Figure 6.

Figure 6.

Concrete masonry with hollow blocks in a reverberation chamber.

Figure 7 illustrate a generic section of the wall with mortar joints size. Considering that wall system, the mass per unit area ( $m'$ ) is $160.28 K g / m^{2}$ .

Figure 7.

Concrete masonry with hollow blocks in a reverberation chamber.

Wood-based panels as lining system

With the intention to improve the sound insulation of the CDW hollow blocks wall, two different types of wood-based panels were chosen as lining systems for an interior environment: Oriented Strand Boards (OSB) and Wood-Wool Cement Boards (WWCB). The application of these material are not new in the building sector, but there is a lack of data concerning their sound insulation properties when used as lining system. Their surfaces are presented by Figure 8.

Figure 8.

(a) WWCB with superfine straws (SFS), (b) WWCB with thick straws (TKS), and (c) OSB.

Their densities were measured according to the European Standard EN 323²⁹ consisting of ten samples of each material measuring $50.0 \times 50.0 m m$ . The samples stayed in an appropriate stove for 48 h within a controlled environment (relative humidity about $65 \pm 5 %$ and temperature about $20 \pm 3^{\circ} C$ ). After the first 24 h their mass were measured, and after 48 h it was checked that the mass did not vary more than $0.1 %$ from the 24-h measurement.

All groups resulted in normal distributions, and a $95 %$ confidence interval (CI) was calculated for each kind of composite with a t test. The measurements that did not settle between the CI values were excluded and a new average was calculated with those established within the CI. The analysis were performed in the R software.³⁰

At most, Brazilian OSB are manufactured with pine wood particles obtained from dedicated forests mainly from Pinus elliottii and Pinus taeda (loblolly pine).³¹ These species are not native and reforestation programs provide them.

Three different thicknesses of OSB were tested: $8.00$ , $12.0$ , and $25.0 m m$ . The panels were nailed on the wall, as discussed in the next section.

The Wood-Wool Cement Boards manufactured in Brazil are typically made from the same wood species as OSB, described previously. It is still not widespread in Brazil, since its application is more centered on the composition of partition walls and ceilings, aiming to provide acoustic insulation in indoor environments.³² Botterman et al.³³ described the WWCB as a potential sound absorber and also noticed that the material composition can be modeled in order to provide an optimal sound absorption coefficient.

The influence of three different thicknesses of WWCB ( $17.0$ , $25.0$ , and $50.0 m m$ ) over the masonry sound insulation was evaluated based on a thick-straw type of composite (TKS—straws width $\geq 3.00 m m$ ). The performance of a $25.0 m m$ thick superfine-straw composite (SFS—straws width ) was also evaluated.

Acoustic measurements

The sound reduction indexes were measured for the different samples in a reverberation chamber built according to the ISO 10140.^34
–37 The chamber’s dimensions are shown in Figures 9 and 10. The distances between microphones (indicated by letter “M”) and sound-sources (indicated by letter “S”) are also presented. The volume of the emission room is about $57.02 m^{3}$ , and the receiving room has a volume about $51.84 m^{3}$ . $″ 1.00 m m$

Figure 9.

Overview of the chamber’s floor plan.

Figure 10.

AB section of the reverberation chamber.

Firstly, the airborne sound insulation of the wall without any additional panel was measured, as presented by Figure 11.

Figure 11.

Hollow concrete blocks as masonry wall.

After that, the panels were attached by nails ( $\emptyset 3.5 m m \times 82.8 m m$ ) as displayed by Figure 12. Figures 13 and 14 present the fixation schemes for the OSB and WWCB, respectively.

Figure 12.

Generic section of a panel fixation.

Figure 13.

Fixation scheme for OSB.

Figure 14.

Fixation scheme for WWCB.

Finally, the samples were mounted for the acoustic measurement, as illustrated by Figures 15 and 16.

Figure 15.

Masonry wall with OSB as lining.

Figure 16.

Masonry wall with WWCB as lining.

The sound pressure level measurements in the source and receiving room were performed with a Bruel&Kjær Type 2250-Light analyzer. The reverberation time in the receiving room was calculated from an impulse response measured with a $1 / 2$ inch random incidence microphone (type 46AQ—GRAS) plugged in a CCP power supply (type 12AL GRAS) and then in a USB sound card (AudioBox USB 96—PreSonus). An omnidirectional sound source model (type DDC-100—GROM) delivering a maximum sound power of $109 d B$ re $1 p W$ ( $100$ $3150 H z$ ) was utilized. The impulse response was obtained through the deconvolution technique with a logarithmical sine-sweep as excitation signal. The ITA-Toolbox on Matlab software was used for the impulse response acquisition and reverberation time calculation.

All the guidelines of the international standards^34
–37 concerning the calculated parameters, background noise correction, microphone and loudspeaker positions were followed.

Prediction of the sound reduction indexes

Considering an orthotropic behavior

The prediction of sound insulation can be reached using the equations related by Granzotto et al.³⁸ with some complementary information given by the literature for an orthotropic plate. Initially vertical and horizontal compressive strength of the blocks were measured, described as $f_{b k}$ and $f_{' b k}$ respectively. The compressive strength for the laying mortar is indicated as $f_{m}$ . The applied mortar was similar to the type III mortar described in the research of Castro et al.³⁹

The vertical compressive strength of the wall ( $f_{k}$ ) is given by equation (1):⁴⁰

f_{k} = K . {f_{b k}}^{0.7} . {f_{m}}^{0.3}

(1)

The equation (2) describes the horizontal compressive strength of the wall (fhk).

f_{h k} = K . {f_{' b k}}^{0.7} . {f_{m}}^{0.3}

(2)

According to the Eurocode 6⁴⁰ the hollow block in-test can be classified in Group 3, leading to $K = 0.40$ .

Vertical ( $E_{v}$ ) and horizontal ( $E_{h}$ ) Modulus of Elasticity of the wall are giv $f_{h k}$ en by equations (3) and (4).³⁹

E_{v} = 1180 . {f_{k}}^{0.83}

(3)

E_{h} = 1180 . {f_{h k}}^{0.83}

(4)

Table 4 summarizes the mechanical properties of the building elements.

Table 4.

Mechanical properties of elements.

fbk(MPa)	f'bk(MPa)	fm(MPa)	fk(MPa)	fhk(MPa)	Ev(MPa)	Eh(MPa)
3.05	0.60	4.50	1.37	0.44	1533	596

The equable modulus of elasticity can be written as function of the in-plane ( $φ$ ) angle by the equation (5):^38,41,42

E_{φ} = (\sqrt{E_{h}^{*}} \cos^{2} φ + \sqrt{E^{*}} \sin^{2} φ)

(5)

Where the elasticity moduli can be noted in their complex form as indicated by equations (6) and (7):³⁸

E^{*} = E (1 + i η)

(6)

E_{h}^{*} = E (1 + i η)

(7)

The total loss factor ( $η$ ) can be estimated according the equation (8) for a laboratory condition:⁴³

η = η_{i n t} + \frac{m'}{485 \sqrt{f}}

(8)

Where $m^{'}$ is the mass per unit area of the wall, $f$ is the center frequency within the one-third octave band interval and $η_{i n t}$ is the internal loss factor, set as $0.01$ for concrete.⁷ The shear modulus ( $G_{φ}$ ) and the bending stiffness ( $B_{φ}$ ) functions can be written according the equations (9) and (10):³⁸

G_{φ} = \frac{E_{φ}}{2 (1 + ν)}

(9)

B_{φ} = \frac{E_{φ} h^{3}}{12 (1 - ν^{2})}

(10)

Where $h$ is the thickness of the wall and $ν$ is the Poisson ratio, assumed as $0.20$ as indicated by Rindel⁷ for concrete.

For non-isotropic panels the wall’s impedance depends on the angle of incidence ( $θ$ ) an on the in-plane angle ( $φ$ ). Due that, the normalized impedance ( $z_{T}$ ) can be computed according the equation (11).³⁸

z_{T} = \frac{1}{Z_{0}} \frac{{[ρ h + (\frac{ρ h^{3}}{12} + \frac{ρ B_{φ}}{G_{φ}}) \frac{ω^{2}}{c_{0}^{2}} \sin^{2} θ] ω - [\frac{B_{φ}}{c_{0}^{4}} \sin^{4} θ + \frac{ρ h^{3}}{12 G_{φ}} ω^{3}]}}{[1 + \frac{B_{φ} ω^{2} \sin^{2} θ}{G_{φ} c_{0}^{4} h} - \frac{ρ h^{2} ω^{2}}{12 G_{φ}}]} i

(11)

Where $Z_{0}$ is the impedance of the air, about $412 N s / m^{3}$ ;⁴⁴ $ρ$ is the density of the wall ( $1144.87 K g / m^{3}$ ); $c_{0}$ is the speed of sound in air; $ω$ is the angular frequency ( $ω = 2 π f$ ;) and $i$ is the imaginary unit.

For an infinite isotropic plate having mass and stiffness the angle-dependent transmission coefficient ( $τ_{θ}$ ) can be described by the equation (12).³⁸

τ_{θ} = 4 {| \frac{1}{2 + z_{T} \cos θ} |}^{2}

(12)

Combining the equations (11) and (12) a transmission coefficient that comprehends $θ$ and $φ$ angles is obtained, described as .³⁸ For an orthotropic material and considering a diffuse field, the sound transmission coefficient ( $τ_{d}$ ) can be calculated by the equation (13).⁴⁵

τ_{d} = \frac{1}{π} \int_{0}^{2 π} \int_{0}^{\frac{π}{2}} τ_{θ, φ} \cos (θ) s i n (θ) d θ d φ

(13)

The sound reduction index is given by the equation (14).

R = - 10 \log_{10} (τ_{d})

(14)

Considering the mass law

The mass law expresses the airborne sound insulation of a plate as function of its mass per unit area. The mass law assumes that all parts of a plate move in phase and also that the bending stiffness can be disregarded. It is applicable to large homogeneous and uniform plates and it presumes an excitation by a plane sound wave at normal incidence. The equation (15) describes the sound reduction index ( $R_{0}$ ) as function of the angular frequency ( $ω$ ), the density of the air ( $ρ_{0}$ ), the sound speed in the air ( $c_{0}$ ), and the mass per unit area of the material ( $m$ ).⁷

R_{0} = 10 \log_{10} [1 + {(\frac{ω m}{2 ρ_{0} c_{0}})}^{2}]

(15)

Prediction of the critical frequencies

Masonry wall without lining system:

The important difference between an isotropic and an orthotropic plate is that latter has two different critical frequencies corresponding to the different bending stiffness (i.e. at $x$ and $y$ axis).⁷ They are shown by equations (16) and (17).

f_{c x} = \frac{c_{0}^{2}}{2 π} \sqrt{\frac{m}{B_{x}}}

(16)

f_{c y} = \frac{c_{0}^{2}}{2 π} \sqrt{\frac{m}{B_{y}}}

(17)

Where $B_{x}$ and $B_{y}$ are the bending stiffness on the $x$ and $y$ axis respectively, calculated as the product of the moment of inertia by the modulus of elasticity of each axis. The calculation considered a system composed by a block unit (Figure 5) as a rigid body. It was expected a coincidence frequency between $f_{c x}$ and $f_{c y}$ .

Results and discussion

Bulk density

The values obtained after the statistical treatment are displayed in Table 5. An analysis with ANOVA and a post-hoc Tukey test showed that the $25.0 m m$ thick OSB samples were statistically different from $8.00$ and $12.0 m m$ thick samples in terms of density, although the $8.00$ and $12.0 m m$ thick were statistically similar.

Table 5.

Bulk densities of the wood-based composites.

Composite	Bulk density (g/cm3)
8.00 mm thick OSB	0.61
12.0 mm thick OSB	0.61
25.0 mm thick OSB	0.51
17.0 mm thick WWCB (TKS)	0.47
25.0 mm thick WWCB (TKS)	0.41
25.0 mm thick WWCB (SFS)	0.68
50.0 mm thick WWCB (TKS)	0.36

Using the same analysis for the WWCB type with thick straws (TKS), one observes that the densities of the $17.0 m m$ thick samples are statistically different from $25.0$ and $50.0 m m$ thick samples densities. However, $25.0$ and $50.0 m m$ thick samples densities are similar, which means that their composition could be the same.

All the composites were manufactured in industrial plants, with quality control and well-organized procedures. The results showed that the assumption that they have the same densities within their group cannot be made.

Sound reduction indexes

The weighted sound reduction index ( $R_{W}$ ) for the masonry wall with and without panels attached is shown in Table 6 according to ISO 717-1 (2013)⁴⁶ procedures. Spectrum corrections $C$ and $C_{t r}$ are also presented.

Table 6.

Measured weighted sound reduction indexes.

Sample	Rw(dB)	C(dB)	Ctr(dB)
CDW hollow blocks masonry wall	30	–1	–3
8.00 mm thick OSB	33	–1	–4
12.0 mm thick OSB	34	–1	–4
25.0 mm thick OSB	31	–1	–3
17.0 mm thick WWCB (TKS)	32	–1	–3
25.0 mm thick WWCB (TKS)	32	–1	–4
25.0 mm thick WWCB (SFS)	32	–1	–3
50.0 mm thick WWCB (TKS)	33	–1	–5

For different thicknesses of OSB nailed on the CDW hollow blocks wall, the sound insulation measurements are described in Figure 17. Figure 18 shows the sound insulation measurements for WWCB nailed on the wall. In both of the schemes the sound reduction index prediction are presented, considering the hollow blocks wall without additional layers.

Figure 17.

Sound insulation improvement with OSB.

Figure 18.

Sound insulation improvement with WWCB.

From $100$ to $125 H z$ there is an improvement on transmission loss in a region controlled by the stiffness, and a drop happened at a $160 H z$ resonant frequency, probably caused by the air cavity of the blocks.⁷ At higher frequencies there is a second dip at $1250 H z$ for the masonry with and without linings. The calculated critical frequencies $f c x$ and $f c y$ were $711$ and $1263 H z$ , respectively, which indicates that second coincident dip occurred within the critical frequency interval as expected. This dip evinced a coincident frequency effect associated with the thin surface layer of the hollow blocks and lining systems, as described by Fringuellino and Smith.⁴⁷

For the hollow brick wall without lining, the straight horizontal tendency in the high-frequency range (above $1000 H z$ ) occurs due two different mechanisms related to the thickness of the wall, which are the shear waves and thickness resonance. In thin walls, the bending wave speed increases with frequency, what does not happen by the same way with thick walls. There is limit that shear deformation and rotational inertia give to group and phase wave speeds, which is a common value at high frequencies, resulting in a plateau effect. The same effect was noticed by Fringuellino and Smith⁴⁷ and Grazotto et al.³⁸

The OSB minimized the plateau effect above $1250 H z$ . The addition of the WWCB did not change the shape of the wall insulation curve, keeping the plateau effect.

Higher sound insulation was measured with the OSB nailed on the hollow blocks wall. Above $1250 H z$ the slope changed from $5$ to $8 d B$ /octave due to the increase of the walls bending stiffness and losses provided by the OSB lining systems. Similar contributions were achieved by Scamoni et al.⁸ with an innovative coating system for a masonry wall, differing on levels, and position of the coincident valley.

A resonance reaction may be observed in all the samples with WWCB and with the $12.0 m m$ thick OSB at the $100 H z$ frequency. The same effect was reported by Warnock⁴⁸ who described the influence of a cavity between a layer of drywall attached to masonry. According to the research, gluing or screwing a drywall direct to a masonry wall would create a mass-spring-mass resonance at the low-frequency range, decreasing the transmission loss. It happened due the fact that an air gap, even of small one, still existed between layers, which allowed a fairly vibration of the gypsum layer, featuring the mass-spring-mass system.

The low sound insulation performance at the low-frequency range is also related to the orthotropic behavior of the hollow brick wall, corresponding to the coincidence zone, as described by Granzotto et al.³⁸

The mass law can not be applied in order to predict the sound insulation for a wall built with the tested blocks. As shown by Figures 17 and 18 it overestimated the sound reduction indexes. On the other hand, the orthotropic model approached to the measured values for frequencies between $500$ and $1000 H z$ , despite the fact that it did not converge to the measured values for the low and high frequency range.

According to standard ISO 12354-1,⁴³ the improvement over the weighted sound reduction index by adding layers directly on a base element depends on the mass unit per area of the elements (basic structural material and additional layer) and on the dynamic stiffness of the additional layer. With these parameters, a resonance frequency ( $f_{0}$ ) for the combined elements can be determined. Resonance frequencies below $200 H z$ improve the $R_{W}$ value. Above that, $R_{W}$ values are degraded. In line with ISO 12354-1⁴³ statements, it can be assumed that the resonance frequencies for all tested samples are within $160$ and $200 H z$ because all of them improved the wall’s weighted sound reduction index in at least $1 d B$ .

Conclusion

This paper investigated the use of wood-based composites as lining systems of a hollow concrete blocks masonry built with Construction and Demolition Waste as concrete aggregates. Some materials such as Oriented Strand Boards (OSB) and Wood-Wool Cement Boards (WWCB) were added on the wall and the experiments showed that the addition of Wood-Wool Cement Boards did not improve the sound insulation of the hollow blocks wall ( $R_{W} = 30 d B$ ) as much as the inclusion of the Oriented Strand Boards. The measured DRw values for WWCB as additional layers were within $1$ and $3 d B$ and reached $4 d B$ with the inclusion of the OSB with $25.0$ and $12.0 m m$ thicknesses.

Regarding the prediction models, it was verified that neither the applied methods were accurate. For the orthotropic model this might be due to the type of the air cavities, which are not well distributed as the ones observed in the research that implemented a similar prediction model ³⁸ and reached acceptable results. A specific analytical model for that type of wall should be implemented.

The results corroborates that WWCB can be used as a lining system if the reverberation time control in an indoor environment is a goal due to their absorption properties. If only sound insulation is the issue, the results indicate the use of OSB instead of WWCB.

All analyzed types of wood-based panels as lining systems increased the weighted sound reduction index.

A more sustainable masonry wall compared with traditional masonries was presented. In future research it is intended to perform a thermal analysis of the proposed masonry system complementing its characterization.

Footnotes

Acknowledgements

The authors would like to thank the researches at the Institute of Technical Acoustics of the RWTH Aachen University for the development and distribution of the ITA-Toolbox.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was financed in part by the Coordenao de Aperfeioamento de Pessoal de Nvel Superior—Brasil (CAPES) —Finance Code 001 and Conselho Nacional de Desenvolvimento Cientfico e Tecnolgico—Brasil (CNPq).

ORCID iDs

Rodrigo Scoczynski Ribeiro

Rosemara Santos Deniz Amarilla

Luis Henrique Sant’Ana

References

Correa

The evolution of the design and construction of Masonry Buildings in Brazil. Gestão e Tecnologia de Projetos 2012; 7(2): 3–11.

CONAMA. Resolution n. 307, 2002. http://www.mma.gov.br/port/conama/legiabre.cfm?codlegi=338 (accessed 4 February 2021).

Condeixa

Haddad

Boer

Life cycle impact assessment of masonry system as inner walls: a case study in Brazil. Constr Build Mater 2014; 70: 141147.

Contreras

Teixiera

Lucas

, et al. Recycling of construction and demolition waste for producing new construction material (Brazil case-study). Constr Build Mater 2016; 123: 594600.

Hao

Yuan

Liu

, et al. A model for assessing the economic performance of construction waste reduction. J Clean Prod 2019; 232: 427–440.

Neto

GCO

Correia

JMF

. Environmental and economic advantages of adopting reverse logistics for recycling construction and demolition waste: a case study of brazilian construction and recycling companies. Waste Manage Res 2019; 37(2): 176–185.

Rindel

JH.

Sound insulation in buildings. 1st ed. Boca Raton: CRC Press, 2018. ISBN 9781498700429.

Scamoni

Piana

Scrosati

Experimental evaluation of the sound absorption and insulation of an innovative coating through different testing methods. Build Acoust 2017; 24(3): 173–191.

Friedrich

da Paixao

Vergara

. Contribution of wall coating to the acoustic performance of masonry walls. INTER-NOISE NOISE-CON Congr Conf Proc 2010; 2010(5): 5772–5779.

10.

Hopkins

Sound insulation. 1st ed. Oxford: Butterworth-Heinemann, 2007. ISBN 978-0-7506-6526-1.

11.

Uris

Plana-sala

JMB

Estellés

Experimental sound insulation performance of single frame partitions with the addition of a sound-absorptive perforated board. Acta Acust United Acust 2008; 94(2): 321–325.

12.

Sarbu

Sebarchievici

Aspects of indoor environmental quality assessment in buildings. Energy Build 2013; 60: 410419.

13.

Simonson

Salonvaara

Ojanen

The effect of structures on indoor humidity–possibility to improve comfort and perceived air quality. Indoor Air 2002; 12(4): 243–251.

14.

Osanyintola OF and Simonson CJ. Moisture buffering capacity of hygroscopic building materials: experimental facilities and energy impact. Energy Build 2006; 38(10): 12701282.

15.

Palumbo

Lacasta

Holcroft

, et al. Determination of hygrothermal parameters of experimental and commercial bio-based insulation materials. Constr Build Mater 2016; 124: 269275.

16.

Peuhkuri

Rode

Svennberg

, et al. Moisture buffering of building materials. Number R-126 in DTU BYG-rapporter, Denmark: Danmarks Tekniske Universitet, 2006. ISBN 87-7877-195-1.

17.

Vololonirina

Coutand

Perrin

Characterization of hygrothermal properties of wood-based products – impact of moisture content and temperature. Constr Build Mater 2014; 63: 223233.

18.

Kreiger

Srubar

WV.

Moisture buffering in buildings: a review of experimental and numerical methods. Energy Build 2019; 202: 109394.

19.

Brazilian National Standards Organization. NBR 15116 – recycled aggregate of solid residue of building construtions: requirements and methodologies, 2004.

20.

Tam

VWY

Soomro

Evangelista

ACJ.

A review of recycled aggregate in concrete applications (2000–2017). Constr Build Mater 2018; 172: 272292.

21.

ASTM C33/C33M-18. Standard specification for concrete aggregates. Technical Report, ASTM International, West Conshohocken, PA, 2018. DOI:10.1520/C0033_C0033M-18.

22.

Brazilian National Standards Organization. NBR 16697 – Portland cement: requirements, 2018.

23.

ASTM C150/C150M-20. Standard specification for Portland cement. Technical Report, ASTM International, West Conshohocken, PA, 2020. DOI:10.1520/C0150_C0150M-20.

24.

Hanif

Kim

Lee

, et al. Influence of cement and aggregate type on steam-cured concrete – an experimental study. Magaz Concr Res 2017; 69(13): 694702.

25.

Brazilian National Standards Organization. NBR 5739 – concrete: compression test of cylindrical specimens, 2018.

26.

ASTM C39/C39M-20. Standard test method for compressive strength of cylindrical concrete specimens. Technical report, ASTM International, West Conshohocken, PA, 2020. DOI:10.1520/C0039_C0039M-20.

27.

Brazilian National Standards Organization. NBR 6136 – hollow concrete blocks for concrete masonry: requirements, 2016.

28.

Eckert

Oliveira

Mitigation of the negative effects of recycled aggregate water absorption in concrete technology. Constr Build Mater 2017; 133: 416424.

29.

European Committee for Standardization. EN 323 – wood-based panels. Determination of density, 1993.

30.

RCoreTeam. R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria, 2019. https://www.R-project.org/ (accessed 4 February 2021).

31.

Ferro

Silva

DAL

Lahr

FAR

, et al. Environmental aspects of oriented strand boards production. A Brazilian case study. J Clean Prod 2018; 183: 710719.

32.

Nogueira

JRS

Callejas

IJA

Durante

LC.

Desempenho de painel de vedação vertical externa em Light Steel Framing composto por placas de madeira mineralizada. Ambiente Construido 2018; 18: 289307.

33.

Botterman

Doudart de la Grée

GCH

Hornikx

MCH

, et al. Modelling and optimization of the sound absorption of wood–wool cement boards. Appl Acoust 2018; 129: 144–154.

34.

ISO 10140-2. Acoustics – laboratory measurement of sound insulation of building elements – part 2: measurement of airborne sound insulation, 2010.

35.

ISO 10140-4. Acoustics – laboratory measurement of sound insulation of building elements – part 4: measurement procedures and requirements, 2010.

36.

ISO 10140-5. Acoustics – laboratory measurement of sound insulation of building elements – part 5: requirements for test facilities and equipment, 2010.

37.

ISO 10140-1. Acoustics – laboratory measurement of sound insulation of building elements – part 1: application rules for specific products, 2016.

38.

Granzotto

Di Bella

Piana

EA.

Prediction of the sound reduction index of clay hollow brick walls. Build Acoust 2020; 27(2): 155–168.

39.

Castro

Alvarenga

RCSS

Silva

, et al. Experimental evaluation of the interaction between strength concrete block walls under vertical loads. Revista IBRACON de Estruturas e Materiais 2016; 9: 643–681.

40.

European Committee for Standardization. Eurocode 6 design of masonry structures. Part 1-1: general rules for reinforced and unreinforced masonry structures. Technical Report, 2005.

41.

Santoni

Bonfiglio

Fausti

, et al. Vibro-acoustic optimisation of wood plastic composite systems. Constr Build Mater 2018; 174: 730–740.

42.

Nilsson

Liu

Vibro-acoustics, vol 1. Science Press, 2015. ISBN 978-3-662-47807-3.

43.

ISO 12354-1. Building acoustics – estimation of acoustic performance of buildings from the performance of elements – Part 1: airborne sound insulation between rooms, 2017.

44.

Long

Architectural acoustics. 2nd ed. Elsevier Academy Press, 2014.

45.

Wareing

Davy

Pearse

JR.

The sound insulation of single leaf finite size rectangular plywood panels with orthotropic frequency dependent bending stiffness. J Acoust Soc Am 2016; 139(1): 520–528.

46.

ISO 717-1. Acoustics – rating of sound insulation in buildings and of building elements – Part 1: airborne sound insulation, 2013.

47.

Fringuellino

Smith

RS.

Sound transmission through hollow brick walls. Build Acoust 1999; 6(3): 211–224.

48.

Warnock

ACC

. Sound transmission through concrete blocks with attached drywall. J Acoust Soc Am 1991; 90(3): 1454–1463.