Low Permeability Cementitious Product for PFAS Containment
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Solution Overview
Problem
Existing methods for containing Per- and Polyfluoralkyl Substances (PFAS) within cementitious products are impractical for large-scale projects and do not effectively prevent PFAS leaching from concrete and similar materials.
Innovation Solution
A method involving the formation of a cementitious slurry with specific additives such as siliceous pozzolans, plasticizers, and crystalline growth waterproofing compounds, which results in a low permeability cementitious product that significantly reduces or prevents PFAS leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cementitious materials are used to contain PFAS, then the materials are porous and allow PFAS to leach out, but adding more porous materials increases permeability and reduces containment effectiveness
Solution Approach 1:
The patent changes the permeability parameter of the cementitious material from high (conventional) to low (below 10^-8 m/s) by adding specific additives including siliceous pozzolans, plasticizers, and crystalline growth waterproofing compounds. This parameter change transforms the material from PFAS-permeable to PFAS-impermeable, effectively preventing leaching while maintaining containment reliability.
Solution Approach 2:
The patent creates a composite cementitious material by combining conventional cement with specific additives (siliceous pozzolans, plasticizers, crystalline growth waterproofing compounds). This composite approach maintains the structural properties of cement while adding impermeability characteristics that prevent PFAS leaching, resolving the contradiction between containment effectiveness and harmful leaching.
2Reliability
If additives are added to reduce permeability and prevent PFAS leaching, then containment effectiveness improves, but the complexity of the cementitious product increases
Solution Approach 1:
The patent employs multi-functional additives that simultaneously achieve multiple objectives: siliceous pozzolans reduce permeability and enhance strength, plasticizers improve workability and reduce water demand, and crystalline growth compounds seal pores. This multi-functionality approach prevents PFAS leaching while maintaining relatively simple formulation and construction processes, mitigating the complexity increase.
3Reliability
If the permeability is reduced to prevent PFAS leaching, then containment effectiveness improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates impermeability-enhancing additives into the cementitious mix during the initial manufacturing process, before the material is placed and cured. This preliminary action ensures that the low permeability structure is formed during mixing and placement, avoiding the need for complex post-manufacturing treatments or procedures, thereby maintaining ease of manufacture while achieving effective PFAS containment.
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 method effectively contains PFAS within the cementitious product, reducing leaching by at least 70% compared to untreated materials, while maintaining high compressive strength suitable for civil engineering and construction projects.
Implementation Method 1
adding one or more of: siliceous pozzolans; plasticizer(s); or crystalline growth water-proofing compound(s), in an amount sufficient to produce a cementitious product comprising a coefficient of permeability of at or below 10−8 m/s
Data Source
AI summary
The invention provides a method of containing PFAS within a low permeability cementitious product, the method comprising: forming a cementitious slurry, the cementitious slurry comprising: cement; water; aggregate; and allowing the cementitious slurry to cure and thereby form a cementitious product; wherein one or more of the water and the aggregate is contaminated with PFAS; and further wherein the method comprises adding one or more of: siliceous pozzolans; plasticizer(s); and crystalline growth water-proofing compound(s), in an amount sufficient to produce a cementitious product comprising low water permeability, the low water permeability substantially preventing leaching of PFAS.