Impact sound transmission tests on a concrete slab floor with various surface constructions

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Impact sound transmission tests on a concrete slab floor with various

surface constructions

IMPACT SOUND TTUNSMISSION TESTS

ON

A CONCRETE

SLkB

SURFACE CONSTRUCTIONS C A N A D A 21 -, , LJ3$3 5-,*

I

.

I

. .

I

i

IMPACT SOUND TRANSP\/IISSION TESTS ON A CONCRETE SLAB

FLOOR

In a recent pager (11, two methods for evaluating the resistance of

a f l o o r to h p a c t sounds such as footsteps were compared. The fir st

method i s the w e l l - h o w n ISOfFHA procedure for determining impact trahsmission through f l o o x s : the _procedure is to compare the spectra of transmitked noise produced by a standard tapping machine adopted f o r t h i s

purpose by Technical. Conunittee 4 3 of the international Standards Organ-

ization ( 2)

.

r

s cherne;

The current procedure for rating t h e impact sound insulation of

a

floor is a two-step process. First, the s p e c t r u m of noise transmitted through a floor from a standard tapping machine i s measured. Secondly,

the spectrum of transrnified machine noise i s compared with a standard arbitrary reference spectrum; thus, a single figure of merit for t h e impact

sound insulation of the f l o o r is determined. For a floor to have satisfactory impact sound insulation, the general consensus is t h a t its h p a c t Noise

Rating should be zero or positive.

The second method devised for these t e s t s involves a direct

subjective comparison of loudnesses of footsteps transmilked through f l o o r s , The purpose was to u s e this subjective evidence to a s s e s s the validity of the machine method. Briefly, the procedure for obtaining subjective loudness comparisons w a s to make magnetic tape recordings of footsteps

on two a o o r s . A jury of observers (six to ten) then listened alternately t o

the t w o sets of footstep sounds and adjusted the g a i n of one amplifier until

t h e two sounds w e r e judged equally loud. The d s e r e n c e in gain (in decibels] between the tvi.0 amplifier s thus provided a quantitative comparison of the

loudnesass of the two sounds, More details of the experimental procedure will be found in _{Reference 1.}

As the paper was concerned

mith

t e s t results for specific floora, the individual floor constructions w e r e n o t

described. F o r the benefit of ot&er workers in the field,

the

All measurements w e r e made en an 8 by 8 ft by 4 in,

thick

l i s t e d in the fir s t column of Table

I.

In

Impact Noise Rafings (INRI, fallowing the procedure given in Reference

2. The t h i r d column gives subjective comparisons of footstep noise

transmitted through each floor referred to that transmitted through the bare concrete slab.

PROPERTIES

OF

I

N

Two t y p e s of simulated floating floors with either concrete or

wood topping w e r e investigated. The concrete'topping w a s 1-318 in,

2

thick by 2 ft square precast concrete units (surface density = 16 l b / f t

1

a r r a n g e d to provide a 2 by

8

of (1) parquet flooring blocks, or ( 2 ) vinyl tile on 2 layers of 4 by 8 f t plywood.

An attempt was made to correlate the impact sound insulation of

the floating f l o o r s t e s t e d with physical properties of the sandwich

materials. Elasticity of the sandwich materials was measured by

utilizing a 3 - i n . square sample of the material in a spring-mass system. The oscillating m a s s , also 3 . in. square provided static loading.

The method used is essentially the same as that df Bach and G o s e l e (4) except that they used wax to adhere the sandwich material to the o s c i l -

lating mass. Far a spring-mass aystem the resonant frequency, f , is

determined by k (spring constant:)

and

k

of

The spring constant can then be converted info an elastic modulus by

considering area and thickness of the sample

k= E(elastic modulus) x S (area)

d (thickness) and

then

E

₌

The dynamic r i g i d i t y of a material

that

P r e l i m b a r y measurements showed that all materials w e r e n m - l k e a r and became stiffer with increasing load. All measurements w e r e made at a loading of 1/3 p s i . This was chosen to be the approximate

s t r e s s acting on the sandwich material during walking. The force includes both the weight of the female walker (125 lb) and the dead weight of the

topping. Normally, an adjustment would be in o r d e r to compensate far

the different surface weights of c u n c r e k and wood topping.

It was a s s u m e d ,

however, that the concrete, befng stiffer than W e w o o d Layer, distributes

the force of the walker over a larger area, resulting in approximately the

same stress on the sandwich material in either case,

Table

II

sandwich materials. Also included a r e damping factors obtained with the same samples, determined by observing the width of t h e resonance peak at the half-power points,

Figures

1,

insulation determined b female footstep noise and t h e tapping machine

5

with the parameter E / d obtained from measurements of physical p r o - perties of the sandwich material. The best correlation might have been expected to be w i t h the effective spring constant for the! fiateriaLs ( ~ / d ) ,

but it w a s found that ~ / gives d ~a better fit.

It

the

parameter c o r r e l a t e s better with the female footstep noise results than tvith either of the machine x a t i n g s. It is not known why floor constructions Nos. 11 and 17, which involve the _{same thickness of the s a m e sandwich} material, but different toppings, should differ appreciably when t e s t e d

with foots k p noise. REFERENCES

1. Qlynyk, D. Subjeclive Judgments of Footstep N o i s e Transmission

Through Floors. Journal of the Acoustical Society of America, V o l . 3 8 , 1 9 6 5 , p. 1035

-

2, Field and Laboratory Measurements of Air-borne and Impact Sound Transmission

.

3. h p a c t Noise C o n t r o l in Mult-ifamily Dwellings. Federal. Housing

Administration, Washington, D. D.

,

75

(19

W.

Elastizitatsrnoduls von

Tr

aus dem h s t i t u t fur technische Physik S h a g a r t , 1957,

No.

Translation available as The Determination of t h e Dynamic Modulus of Ela sticifqr of h p a c t Sound Insnlation Materials, Library Communication

No. 826

[Feb.

TABLE 1

SUMMARY

OF

FLOOR

F l o o r Construction Impact N o i s e Female Heelsr: Machine Rating

Rating Improvement over Based on Flat

Bare Concrete,

dB

d B

I . . . . . - . - - - . . . . .

4411.

bare

.slab

-

69

1

/#-in.

vinyl=asbesto

=

132 ib/ft3) bonded to b. c .

-

1 / 8 - i n . rubber tile (density

=

117

bonded to b. c . rn

18

3

116-in.

=

7 9

lb/f$)

b.

-

16

1/2-in. parquet wood block flooring

bonded t o b. c .

-

3

/16-in.

=

29.4

bonded

b.

-

1 /$-in,

114-in. plywood on 2 layers

of

roofing

518cin.

to furring bonded to

b.

114-in,

518-in.

to

1

12411,

renilient

rubber

on b.

+

d

-

-5

3 - =

+ - d G

0 5

2

;

"a;

2

2

2

-7

5

:

~4

F l o o r Construction Impact Noise Female Heels: Machine R a h g

Rating Improvement over Based on Flat

Bare Concrete, d B Spectzurn Rating, dB

15 1/8-in, vinyl-asbestos tiJ.e bonded to 1L/4-inm

plywood

an

to

114-in.

regular flexible polyurethane foam (density

=

1.4 lb/ft3) an

b.

c.

t

16.

1 318-in.

concrete on 114-in.

board (same material as

in No. 9 )

17.

1 318-in.

1-in.

(same

material

II)

on

+

5

18.

concrete on

layers

of

2-in.

corkboard(saxnemateria1asinNo. 1 ) o n b . c . + 8

19

3. 318-in.

concrete on 5/8-in.

wallboard (density

=

b.

-

2 0 .

1

318-in.

wallboard with

c r u m b s (118-in.

to

3116-in.

wallboard on b.

+

1

21.

1318-in.

on

material

(ll2-in.

with

asphalt to building aper (surface

density

E

F l o o r C o n s t r u c t i o n Impact N o i s e Female I-Ieels: Machine Rating Rating Improvement over B a s e d o n Flat

Bare Concrete,

dB

22. 1 318-in. precast concrete on 1-in.

cellular polystyrene (density

=

on b . c . 0

23. 1 3 18-in. precast concrete on 1 J8-in. (total thickness) ribbed rubber mat with

1132-in. -deep by 3 J16-in. -wide r i b s at

4f16-in.

=

0.75

-

6

2 4 .

114-in.

(surface density

=

b.

+

25. 1/8-in. lbop pile with 1/8-in. foam rubber backing v i s c o s e carpet (surface

density

=

0.33 ib/ft2) on b . c .

t

26. W o o l broadloom carpet with li4-in.

b.. c .

no underlay (surface density

=

+

THE FOLLOWING FLOOR CONSTRUCTIONS W E R E NOT INCLUDED

I

N

27.

118-in.

11441.

on

1-in.

sand

s

=

6

polyethylene

** C

.-

---

-

-

+

T y p e

s f T o p p i n g

for

F l o a t i n g

F l o o r

8

6

-

4

-

2

0

2

+ 4

6

8

10

I M P A C T

R A T I N G

F I G U R E

I

EM?

P A R A M E T E R

v s

I M P A C T N O I S E R A T I N G

I

4

I

I

-i

-i

3

4

3

i

s:

?

0 1 2

_E

11,000

m21

17

1

5

-I

-

B

li

of

T o p p i n g

for

F l o a t i n g

F l o o r

C o n c r e t e

m 1 8

"

Wood

1

E

100

1

I

1

I

I

I

I

I

I

1

I

I

4

I

I

I

68

6 6

64

62

60

58

5 6

5 2

50

4 8

46

M A C H I N E

R A T I N G B A S E D O N

R E F E R E N C E S P E C T R U M

F I G U R E

2

~

l

P A R A M E T E R

d

~

V S

FLAT S P E C T R U M

M A C H I N E

R A T I N G

5

10

15

FEMALE

HEELS:

D

MPROVEMENT

O V E R

B A R E

C O N C R E T E ,

dB

F I G U R E

3