Acoustical Concrete Masonry Unit
A The Acoustical Concrete Masonry Unit shall be the model DiffusorBlox® dB8S as manufactured by RPG® Diffusor Systems, Inc., Upper Marlboro, MD 20774. Tel: 301-249-0044, Fax: 301-249-3912.
B The Acoustical Concrete Masonry Unit shall conform to the following:
1. For hollow load bearing units, ASTM C-90 for grade N, Type I or Type II units with the exceptions noted herein.
2. For hollow non-load bearing units, ASTM C-129 for Grade N, Type I or Type II units, with the exceptions noted herein.
3. DiffusorBlox® constituent materials shall conform to the following ASTM:
a. Portland Cement: ASTM C-150
b. Blended Cements: ASTM C-595
c. Hydrated Lime, Type S: ASTM C-207+
d. Pozzolans: ASTM C-618
e. Aggregate: ASTM C-331 or C-33, based on local availability
C Other concrete unit constituents such as air-entering agents, pigments, water repellents, silica, etc. may be used provided their suitability for use in concrete has been established either by inclusion in ASTM Standards or through test and experience records substantiating that such particular mixtures and their proportions are not detrimental to the durability and/or performance of DiffusorBlox® units.
D The Acoustical Concrete Masonry Unit shall work on the one dimensional reflection phase grating principle, using an array of wells of equal width separated by dividers. The depths of the wells shall be based on the prime 7 quadratic residue theory sequence. A full sequence is achieved by alternating two types of block designated as Type A and Type B.
E Sound diffusion in the horizontal plane shall be provided by wells in the vertical position.
F Absorption coefficients and noise reduction coefficient for the product shall be measured by an independent, accredited NVLAP facility according to the test methods as defined by ASTM C 423 and ASTM E 795. Random incidence absorption coefficients for the product in a Type A mounting shall be as follows:
| 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | NRC | |
| Unfinished, stained, or lightly painted | 0.98 | 0.90 | 0.93 | 0.77 | 0.80 | 0.77 | 0.85 |
| Fully sealed | 0.76 | 0.51 | 0.57 | 0.34 | 0.24 | 0.26 | 0.41 |
G Diffusion Coefficients for the product shall be measured in accordance with AES-4id-2001. The normal incidence diffusion coefficients are listed below at octave-band centers. The mean and standard deviation (
)
of the 1/3-octave-band coefficients are also tabulated. | 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | MEAN | SD |
| 0.63 | 0.69 | 0.74 | 0.71 | 0.70 | 0.74 | 0.70 | 0.07 |
H Where fire rated assemblies are indicated, materials shall be tested by an independent, accredited NVLAP facility according to the test methods as defined by ASTM E 119 and NFPA 251.
I Inset insulation shall be semi-rigid fiberglass conforming to ASTM C 1071, having 6.0 lb. per cubic foot density, and a Class A fire rating, each individually shaped to conform to the concrete block cores. Fiberglass inserts shall be pre-installed at the block plant prior to delivery.
J The overall dimensions shall be 7-5/8"(H) x 15-5/8"(W) x 7-5/8"(D).
8'' Slotted CSI Specifications
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2000, RPG Diffusor Systems, Inc. |