Self-Healing Cement Admixture with Expanding Material
Solution Overview
Problem
Self-healing concrete requires improved post-cracking water-blocking performance that lasts for extended periods, as conventional measures are costly and time-consuming, and existing self-healing concretes do not maintain their self-healing capabilities over time.
Innovation Solution
A cement admixture comprising an expanding material and alumina-silicate with swelling properties, along with additional components like magnesium silicate, calcium phosphate, and a water reducing agent, which work together to repair cracks and maintain water-blocking performance by filling voids and forming stable hydrates that inhibit further hydration, thereby extending the self-healing capability of concrete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional measures (reparation, waterproofing, water-blocking) are taken to prevent water leakage, then water-blocking performance is improved, but construction cost increases and construction period is lengthened
Solution Approach 1:
The concrete performs self-repair by utilizing its own internal resources (water, hydratable cement, expanding materials) to automatically seal cracks without external intervention. The expanding material absorbs water at crack sites and expands to fill the cracks, while the hydratable cement provides binding material for repair, eliminating the need for external reparation operations.
Solution Approach 2:
The expanding material and hydratable cement are pre-included in the concrete mixture before cracking occurs. When cracking happens, these pre-positioned materials are immediately available to initiate the self-healing process, eliminating the need for subsequent reparation operations and reducing construction time.
2Reliability
If self-healing concrete is used to maintain water-blocking performance after cracking, then repair capability is improved, but the self-healing capability is not maintained for extended periods
Solution Approach 1:
The expanding material is pre-included in the concrete mixture, ensuring that the self-healing components are already in position and ready to act immediately when cracking occurs, rather than requiring subsequent addition of repair materials.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the concrete by incorporating specific expanding materials and controlling water-cement ratio, which changes the hydration characteristics and long-term durability of the self-healing process, enabling it to function effectively over extended periods.
3Reliability
If expanding material is added to cement composition to enable self-healing, then crack repair capability is improved, but flow property of concrete is reduced
Solution Approach 1:
The patent optimizes the water-cement ratio and incorporates water-reducing agents to compensate for the volume expansion effect of the expanding material. This adjusts the concrete's flow characteristics to maintain workability while preserving the self-healing functionality provided by the expanding material.
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 cement admixture effectively repairs cracks and maintains water-blocking performance for prolonged periods, ensuring the structural integrity and durability of concrete, even after extended periods, making it suitable for structures prone to water leakage like underground structures.
Implementation Method 1
the expanding material in the cement admixture of the invention generates hydrates with expanding properties, by hydration with water at the cracking sites that have formed in concrete, and the cracking sites can be filled by expansion of these hydrates
Implementation Method 2
the alumina-silicate with swelling properties included in the cement admixture absorbs moisture during the initial stage of hardening of the concrete
Implementation Method 3
the alumina-silicate in the cement admixture, which has swelling properties, generates crystalline hydrates by hydration with water and swells, combining with the expanding material hydrates to form insoluble precipitates
Implementation Method 4
combining with the expanding material hydrates to form insoluble precipitates
Implementation Method 5
the components that have eluted from the expanding material migrate into the cracking sites by diffusion, without being deposited in the concrete, to provide an excellent effect of selective filling of the cracking sites
Data Source
AI summary
It is an object of the invention to provide a cement admixture that can form concrete having a sufficient self-healing capability and satisfactorily maintaining its self-healing capability for prolonged periods. The cement admixture of the invention contains an expanding material and an alumina-silicate with swelling properties. The cement admixture is combined with cement to form a cement composition. The cement composition is mixed with water and an aggregate to provide concrete with an excellent self-healing capability.