Concrete Admixture With Recycled Superabsorbent Polymers for Internal Curing
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Solution Overview
Problem
Existing concrete admixtures face challenges in reducing self-desiccation and autogenous shrinkage, leading to stress cracks and reduced durability, especially in high-performance concrete, while also contributing to a high carbon footprint due to fossil fuel-derived materials.
Innovation Solution
A cement admixture using a mixture of silica-based binders and recycled waste materials, including superabsorbent polymer and cellulosic particles from post-consumer and post-manufacturing waste, such as disposable diapers, to create a curing agent that absorbs and releases water during curing, enhancing strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional admixtures use fossil fuel-derived materials, then they can provide basic curing functionality, but they increase the carbon footprint and cost
Solution Approach 1:
The patent converts waste materials (harmful to environment) into beneficial curing agents for concrete. Specifically, it uses waste cooking oil to synthesize biobased surfactants and combines them with biobased superabsorbent polymers, transforming environmental pollutants into functional components that reduce carbon footprint while maintaining curing effectiveness.
Solution Approach 2:
The patent changes the chemical composition parameters of conventional admixtures by replacing petroleum-derived surfactants with biobased alternatives. The surfactant is synthesized from waste cooking oil through chemical modification, changing the source material parameter from fossil fuel to renewable waste resource, thereby reducing carbon footprint while preserving interfacial adhesion functionality.
2Strength
If concrete mixtures use less water for high performance, then they achieve higher strength, but they undergo self-desiccation and autogenous shrinkage
Solution Approach 1:
The patent introduces biobased superabsorbent polymers as intermediary agents that mediate between the limited water available and the cement hydration process. These polymers absorb excess water during mixing, then gradually release it during curing, acting as a buffer that prevents self-desiccation and maintains volumetric stability in low-water high-performance concrete mixtures.
Solution Approach 2:
The patent performs preliminary water management by incorporating superabsorbent polymers that pre-absorb water during mixture preparation. This preliminary action stores water in a reservoir that can be tapped later during curing, preventing autogenous shrinkage before it occurs by ensuring water availability during the critical hydration phase.
3Productivity
If concrete cures in hot sunny weather or arid climates, then construction can proceed year-round, but evaporation rates increase causing premature drying and cracking
Solution Approach 1:
The patent uses the biobased surfactant to reduce surface tension and slow evaporation rates, converting the harmful effect of hot sunny weather into a manageable condition. The surfactant forms a protective interface that reduces water loss to the environment, enabling construction productivity to maintain in adverse weather conditions without causing drying shrinkage cracks.
4Reliability
If SAP particles are used for internal curing, then self-desiccation is reduced, but they can cause water bleeding and segregation in fresh concrete
Solution Approach 1:
The patent uses biobased surfactant as an intermediary agent between the superabsorbent polymer particles and the cement paste. This surfactant coating on the SAP particles reduces their density difference with the surrounding mixture, preventing water bleeding and segregation while maintaining their internal curing effectiveness. The surfactant acts as a bridge that ensures uniform distribution and stability of the SAP particles throughout the fresh concrete mixture.
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 admixture reduces volumetric shrinkage, decreases stress cracks, and increases compressive strength, while also reducing the carbon footprint by recycling waste materials and minimizing landfill disposal.
Implementation Method 1
superabsorbent polymer (SAP) particles, which are hydrogel-based and capable of absorbing and releasing water during curing of a concrete mixture
Implementation Method 2
The use of dry silica fume and other nanosilica materials in water-based solutions or suspensions is also an established strategy to promote the growth of calcium silicate hydrates (C-S-H) in cement mixtures
Implementation Method 3
C-S-H is the strong cementitious 'glue' that binds together the fine and coarse aggregate in concrete, forming a stronger and denser cement matrix
Data Source
AI summary
Admixtures for concrete, concrete including admixtures, and methods of making admixtures for concrete and making concrete using the admixtures. Such an admixture includes a dry mixture of a silica-based binder and recycled waste material, the latter including at least one of post-consumer waste and/or post-manufacturing waste containing superabsorbent polymer particles and cellulosic particles. The admixture typically is provided in a dry powder form. The recycled waste material may be absorbent hygiene products, such as disposable diapers and/or feminine hygiene products.