Surface-Coated TiO2 Concrete for NOx Degradation
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Solution Overview
Problem
Existing photocatalytic pavement technologies using TiO2 in cementitious materials suffer from low activity, high material consumption, and adverse effects on concrete properties, along with visual appearance issues and reduced NOx degrading performance due to high TiO2 loading and micron-sized particles.
Innovation Solution
A method involving the application of photocatalytic titanium dioxide particles dispersed in a continuous phase on the surface of concrete elements, with a silica compound to enhance NOx degrading properties and reduce material usage, maintaining performance despite humidity and weathering effects, using a binder-free composition that improves strength and visual appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TiO2 is incorporated in cementitious materials to produce photocatalytic pavement, then air purifying properties are obtained, but the product has low activity and high material consumption
Solution Approach 1:
The patent extracts TiO2 particles from the cementitious matrix and applies them as a separate surface coating layer. This separation allows the TiO2 to be concentrated at the surface where photocatalytic activity is needed, rather than being diluted throughout the bulk cement material, thereby reducing overall material consumption while maintaining air purifying capacity.
Solution Approach 2:
The invention applies TiO2 specifically at the surface layer of the pavement where pollutant contact occurs, rather than uniformly distributing it throughout the entire cementitious structure. This localized application optimizes photocatalytic activity at the critical interface with pollutants while minimizing material usage.
2Reliability
If TiO2 is incorporated in cementitous composition, then photocatalytic properties are achieved, but the overall properties of cementitous products such as strength are affected
Solution Approach 1:
The patent divides the photocatalytic function from the structural function by applying TiO2 as a separate surface coating rather than mixing it into the cementitious matrix. This segmentation allows the concrete to maintain its full structural strength while the surface layer provides photocatalytic activity, eliminating the compromise between strength and photocatalytic performance.
Solution Approach 2:
By extracting TiO2 from the cementitious composition and applying it as a surface layer, the invention removes the negative impact of TiO2 incorporation on concrete strength while preserving the desired photocatalytic properties at the surface.
3Reliability
If high loading of TiO2 and micron sized TiO2 is used, then photocatalytic capacity is increased, but the visual appearance of the product changes
Solution Approach 1:
The invention changes the particle size parameter of TiO2 from micron-sized to nano-sized particles. This parameter change allows achieving high photocatalytic capacity with much lower loading amounts, thereby preventing visual appearance changes while maintaining or enhancing NOx degrading performance.
4Reliability
If TiO2 is applied on concrete surface, then NOx degrading properties are obtained, but performance decreases due to humidity and weathering effects
Solution Approach 1:
The patent uses composite materials comprising TiO2 particles combined with hydrophobic substances or encapsulating materials. This composite structure protects the TiO2 from humidity and weathering effects while maintaining its photocatalytic activity, thereby extending the duration of effective NOx degrading performance.
Solution Approach 2:
The invention applies protective coatings or hydrophobic substances beforehand to shield the TiO2 particles from adverse environmental conditions such as humidity and weathering, preventing performance degradation before it occurs.
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 significantly enhances NOx degrading performance while reducing TiO2 usage, maintaining effectiveness over time and improving concrete resistance to humidity and weathering, with NOx degrading performance exceeding 30% as measured by ISO 22197-1, and maintaining visual and structural integrity.
Implementation Method 1
Photocatalytic compounds such as TiO2 can be used to produce air purifying building materials. TiO2 incorporated in building materials can remove significantly portions of NOx, SO2 and VOC (Volatile Organic Compound) pollutants
Data Source
AI summary
A method of applying a NOx degrading composition on a concrete element, including providing a concrete element having a surface, and applying a composition including photocatalytic titanium dioxide particles dispersed in a continuous phase on the surface of said concrete element. Also, a concrete element having NOx degrading properties. Also, a concrete element having photocatalytic titanium dioxide particles dispersed thereon.