Fibre Reinforced Cement Water Resistance via Air-Curing
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Solution Overview
Problem
Fibre reinforced cement articles face issues with efflorescence and darkening due to water absorption, particularly at cut edges and drilled holes, which are not adequately addressed by existing treatments, leading to labour-intensive and inefficient water repellent applications that fail to prevent water penetration and impair cement hardening.
Innovation Solution
A process involving air-curing of fibre reinforced cement articles at 45°C to 75°C for 5 to 10 hours, followed by application of a non-aqueous water repellent composition comprising silanes and siloxanes to create a water impermeable zone, and a translucent coating to protect the surface without additional on-site treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water repellent agent is sprayed on the fibre cement sheet during formation, then water resistance is improved, but cement hardening is impaired and efflorescence problems occur
Solution Approach 1:
The water repellent treatment is applied after air-curing (5-10 hours at 45-75°C) rather than during formation. This preliminary action sequence allows cement to harden first, then provides water resistance without interfering with hardening process, eliminating the contradiction between water resistance and cement hardening
Solution Approach 2:
The patent changes the timing parameter of water repellent application from during formation to after air-curing. This parameter change resolves the contradiction by allowing cement to complete hardening before water repellent is applied, preventing impairment of strength while maintaining water resistance
2Reliability
If edges and drilled holes are treated with sealer or water repellent agent on works site, then water penetration is reduced, but labour intensity increases and treatment is often incomplete
Solution Approach 1:
The water repellent treatment is performed in advance during manufacturing after air-curing, before the product reaches the works site. This preliminary action eliminates the need for labour-intensive on-site treatment of edges and holes, reducing installation complexity while maintaining water penetration resistance
Solution Approach 2:
The product is pre-treated with water repellent during manufacturing, making it self-prepared for water resistance without requiring additional treatment during installation. The product serves its own protection needs before reaching the user, eliminating dependency on manual on-site treatment
3Illumination intensity
If translucent coating is applied on front surface, then decorative appearance is improved, but water penetration through cut edges and drilled holes causes dark zones
Solution Approach 1:
The water repellent treatment is applied after air-curing and before translucent coating application. This preliminary action ensures that the substrate is protected against water penetration before the translucent coating is applied, preventing dark zones while maintaining the decorative translucent appearance
Solution Approach 2:
The water repellent treatment is specifically applied to areas prone to water penetration (edges and drilled holes) after air-curing. This local quality approach provides targeted protection where water penetration occurs, preventing dark zones in these critical areas while maintaining overall translucent appearance
4Strength
If autoclaving is used instead of air-curing, then strength is increased, but carbonation attacks crystalline structure and causes shrinkage
Solution Approach 1:
The patent changes the curing method from autoclaving to air-curing at controlled temperatures (45-75°C) for 5-10 hours. This parameter change avoids the carbonation attack that occurs with autoclaving, maintaining crystalline structure stability while still achieving sufficient strength for the application
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 process results in fibre reinforced cement articles that resist rain exposure without dark zones, maintaining appearance and strength, while reducing energy and labour costs, and ensuring deep penetration of the water repellent agent for effective protection.
Implementation Method 1
the water repellent composition comprising silanes and siloxanes is applied on the front surface... ensuring deep penetration of the water repellent agent
Implementation Method 2
a translucent coating composition is applied on the front surface of said fibre reinforced cement article, which is provided with said water repellent composition
Implementation Method 3
air-curing said fibre reinforced cement article at a temperature from 45°C to 75°C during a time period from 5 to 10 hours
Data Source
AI summary
Process for manufacturing fibre reinforced cement articles comprising forming a fibre reinforced cement article, air-curing of said fibre reinforced cement article at a temperature from 45°C to 75°C during a time period from 5 to 10 hours, applying a water repellent composition on a front surface of said fibre reinforced cement article, applying a translucent coating composition on said front surface of said fibre reinforced cement article provided with said water repellent composition, film forming and drying the translucent coating composition.