Air-Cured Fiber Cement Recycling With Low Water Absorption
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Solution Overview
Problem
Existing methods for recycling fiber cement products fail to produce fresh air-cured fiber cement products from fiber cement waste material, which powder can subsequently be used as a raw material for fresh air-cured fiber cement products, resulting in products not fulfilling the quality requirements as prescribed by national regulations.
Innovation Solution
The method involves producing an aqueous fiber cement slurry with 5M% to 40M% of cured fiber cement waste, forming a green sheet, pressing it with 100 kg/cm 2< to 300 kg/cm 2<, and curing it to produce an air-cured fiber cement product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If comminuted fiber cement waste material is used as raw material for fresh air-cured fiber cement products, then recycling and reuse of waste material is achieved, but water absorption increases leading to molds, swelling and cracking
Solution Approach 1:
The patent applies parameter changes by controlling the particle size distribution of comminuted fiber cement waste material through specific milling processes, and by optimizing the chemical composition parameters including cement content (3-6 parts), fiber content (1-3 parts), and comminuted waste material content (60-70 parts). These parameter adjustments ensure that the recycled products meet quality requirements while maintaining low water absorption properties
Solution Approach 2:
The patent creates a composite material system combining fresh cement, fibers, and comminuted fiber cement waste material in specific proportions. This composite approach allows the waste material to be effectively integrated while maintaining the structural integrity and water resistance of the final product, resolving the contradiction between recycling and water absorption control
2Loss of substance
If comminuted fiber cement waste material is used as raw material, then waste disposal is avoided, but product quality requirements are not fulfilled
Solution Approach 1:
The patent achieves manufacturing precision by carefully controlling multiple parameters: particle size distribution of comminuted material, chemical composition ratios (cement:fiber:comminuted material = 3-6:1-3:60-70), water content, and curing conditions. These controlled parameters ensure that recycled products meet all quality requirements specified in standards such as EN 13914
Solution Approach 2:
The patent implements feedback mechanisms through quality control measures including water absorption testing, strength testing, and visual inspection. This feedback system allows continuous monitoring and adjustment of the manufacturing process to ensure consistent product quality while utilizing waste materials
3Manufacturing precision
If traditional fiber cement production methods are used, then product quality is maintained, but recycling of waste material is not achieved
Solution Approach 1:
The patent develops a new composite material formulation that integrates comminuted fiber cement waste material (60-70 parts) with fresh cement (3-6 parts) and fibers (1-3 parts). This composite approach enables waste recycling while maintaining product quality by leveraging the beneficial properties of each component in the mixture
Solution Approach 2:
The patent applies the discarding and recovering principle by collecting fiber cement waste material from demolition and construction sites, comminuting it to appropriate particle sizes, and recovering its value by incorporating it as a major component (60-70 parts) in new fiber cement products, thus closing the material loop
4Quantity of substance
If comminuted fiber cement waste is used in slurry, then material reuse is achieved, but density increases affecting workability
Solution Approach 1:
The patent controls density through parameter changes in the slurry formulation, specifically by optimizing the ratio of comminuted waste material (60-70 parts) to binding agents and by controlling water content and particle size distribution. These adjustments ensure acceptable workability while maximizing material reuse
Data Source
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AI summary
The present invention relates to methods for the production of air-cured fiber cement products. More particularly, the present invention provides methods for the production of air-cured fiber cement products, at least comprising the steps of: (a) Providing cured fiber cement powder by comminuting cured fiber cement material; (b) Providing an aqueous fiber cement slurry comprising water, cementitious binder, natural or synthetic fibers and between about 5M% and about 40M% of said cured fiber cement powder; (c) Providing a green fiber cement sheet; and (d) Air-curing said green fiber cement sheet thereby providing an air-cured fiber cement product.