EMSEAL
Expansion Joints and Pre-Compressed Sealants


 

 
Comparison of AS1530.4 “Methods for Fire Tests on Building Materials, Components and Structures” With UL2079 “Tests for Fire Resistance of Building Joint Systems” with Specific Focus on 2-Hour, Fire Rated Expansion Joints

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Abstract

The two standards are examined to assess how products evaluated to the UL2079 (North American) standard would be expected to perform when evaluated using the AS1530.4 (Australian/NZ) standard.

It was discovered that the AS1530.4 standard does not specifically address building expansion joints, and has no provisions for incorporating expansion joint movement into the overall fire rating. As such, the AS1530.4 standard would not be best suited for the evaluation of building joints such as structural expansion joint openings that are larger than control joints where little or no movement is expected.

The AS1530.4 standard has a somewhat more severe oven profile than the UL2079, but allows for a 2.5% deviation which would theoretically allow the UL2079 oven profile. An FEA model which closely correlates with actual UL2079 test data, modified to incorporate the AS1530.4 requirements, proves the materials tested under the UL standard would pass the slightly higher AS standard oven profile with a broad safety margin.

Systems passing AS1530.4 have not undergone any cycling component, and as such, it is unknown how cycling will affect the products FR performance.

Systems passing AS1530.4 are not tested at the maximum joint opening determined by the manufacturers’ published movement capability.

Systems passing AS 1530.4 were not tested at field-executed splices, and as such, it is unknown how the tested materials would perform where joined in the field.

Systems passing AS1530.4 in walls have not undergone a hose-stream test following the fire test to demonstrate the products ability to remain in place and resist impact from falling debris during a fire.

In most other aspects, it is felt that the two standards would provide a roughly equivalent predictor of protection.

 

Summary of Conclusions

As a result of this comparison, it was determined that systems passing UL2079 have been evaluated using criteria more suitable for moving, structural expansion joints than if they had been evaluated to AS1530.4.

It is the opinion of this study that the overall requirements of UL2079 exceed those of AS1530.4 and that specimens tested to the UL2079 standard would meet the requirements of the AS1530.4 standard.

 

Discussion

The Australian standard AS4072.1 “Components for the Protection of Openings in Fire-Resistant Separating Elements” is intended to be used in conjunction with AS1530.4  “Methods for Fire Tests on Building Materials, Components and Structures” which contains the procedures for the doing the evaluations.  UL2079 “Tests for Fire Resistance of Building Joint Systems”, is a North American standard promoted by Underwriters Laboratories which leverages previously accepted ASTM (American Society of Testing Materials) standards.

In both tests, the goal is to provide a uniform set of conditions to allow building designers, and manufacturers to determine the fire resistance of building components.

AS1530.4 is a more general standard than UL2079, including such items as structural elements (columns and trusses), walls, floors, roofs, door sets, shutters, glazing, air ducts, dampers, service penetrations and control joints.

AS4072.1 refers to a control joint as “A joint, between or within discrete elements of construction, that allows for relative movement of the elements”. This is closely analogous to UL2079 definition of a building joint system, although UL further stipulates that a control joint should not exceed 5/8” (16mm) in width. UL does not, however, stipulate that control joints cannot be qualified under UL2079.

In both tests, the main component is a timed exposure of the building element in question to heat, under controlled conditions created by a furnace. The furnace is operated in a fashion to achieve, within reasonable limits, a prescribed time-temperature curve. The elapsed time at which failure is seen is recorded.

The fire rating for AS1530.4 is called the Fire Resistance Level (FRL). It is designated in minutes, and is noted discretely for three performance criteria: structural adequacy, integrity, and insulation. For example a load bearing wall might have an FRL of 120/120/120 meaning it satisfies the standard to a minimum of 2 hours for all three criteria. Where a criterion is not applicable, the value is indicated with a dash. For example, a control joint, might have an FRL of --/120/120, since it is a non-load bearing element.

UL2079 provides a similar fire rating, as time to failure, usually provided in hours. The UL2079 rating includes a structural component, an integrity component, and an insulation component although it is not possible, usually, to separate them. A failure of integrity generally means a failure of insulation. It is not possible to have a 2 hour integrity rating and only a 1 hour insulation rating. The rating would be given as the lower of the two values: 1 hour. In this discussion, it is assumed that the joints in question are non-load bearing, so the structural component of both tests is not compared. 

Both standards list similar methods for determining integrity failure by testing any crack, fissure, or opening with a cotton pad. If the cotton pad ignites then the integrity portion of AS1530.4 is failed. In UL2079, if the cotton pad ignites, the entire test is failed and the time is noted.

Similarly for the insulation portion in AS1530.4, a failure is noted as an average unexposed temperature, as measured by thermocouples, of more than 140K above initial. Simultaneously, no single location should be more than 180K above the initial. UL2079 sets these limits at 139K and 181K respectively. When these values are exceeded in the AS1530.4 test, the insulation portion of the test is finished although the test can be continued for the other ratings. In UL2079, the test is finished.

AS1530.4 uses an oven profile described by the equation: T = 345log(8t+1)+20. UL uses the oven profile described in ASTM E-119 “Standard Test Methods for Fire Tests of Building Construction and Materials”. This profile produces higher temperatures initially, to approximately 30 minutes, but slightly lower temperatures from 30 minute onwards. At two hours, the UL2079 oven temperature is expected to be 1010C, while the AS1530.4 temperature is expected to be 1049C.Both standards make allowances for variation in temperature by stipulating that the area under the temperature-time curve be within certain allowances. At greater than 60 minutes, AS1530.4 allows the area under the curve to vary by not more than 2.5%. The area under the AS curve at the two hour mark is 108034 (Kelvin*minutes), while the area under the UL curve at the same time is 105420 K*m. This is a variation of 2.48% which is within the allowable deviations permitted by the AS1530.4 standard. Nevertheless, the higher temperatures seen in the AS oven profile necessitated further study, and this is addressed below in the FEA model.

The movement criteria stipulated in UL2079, create several additional requirements that have no corresponding requirement within AS1530.4. Since UL2079 is specifically designed to address the requirements of expansion joints, and AS1530.4 is not, this is to be expected. However, it is important to note that the cycling regime in UL2079, especially for cast in place elastomeric/intumescent mineral wools systems can severely degrade the integrity of specimen.

In UL2079, a building joint must be cycled between its minimum and maximum published movements prior to the fire test. The only exception to this occurs when the manufacturer states that the building joint has no movement capability.

There are three cycling levels that can be tested: thermal (Class I), wind loading (Class II), and seismic (Class III). UL defines these in terms of the cycling rate and number of cycles that the joint must endure prior to the fire test. For thermal cycling, the rate is 1 cycle (defined as nominal to minimum to maximum and back to nominal) per minute for 500 cycles. Wind loading is defined as 10 cycles per minute for 500 cycles, and the seismic rate is defined as 30 cycles per minute for 100 complete cycles. A product with a published movement must, at minimum, be tested to one of these levels, and if the seismic rate is desired must additionally be tested at the wind loading level. UL2079 also requires that the cycled product include at minimum one factory fabricated splice, and one field splice. UL2079 was specifically designed to address the movement cycle that building joints are expected to see in the field while remaining practical.  In this respect UL2079 is a far more stringent test than AS1530.4 and more relevant to the consideration of the use of materials in high-movement structural expansion joint openings.

Another key difference in UL2079, again regarding movement, is the requirement that all joints be fire tested at their maximum published movement after the cycling regime has been completed. In this respect too, the UL standard is more stringent than the AS standard as it is understood that the wider the product being tested, the more heat input goes into the product and less into the surrounding substrates, making the test more difficult to pass.

In vertical tests under UL2079, one additional criterion not specified in AS1530.4, is the Hose Stream Test. After the fire test has been successfully conducted, the assembly is subjected to a continuous stream of 30psi water directed from a 1.125” diameter orifice from a distance of 20 feet. The intent of this test is to assess the structural integrity of the assembly, not to specifically resist water penetration. If the specimen passes water through a tear, or crack, the entire assembly has failed the entire standard irrespective of the fact that the specimen may have passed the fire test.  In this respect as well, the UL standard is more stringent that the AS standard.

 

FEA Model

To address the issue of the slightly higher temperatures seen in the oven profile of the AS1530.4 standard as compared to the UL2079, a thermal FEA (Finite Element Analysis) was created.

The FEA model used was created to simulate the UL2079 test, and closely correlates with actual test data. This FEA model has been accepted by UL in various case judgments from which additional UL Listings have been granted.  Furthermore, this FEA model has been accepted by a prominent structural engineering firm in the United States (Simpson, Gumpertz & Heger) where it formed the basis for engineering judgments on applications where use of variations of tested products were approved in conditions not identically represented in actual laboratory testing.

 

The figure above shows EMSEAL’s EMSHIELD WFR2 (modeled in the higher-temperature, more severe horizontal-plane condition) at 2 hours when subjected to the AS1530.4 oven profile.

As expected temperatures on the unexposed side are slightly higher than with the UL2079 oven profile. At 2 hours, the highest unexposed side temperature is 424K vs. the UL test at 396K. The failure criteria in both UL and AS standards would be approximately 473K. This leaves a safety margin of approximately 50K.

Note that the above study was conducted at a joint width equal to the maximum joint movement capability of WFR2 (i.e at 5-inches (125mm)). A reduction in width would increase the available retardant density and lower temperatures would result.

 

Conclusion

The two standards cannot be directly compared in all aspects as UL2079 is specifically targeted at expansion joints, while AS1530.4 is a more general standard.

The two standards differ in five respects.  In one respect the AS standard is slightly more stringent than UL.  In four other respects, the UL standard is significantly more stringent that the AS standard.

The respect in which the AS1530.4 standard is slightly more stringent than the UL2079 standard is the 2.48% higher thermal input that may be achieved in accommodation of the variability of oven temperatures. An FEA model using the slightly higher oven profile required by the AS1530.4 standard, supports the claim that the material in question would pass the slightly higher AS temperature with a safety margin of nearly 50K.

The respects in which the UL standard is substantially more stringent than the AS standard and which make UL2079 simply a more appropriate test for structural expansion joint openings include the following criteria not present at all in AS1530.4,:

1)    the severity of the cycling requirements of UL2079

2)    the testing, under cycling as well as under the fire test of field-executed splices between product lengths

3)    the requirement to test at the product’s extreme maximum opening,

4)    the application after burning of a high-pressure hose stream test in wall joint conditions.

It is the opinion of this study that the overall requirements of UL2079 exceed those of AS1530.4 and that specimens tested to the UL2079 standard would meet the requirements of the AS1530.4 standard.

 

By: Bill Witherspoon, P.Eng., Professional Engineer and Vice President Operations, EMSEAL LLC.


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Last Modified: November 26, 2014

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