Lightweight Concrete Using Waste Incinerator Ash
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Solution Overview
Problem
The use of waste incinerator ash in construction materials is hindered by concerns over heavy metal leaching and high pre-treatment costs, making it economically unattractive for civil engineering applications.
Innovation Solution
A method of manufacturing lightweight concrete by mixing waste incinerator ash with a binder and curing it, where the ash acts as an aerating agent and replaces traditional binder materials, reducing particle size and utilizing its metallic aluminum content to generate bubbles and lower density, thus reducing raw material costs and environmental concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If waste incinerator ash is used as aggregate in concrete, then the volume of waste is reduced and construction material is provided, but heavy metal leaching occurs and expansion cracking occurs due to reaction between metallic aluminum and cement
Solution Approach 1:
The invention converts the harmful metallic aluminum content in waste incinerator ash, which causes expansion and cracking when used as aggregate, into a beneficial aerating agent. By controlling the ash particle size to 500 μm or less, the metallic aluminum reacts with water and cement to generate fine bubbles that create a porous structure, transforming the harmful expansion into useful air entrainment that reduces concrete density and improves workability.
Solution Approach 2:
The invention changes the critical parameter of ash particle size to 500 μm or less. This size reduction transforms the behavior of metallic aluminum in the ash, enabling it to generate fine, uniformly distributed bubbles rather than causing coarse expansion and cracking. The particle size modification allows the metallic aluminum to serve as an effective aerating agent while preventing harmful macro-expansion.
2Object-affected harmful factors
If pre-treatment methods such as vitrification are applied to waste incinerator ash, then heavy metal leaching is reduced, but manufacturing cost increases significantly
Solution Approach 1:
Instead of using expensive pre-treatment methods like vitrification to remove or immobilize heavy metals, the invention accepts the metallic aluminum content as a beneficial aerating agent. This approach eliminates the need for costly pre-treatment processes while still producing safe and useful lightweight concrete, thereby resolving the contradiction between reducing harmful effects and maintaining economic feasibility.
Solution Approach 2:
The waste incinerator ash serves its own purpose by providing both the aggregate function and the aerating agent function. The metallic aluminum in the ash, which would normally require expensive treatment, automatically performs the useful function of air entrainment when particle size is controlled, making the ash self-sufficient and eliminating the need for additional costly pre-treatment steps.
3Ease of manufacture
If waste incinerator ash is used as aerating agent, then binder material cost is reduced, but particle size control is required to prevent expansion and cracking
Solution Approach 1:
The invention establishes a specific particle size parameter of 500 μm or less for waste incinerator ash to be used as aerating agent. This precise size control transforms the metallic aluminum behavior to generate fine bubbles uniformly distributed throughout the concrete, preventing the expansion and cracking that would occur with larger particles while enabling cost reduction by eliminating the need for expensive binder materials.
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 resulting lightweight concrete has a density of 200 kg/m³ to 1900 kg/m³, compressive strength of 0.5 MPa to 70 MPa, and thermal conductivity of 0.05 W/m-k to 1.3 W/m-k, making it suitable for insulation and structural uses while reducing disposal costs and environmental impact.
Implementation Method 1
utilizing its metallic aluminum content to generate bubbles and lower density
Implementation Method 2
the ash acts as an aerating agent and replaces traditional binder materials, reducing particle size and utilizing its metallic aluminum content to generate bubbles
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A method of manufacturing a lightweight concrete is provided. The method includes a) providing ash obtained from incineration of waste, the ash comprising at least about 0.1 wt% metallic aluminum; b) mixing the ash with a binder to form a mixture; and c) curing the mixture to obtain the lightweight concrete. Lightweight concrete and use of ash as an aerating agent such as an aerating agent in manufacturing of lightweight construction materials are also provided.