Fire-Resistant Expansion Joint With Elastomer Seal
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Solution Overview
Problem
Existing expansion joint systems in building construction lack simultaneous fire and water resistance, often compromising one property for the sake of the other, and are inadequate in accommodating thermal and seismic movements, leading to potential fire spread and water penetration issues.
Innovation Solution
An expansion joint system featuring a cover plate with a spline and open-celled foam infused with fire-retardant materials and layers of waterproof elastomer, which can be configured for asymmetrical or symmetrical water and fire resistance, and is designed to accommodate movement by being pre-compressed for easy installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional expansion joint systems use mineral wool or inorganic materials with field-applied liquid sealants, then fire resistance is improved, but water resistance deteriorates and the system cannot accommodate significant thermal movement
Solution Approach 1:
The patent uses a composite material system consisting of open-celled foam core infused with fire-retardant materials, coated with waterproof elastomer layers, and capped with metal plates. This composite structure simultaneously achieves fire resistance (through the fire-retardant infused foam), water resistance (through the waterproof elastomer coating), and movement accommodation (through the flexible foam core), resolving the contradiction between fire resistance and water resistance in traditional single-material systems.
Solution Approach 2:
The patent applies different materials with specific properties to different parts of the joint system: the foam core provides fire resistance and movement accommodation, the elastomer coating provides water resistance, and the metal plates provide structural stability and additional fire protection. This localized application of specialized materials allows each component to optimize its specific function while working together to solve the overall contradiction.
2Adaptability or versatility
If expansion joint systems are designed to accommodate thermal expansion and contraction movements, then movement flexibility is improved, but fire resistance deteriorates due to compromised coverage during cycling
Solution Approach 1:
The patent employs a dynamic design where the open-celled foam core can compress and expand to accommodate thermal movements, while the waterproof elastomer coating and metal plates maintain their protective functions throughout the movement cycle. The system is pre-compressed during installation to ensure adequate coverage is maintained even during maximum expansion, dynamically adapting to structural movements while preserving fire and water resistance.
Solution Approach 2:
The patent applies fire-retardant materials during the manufacturing process by infusing them into the foam core before installation, and pre-compresses the entire assembly during installation to ensure adequate coverage is established in advance. This preliminary action ensures fire protective coverage is maintained throughout the joint's operational life, even as the structure moves, without requiring field application that could compromise coverage.
3Temperature
If joint systems use monolithic or composite inorganic constructions, then fire resistance is improved, but ease of installation and accommodation of larger movements deteriorates
Solution Approach 1:
The patent segments the joint system into distinct functional components: a foam core infused with fire-retardant materials, waterproof elastomer coatings, and metal cap plates. These segmented components are manufactured separately and then assembled into a complete joint assembly, making the system easier to manufacture and install compared to monolithic inorganic constructions while maintaining fire resistance through the fire-retardant infused core.
Solution Approach 2:
The patent creates a composite construction combining organic foam material infused with inorganic fire-retardant additives, coated with elastomer, and capped with metal. This composite approach provides the fire resistance of inorganic materials while incorporating the ease of installation and movement accommodation of more flexible materials, resolving the contradiction between fire resistance and ease of installation for larger movement joints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides effective water tightness and fire resistance in both directions, meeting UL 2079 standards, while maintaining structural integrity and ease of installation, reducing the risk of fire spread and water penetration.
Implementation Method 1
open celled foam having a fire-retardant material infused therein
Implementation Method 2
layers of waterproof elastomer disposed thereon
Implementation Method 3
An intumescent material may be incorporated into the spline
Implementation Method 4
Each portion of the open celled foam is compressed between a respective face of the spline and a face of one of the coplanar substrates
Data Source
AI summary
An expansion joint system includes a cover plate; a spline attached to the cover plate; and foam having a fire retardant material included therein in an amount effective to pass testing mandated by UL 2079. The spline depends from the cover plate and is configured to be positioned in a gap between substrates such that the cover plate overlies the gap. The foam is compressible between a first face of the spline and one of the substrates and the foam is compressible between a second face of the spline and the other of the substrates, and the expansion joint system is configured to facilitate compression of the foam when installed between the substrates by repeatedly expanding and contracting to accommodate movement of the substrates; and the foam with the fire retardant material included therein is configured to pass the testing mandated by UL 2079.