Description:TECHNICAL FIELD
The invention relates to the field of construction materials, specifically to concrete technology. It focuses on improving the service life and durability of concrete structures by incorporating hydrogel-based internal curing systems to mitigate autogenous shrinkage, improve hydration, and reduce early-age cracking.
Background of the Invention:
Concrete is the most widely used construction material in the world, but its long-term performance is often hindered by insufficient curing, especially in high-performance and low water-cement ratio concretes. Traditional external curing methods often fail to provide adequate internal moisture, leading to autogenous shrinkage and micro-cracking that compromise durability and service life.
To address these limitations, internal curing methods have been proposed. Superabsorbent polymers (SAPs), commonly referred to as hydrogels, are promising internal curing agents due to their capacity to absorb and retain large amounts of water and then gradually release it during the hydration process.
However, challenges such as dosage control, dispersion, compatibility with cementitious materials, and long-term stability of hydrogels in the concrete matrix remain to be addressed.
Summary of the Invention:
This invention provides a novel method for enhancing the service life of concrete by incorporating a specially formulated hydrogel as an internal curing agent. The hydrogel is designed to absorb mixing water during the batching process and release it gradually to sustain cement hydration internally, even in the absence of external curing.
The invention describes:
• The synthesis or selection of hydrogel materials with high swelling capacity and stability in the alkaline environment of concrete.
• The optimized proportioning of hydrogel (0.1–0.5% by weight of cement) to ensure effective water retention and minimal negative impact on workability.
• The improvement in mechanical properties, reduction in autogenous shrinkage, enhancement in microstructure (as seen in SEM), and durability properties such as lower permeability and reduced chloride ingress.
Detailed Description of the Invention:
1. Material Composition:
o Hydrogel: Crosslinked polymer (e.g., polyacrylate-based SAP) with high water absorption capacity.
o Cement: Ordinary Portland Cement (OPC) or blended cement.
o Aggregates: Fine and coarse aggregates conforming to IS standards.
o Water-to-cement ratio: Typically between 0.3–0.45.
2. Method of Incorporation:
o The dry hydrogel powder is mixed with cement and aggregates before the addition of water.
o Upon addition of mixing water, the hydrogel absorbs excess water and swells.
o During the hydration process, the absorbed water is gradually released, sustaining internal curing.
3. Advantages:
o Reduction in autogenous shrinkage by up to 60%.
o Increase in compressive strength by 5–10% after 28 days.
o Decrease in permeability by over 25%.
o Enhanced resistance to drying shrinkage and thermal cracking.
o Improved microstructure due to continued hydration and densification of the C-S-H gel.
, Claims:Claims:
Claim1:
A concrete composition comprising cement, fine and coarse aggregates, water, and hydrogel in the range of 0.1% to 0.5% by weight of cement, wherein the hydrogel acts as an internal curing agent by absorbing mixing water and gradually releasing it to sustain cement hydration, thereby improving the service life of the concrete.
Claim 2:
The method of enhancing service life of concrete, comprising incorporating a superabsorbent polymer-based hydrogel during batching, wherein the hydrogel provides internal curing by mitigating autogenous shrinkage and reducing early-age micro-cracks, resulting in improved long-term durability and mechanical performance.
Claim 3:
A method for producing durable concrete structures comprising the steps of mixing cement, aggregates, water, and hydrogel, wherein the hydrogel maintains internal moisture availability throughout the curing process, leading to a denser microstructure, lower permeability, and enhanced resistance to chloride ingress and thermal cracking.