Composite Vapor Barrier System for Contaminated Land
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Solution Overview
Problem
Existing vapor barrier technologies for contaminated land are costly, difficult to install, and often fail to adequately inhibit the migration of hazardous vapors, especially around penetrations and are susceptible to chemical degradation.
Innovation Solution
A composite membrane system comprising a base layer of high-density polyethylene (HDPE), a middle layer of latex modified asphalt, and a top layer of HDPE, which is applied directly to the ground surface before building construction to prevent vapor migration into indoor spaces, with the asphalt layer providing additional sealing and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin sheeting is used as vapor barrier, then barrier function is provided, but installation becomes very labor intensive requiring skilled technicians for seam welding and mechanical sealing
Solution Approach 1:
The patent changes the physical state and application method of the vapor barrier material from pre-formed sheets requiring welding to a liquid-applied coating that cures in place. This parameter change eliminates the need for skilled seam welding and mechanical sealing operations while maintaining barrier effectiveness.
Solution Approach 2:
The patent replaces the mechanical system of sheet overlay, welding, and sealing with a chemical/physical system where liquid coating penetrates and bonds to the substrate, forming an integral barrier that cures without mechanical joining operations.
2Ease of manufacture
If latex modified asphalt spray is used as low cost vapor barrier, then installation cost is reduced, but ability to inhibit volatile organic vapors is limited and material is degraded by chemicals
Solution Approach 1:
The patent creates a composite system where liquid-applied polymer-modified asphalt coating is applied over HDPE geosynthetic fabric. This composite structure combines the chemical resistance and vapor barrier properties of HDPE with the sealing and adhesion properties of polymer-modified asphalt, achieving both cost-effectiveness and chemical resistance.
Solution Approach 2:
The patent applies different materials with different properties to different locations/functions: HDPE fabric provides the primary vapor barrier and chemical resistance, while polymer-modified asphalt provides sealing at penetrations and bonding to concrete. Each material is optimized for its specific function.
3Reliability
If traditional vapor barrier methods are used, then barrier is provided, but penetrations through membrane require wrapping and mechanical binding which is time consuming
Solution Approach 1:
The patent replaces mechanical wrapping and binding of penetrations with a liquid-applied coating system that flows around and seals penetrations in place. The liquid coating cures to form an integral seal around conduits and penetrations without requiring mechanical fastening or wrapping operations.
Solution Approach 2:
The patent applies the liquid vapor barrier coating before concrete pouring and penetration installation, allowing the coating to penetrate and bond to the substrate in advance. This preliminary application creates a barrier that naturally seals around penetrations as they are installed, eliminating subsequent sealing operations.
4Reliability
If polyolefin sheeting is used, then vapor barrier function is achieved, but significant time is required for seam binding and welding by skilled technicians
Solution Approach 1:
The patent replaces mechanical sheet overlay and welding operations with liquid-applied coating that cures in place. This substitution eliminates the need for skilled technicians to perform time-consuming seam welding and binding operations, dramatically increasing installation productivity while maintaining continuous barrier integrity.
Solution Approach 2:
The patent changes the application method from installing pre-formed sheets that require joining to applying liquid coating that forms a continuous barrier without seams or joints. This parameter change eliminates the productivity bottleneck of seam welding while ensuring continuous sheet integrity.
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 composite membrane system effectively inhibits the upward migration of chemical vapors, is resistant to punctures and chemical breakdown, and is easier to install, making it a cost-effective solution for protecting building occupants from contaminated sites.
Implementation Method 1
a barrier beneath newly constructed buildings that will inhibit the upward migration of chemical contaminants into the construction materials and indoor air space of the structure
Implementation Method 2
The overlaps are then chemically sealed or heat welded to produce a continuous sheet
Implementation Method 3
Typically, the material is spayed onto the ground surface
Implementation Method 4
the asphalt may be applied over a typical geo-textile fabric, which serves to add tensile strength
Data Source
AI summary
A composite membrane comprises: a first layer of high-density polyethylene (HDPE) and a layer of asphalt applied over the first layer of HDPE. A second layer of HDPE sheeting is applied over the layer of asphalt. A method of creating a composite barrier to chemical vapors is also disclosed which comprises applying a base layer comprising high density polyethylene (HDPE); applying an asphalt layer over the base layer; and applying a top layer comprising HDPE over the asphalt layer.