Fire Resistance


The United States has the highest rate of deaths by fire in the world. Approximately 5,300 people die in fires and another 29,000 are injured annually. Furthermore, more than 100 fire fighters die each year fighting fires. As a matter of fact, fire kills more Americans than all other natural disasters combined. Our homes, including multi-family dwellings, are the most vulnerable (more than 80% of all fire deaths occur in residences).

How can the most modern society in the world today have such dismal fire-death statistics? The answer is because all too often we do not utilize building designs that take advantage of fire detection (alarms), fire suppression (sprinklers) and fire containment (non-combustible fire walls). Alarms and sprinklers are effective but they do not always work. When they don't work as expected, then fire damage is extensive and deadly because, for economical considerations, fire containment is not part of the fire-protection plan.

Life-safety is paramount but so is property preservation. The costs attributed to fires that are protected only by sprinklers are disastrous. Water damage can be as extensive as fire damage. The smart design is one that considers the complete protection of both fire suppression and fire containment. When you contain the fire to the area of origin, everyone and everything else is fully protected.

Witelite by Tarmac has the highest fire ratings of any other lightweight aggregate. Masonry walls are fire tested using the American Society of Testing Materials (ASTM) test procedure E-119. Recent tests by Underwriters Laboratories have shown that Witelite by Tarmac can be blended with sand up to 50% by volume and still maintain fire ratings. The blending of aggregates allows economy and a choice of textures.


A Specifiers Guide To Identifying

Fire Rated Concrete Masonry Units


In order to establish compliance to specified fire ratings for concrete masonry units (CMU's), the following need to be considered:

1. The equivalent thickness of the CMU. The only valid procedure to establish the equivalent thickness of a CMU is by using test procedure ASTM C-140 (Standard Test Methods of Sampling and Testing Concrete Masonry Units). Every block manufacturer should have test results showing the equivalent thickness of each unit they supply.

 

ACI 216.1 (Standard Method for Determining Fire Ratings of Concrete and Masonry Assemblies), has been adopted by the new International Building Code (IBC) that will go into effect in early 2000 A.D. Chapter 3 of ACI 216.1 provides a chart (see Pages 2.5 and 2.6) identifying the types of aggregates used to manufacture CMU's and the fire ratings for each of the aggregates. The blending of aggregates is acceptable (and common), however, the fire ratings will need to be established using the calculation method.

EXAMPLE AND CAUTIONS:

Example: An 8"x8"x16" CMU is used in a construction project and the specifications require a two hour fire rating for the block. The manufacturer should be required to submit a test report establishing the equivalent thickness of the 8 inch unit being supplied. Most 8"x8"x16" CMU's will have an equivalent thickness of 3.8 inches to 4.0 inches.

Cautions:

an 8 inch CMU will not meet a two hour requirement unless the equivalent thickness is

4.2 inches or greater.

Listed below is a suggested specification language designed to put the responsibility to accurately comply with fire rating requirements on the block manufacturer. It is an example of a section that can be added to a firm's standard specifications to assure compliance with required fire ratings. The section numbers may vary according to each firm's numbering format.



04200 UNIT MASONRY

04204 Fire Rated Concrete Masonry Units

4.01 Fire ratings for concrete masonry units will be considered being in compliance when:

4.01.1 The CMU has been certified through ASTM E-119 testing, or

4.01.2 The CMU has been certified through the equivalent thickness method contained in Chapter 3 of ACI 216.1 or NCMA TEK 7-1A. (These requirements apply to blended and single aggregate CMU's).

4.01.2.1 For fire rated CMU's that are manufactured with blending two or more aggregates under the requirements of 2.01.2, blending percentages must be established by determining the dry-rodded weights of the aggregates rather than the damp-loose weights (as weighed in the batching process).

4.01.2.2 The percentage of each aggregate (dry-rodded weight) will be reported in the concrete masonry submittal.

4.02 The equivalent thickness of each fire rated block will be established by ASTM C-140. Verification of the equivalent thickness of fire rated CMU's will be supplied by an independent testing laboratory and submitted in the concrete masonry submittal.



Concrete Masonry Units Equivalent

Thickness Requirements

For Fire Ratings When Blending Primary Aggregates With Sand As Per ACI 216.1

100% Single Aggregate Minimum Equivalent Thickness (Inches) Required
(No Blending) 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

4.70

5.10

5.90

6.20

4.40

4.80

5.50

5.80

4.00

4.40

5.00

5.30

3.60

4.00

4.50

4.80

3.20

3.60

4.00

4.20

2.70

3.30

3.40

3.60

2.10

2.60

2.70

2.80

1.50

1.80

1.90

2.00

80/20% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 20% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.00

5.32

5.96

6.20

4.68

5.00

5.56

5.80

4.26

4.58

5.06

5.30

3.84

4.16

4.56

4.80

3.40

3.72

4.04

4.20

2.88

3.36

3.44

3.60

2.24

2.64

2.72

2.80

1.60

1.84

1.92

2.00

70/30% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 30% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.15

5.43

5.99

6.20

4.82

5.10

5.59

5.80

4.39

4.67

5.09

5.30

3.96

4.24

4.59

4.80

3.50

3.78

4.06

4.20

2.97

3.39

3.46

3.60

2.31

2.66

2.73

2.80

1.65

1.86

1.93

2.00

60/40% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 40% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.30

5.54

6.02

6.20

4.96

5.20

5.62

5.80

4.52

4.76

5.12

5.30

4.08

4.32

4.62

4.80

3.60

3.84

4.08

4.20

3.06

3.42

3.48

3.60

2.38

2.68

2.74

2.80

1.70

1.88

1.94

2.00



* Important Notice - All blending percentage calculations are based on aggregates being batched by volume rather than by weight. The dry-rodded weight of the aggregate must be established in order to accurately calculate the volume.

 
50/50% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 50% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.45

5.65

6.05

6.20

5.10

5.30

5.65

5.80

4.65

4.85

5.15

5.30

4.20

4.40

4.65

4.80

3.70

3.90

4.10

4.20

3.15

3.45

3.50

3.60

2.45

2.70

2.75

2.80

1.75

1.90

1.95

2.00


40/60% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 60% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.60

5.76

6.06

6.20

5.24

5.40

5.68

5.80

4.78

4.94

5.18

5.30

4.32

4.48

4.68

4.80

3.80

3.96

4.12

4.20

3.24

3.48

3.52

3.60

2.52

2.72

2.78

2.80

1.80

1.92

1.96

2.00

30/70% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 70% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.75

5.87

6.11

6.20

5.38

5.50

5.71

5.80

4.91

5.03

5.21

5.30

4.44

4.56

4.71

4.80

3.90

4.02

4.14

4.20

3.33

3.51

3.54

3.60

2.59

2.74

2.77

2.80

1.85

1.94

1.97

2.00

20/80% Blending* Minimum Equivalent Thickness (Inches) Required
Aggregate Plus 80% Sand 4 hr 3.5 hr 3hr 2.5 hr 2 hr 1.5 hr 1hr 0.5 hr
Pumice or Expanded Slag

Expanded Clay, Shale, Slate

Limestone or Cinders or Slag

Calcareous or Siliceous Gravel

5.90

5.98

6.14

6.20

5.52

5.60

5.74

5.80

5.04

5.12

5.21

5.30

4.56

4.64

4.74

4.80

4.00

4.08

4.16

4.20

3.42

3.54

3.56

3.60

2.66

2.76

2.78

2.80

1.90

1.96

1.98

2.00


* Important Notice - All blending percentage calculations are based on aggregates being batched by volume rather than by weight. The dry-rodded weight of the aggregate must be established in order to accurately calculate the volume.

 

Determining The Fire Resistance Of

Concrete Masonry Assemblies

 

FIRE RESISTANCE RATINGS

The fire resistance rating of concrete masonry elements can be determined by two methods:

ASTM E-119 tests full walls under fire conditions. It is an expensive procedure that is generally used as a research tool rather than a compliance test. Because of the vast number of ASTM E-119 testing programs using a variety of aggregates, there is sufficient data available to support an accurate calculation method for determining the fire resistance ratings of concrete masonry wall systems.

CALCULATING FIRE RESISTANCE

Extensive testing has established a relationship between fire resistance and the physical properties of concrete masonry units. This relationship provides the basis for calculating fire ratings based on the equivalent thickness of the masonry unit and the types of aggregates used in the production of the unit. This calculation can even be made when the different aggregates are blended together.


To calculate how much equivalent thickness of concrete masonry (with two or more blended aggregates) is needed for a desired fire rating, use the following example:

What equivalent thickness would be needed for an 8"x8"x16" block manufactured using Witelite pumice (50% by volume) and siliceous sand (50% by volume) to meet a tow hour fire-resistive rating?

Equivalent thickness of Witelite (2 hr) = 3.2 in.

Equivalent thickness of sand (2 hr) = 4.2 in.

Then: (3.2 x 0.50) + (4.2 x 0.50) = 3.7 in

Calculations show that a 3.7 inch equivalent thickness would be needed to provide a two-hour rated block made using 50% Witelite pumice and 50% sand measured by volume.

NOTE:

Underwriter Laboratories tested a 50% Witelite pumice and sand blend 8 inch unit on July 17, 1998 using the E-119 test method. The test verified that it exceeded a two hour fire rating. Testing a total of six different walls with different blending ratios ratified the calculation method of determining fire ratings.


EQUIVALENT THICKNESS

The equivalent thickness of a concrete masonry unit is determined through testing using ASTM C-140, Standard Methods of Sampling and Testing Concrete Masonry Units. For example, not all 8"x8"x16" concrete blocks have the same equivalent thickness. The equivalent thickness may vary depending on the core configuration, web thickness, and faced-shell thickness. Table 1 shows the equivalent thickness of typical concrete masonry units; however, for fire resistance ratings, it is important to know the precise equivalent thickness of a specified block. The concrete block supplier can be requested to submit test results that will establish the equivalent thickness of any CMU furnished for any job.

 
Table 1 - Equivalent Thickness of Typical Concrete Masonry Units (Inches)
Nominal

Width (In.)

Typical Hollow Units 75%

Solid

100%

Solid

4

6

8

10

12

2.7

3.1

3.9

5.0

5.5

2.7

4.2

5.7

7.2

8.7

3.6

5.6

7.6

9.6

11.6

 

SOLID GROUTED CONSTRUCTION

The equivalent thickness of concrete masonry units which are solidly grouted will be considered the same as the actual measured width of the unit.

FILLING CELLS WITH LOOSE FILL MATERIAL

If the cells of hollow unit masonry are filled with approved materials, the equivalent thickness of the assembly can be considered the same as the actual thickness. Approved loose materials will be dry sand, pea gravel, crushed stone, pumice, scoria, expanded shale, clay, or slate, expanded flyash, perlite, and vermiculite.

REFERENCES:

NCMA TEK 7-1, ACI 216.1, ASTM E-119

Calculating Mix Designs For Fire

Rated Concrete Masonry Units

Using the calculation method for determining the fire resistance of concrete masonry units requires three things: (1) the exact equivalent thickness of the unit, (2) the type of aggregate(s) being used, and (3) the dry-rodded weight of the aggregate(s). Concrete masonry unit producers generally do not perform daily tests to determine the dry-rodded weight of the aggregates being used. Even weekly testing will not predict the amount of moisture present on the day the materials are being used. Dry spells and rain will affect the moisture daily. That being the case, estimating the moisture content of aggregates can be an acceptable practice only if the estimates are conservative.

Lightweight aggregates will generally hold more moisture than normal weight aggregates. A 20% moisture content is common if the lightweight aggregate is exposed to continued wet weather. This guide allows the block producer to assume the worst-case moisture content of aggregates based on conservative and safe aggregate blending ratios.

MIX DESIGN ASSUMPTIONS

1. Witelite aggregate - assume 54 pcf dry-rodded weight and 20% moisture content.

2. All limestone aggregates - assume 101 pcf dry-rodded weight and 12% moisture content.

3. All calcareous and siliceous aggregates - assume 103 pcf dry-rodded weight and 4% moisture content.

EXAMPLE OF CALCULATIONS

(Example: 50% Witelite and 50% sand CMU for a two hour fire rated block)

Cement - 750 lbs.

Witelite - 2,500 lbs. (w/moisture), moisture content - 20%

Sand - 4,100 lbs. (w/moisture), moisture content - 4%

To calculate dry weight of Witelite: 2,500 1.20 = 2,080 lbs. dry-rodded weight

To calculate dry weight of sand: 4,100 1.04 = 3,940 lbs. dry-rodded weight

Dry-rodded weight of Witelite - use 54 pcf

Dry-rodded weight of sand - use 103 pcf

Aggregate to Cement Ratio (Individual Aggregates)

750 lbs. cement 94 pcf = 7.98 cu. ft.

2,080 lbs. Witelite 54 pcf = 38.58 cu. ft.

4,100 lbs. sand 103 pcf= 38.27 cu. ft.

Ratio = 38.58 cu. ft. (Witelite) 7.98 cu. ft. cement = 4.84

38.27 cu. ft. (sand) 7.98 cu. ft. cement = 4.80

Proportions = 1: (4.84 + 4.80) = 9.63 4.84 9.63 = 50.26% 4.80 9.63 = 49.84%

Percentage of Aggregate (based on cu. ft. - dry-rodded weight)

Witelite - 50.26% (50%)

Sand - 49.84% (50%)

MIX DESIGN AS WEIGHED IN THE SCALE HOPPER

Witelite - 2,500 lbs.

Sand - 4,100 lbs.

Cement - 750 lbs.

Totals - 7,350 lbs.

PLANT MANAGERS WORKSHEET

This calculation can be performed automatically using a lotus or excel worksheet. Please refer to the front of this binder for the disk.

BASIC ASSUMPTIONS

Witelite maximum moisture - 20%

Sand maximum moisture - 4%

Limestone maximum moisture - 12%

Granite screens, gravel moisture - 4%

Dry-rodded weight of Witelite - 54 pcf

Dry-rodded weight of Sand - 103 pcf

Dry-rodded weight of Limestone - 101 pcf

Dry-rodded weight of Gran./Gravel - 106 pcf  

SUGGESTED STARTING POINTS FOR CALCULATIONS

(Witelite And Sand)

50% Witelite - 50% Sand blend

Witelite - 2,500 lbs. (with moisture)

Sand - 4,100 lbs. (with moisture)

Cement - 750 lbs.

70% Witelite - 30% Sand blend

Witelite - 2,500 lbs. (with moisture)

Sand - 1,800 lbs. (with moisture)

Cement - 700 lbs.

60% Witelite - 40% Sand blend

Witelite - 2,500 lbs. (with moisture)

Sand - 2,700 lbs. (with moisture)

Cement - 750 lbs.

80% Witelite - 20% Sand blend

Witelite - 2,500 lbs. (with moisture)

Sand - 1,050 lbs. (with moisture)

Cement - 650 lbs.

CALCULATION PROCEDURE

To calculate dry weight of Witelite: lbs. 1.20 = lbs. dry

To calculate dry weight of Sand: lbs. 1.04 = lbs. dry

To calculate dry weight of Limestone: lbs. 1.12 = lbs. dry

To calculate dry weight of Granite

screens, gravel: lbs. 1.04 = lbs. dry

AGGREGATE TO CEMENT RATIO

(Individual Aggregates)

lbs. Cement 94 pcf = cf

lbs. Witelite 54 pcf = cf

lbs. Sand 103 pcf = cf

lbs. Limestone 104 pcf = cf

lbs. Gran./Gravel 106 pcf = cf

RATIOS

cf Witelite cf cement = a.

cf Sand cf cement = b.

cf Limestone cf cement = c.

cf Gran./Gravel cf cement = d.  

PROPORTIONS

(a. + b. + c. + d. ) = t. (total)

a. t= %,

b. t= %,

c. t= %,

d. t= %.

PERCENTAGE OF AGGREGATE

(Based On Cu. Ft.)

EQUIVALENT THICKNESS CALCULATIONS

(For A Two Hour Rating)

Witelite 3.2 x (% of total agg.) = in

Sand 4.2 x (% of total agg.) = in

Limestone 4.0 x (% of total agg.) = in

Gran./Gravel 4.2 x (% of total agg.) = in

Total Equivalent Thickness Rating = in  

MIX DESIGN AS WEIGHED IN HOPPER

(With Moisture)

Witelite lbs.

Sand lbs.

Limestone lbs.

Gran./Gravel lbs.

Cement lbs.

lbs. total batch

 

1998 Underwriters Laboratories ASTM E-119 Fire Tests

Tarmac America, Inc. July 13-17, 1998


Block Tested Percent Aggregate Blend Equivalent Thickness (Inches) Percent Solid Target Duration Of Test Maximum Average Temperature To Pass Maximum Single Point Temperature To Pass Actual Average Time/Temp. Actual Single Point Time/Temp.
6x8x16



8x8x16





8x8x16





8x8x16





8x8x16

70% Pumice

30% Sand



60% Pumice

40% Sand



60% Pumice

40% Sand



60% Pumice

40% Sand



50% Pumice

50% Sand

4.6





3.8





4.93





5.9





3.8

82%





50%





65%





77%





50%

3 hr.

(180 min.)



2 hr.

(120 min.)



3 hr.

(180min.)



4 hr.

(240 min.)



2 hr.

(120 min.)

Ambient + 250 D

334 Degrees



Ambient + 250 D

330 Degrees



Ambient + 250 D

332 Degrees



Ambient + 250 D

332 Degrees



Ambient + 250 D

333 Degrees

Ambient + 325 D

409 Degrees



Ambient + 325 D

405 Degrees



Ambient + 325 D

407 Degrees



Ambient + 325 D

407 Degrees



Ambient + 250 D

408 Degrees

3 hr. 28 min.

334 Degrees



2 hr. 21 min.

330 Degrees



2 hr. 15 min.

332 Degrees



4 hr. 30 min.

272 Degrees



2 hr. 7 min.

333 Degrees

3 hr. 46 min.

409 Degrees



2 hr. 25 min.

405 Degrees



3 hr. 30 min.

407 Degrees



4 hr. 30 min.

299 Degrees



2 hr. 6 min.

408 Degrees

8x8x16 100% Pumice 3.8 50% 2 hr.

(120 min.)

Ambient + 250 D

330 Degrees

Ambient + 325 D

405 Degrees

2 hr. 52 min.

330 Degrees

2 hr. 50 min.

405 Degrees




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