Zero External Water Concrete Using Superabsorbent Polymer (SAP) as Internal Curing Agent

Abstract

Self-curing concrete has emerged as an effective solution for minimizing water loss and improving hydration, especially in regions facing water scarcity and inadequate curing practices. This study investigates the performance of self-curing concrete incorporating Super Absorbent Polymer (SAP), MYK Arment ArmixEmmecrete PC-10, and Recron 3S fibers to enhance mechanical and durability properties without continuous external curing. The experimental program used M30 and M25 grade concrete with SAP dosage of 0.2% by weight of cement, constant PC-10 (0.5%), and Recron 3S fiber at 1.25% and 2.25% volume fractions. Fresh concrete properties were evaluated via slump and flow table tests; hardened properties through compressive strength, split tensile strength at 7, 14, and 28 days. Microstructural investigations using XRD confirmed enhanced hydration and denser C–S–H gel in SAP-modified mixes. Results indicate that the combination of SAP and PC-10 significantly improves internal moisture retention, leading to compressive strength within 3% of the conventionally cured control, while Recron 3S fibers at 1.25% improved split tensile strength by approximately 14.5% at 28 days in M30 grade.

Introduction

This study investigates self-curing concrete as an alternative to conventional water curing, which is often difficult due to water scarcity, labor constraints, and inaccessible construction sites. Self-curing concrete uses Super Absorbent Polymers (SAP) that absorb and gradually release water within the concrete, ensuring continuous cement hydration, reducing shrinkage, minimizing cracking, and improving durability. The research examines M25 and M30 grade concrete incorporating SAP, PC-10 polycarboxylate-based superplasticizer, and Recron 3S synthetic fibers.

The objectives were to develop self-curing concrete, reduce dependence on external curing, determine the optimum SAP dosage, compare its performance with conventional concrete, and analyze microstructural properties through XRD and SEM techniques. Materials used included OPC 53 grade cement, river sand, crushed granite aggregates, SAP (0.1–0.3%), PC-10 superplasticizer (0.5–0.8%), and Recron 3S fibers (1.25% and 2.25%).

Experimental testing involved preparing M25 and M30 concrete mixes under self-curing conditions and evaluating their workability, compressive strength, split tensile strength, and microstructural characteristics at 7, 14, and 28 days. Slump and flow table tests confirmed acceptable workability for reinforced concrete applications.

Results showed that conventional concrete achieved the highest compressive strength in both M25 and M30 grades. However, self-curing concrete with 0.2% SAP, 0.8% PC-10, and 1.25% Recron 3S fibers achieved compressive strengths very close to the control mix, demonstrating effective internal curing. Increasing fiber content to 2.25% reduced compressive strength because of lower workability, poor fiber distribution, and increased air voids.

In split tensile strength tests, the 1.25% fiber self-curing mix outperformed conventional concrete, particularly in M30 grade, achieving about 14.5% higher tensile strength at 28 days due to the crack-bridging effect of fibers. Excessive fiber content again resulted in lower performance.

XRD analysis confirmed the presence of both crystalline hydration products and amorphous polymer phases, indicating successful SAP incorporation. The findings suggest that SAP-based self-curing concrete can maintain adequate hydration, improve tensile performance, reduce shrinkage and cracking, and provide a practical solution for construction in water-scarce or difficult curing environments. The optimum performance was achieved with 0.2% SAP and 1.25% Recron 3S fiber content, making self-curing concrete a sustainable and efficient alternative to conventional curing methods.

Conclusion

The following conclusions are drawn from this study: 1) The SAP-based internal curing system effectively replaced external water curing by maintaining internal relative humidity and supporting continuous cement hydration throughout the 28-day period. 2) The 0.2% SAP dosage combined with 0.5% PC-10 was identified as the optimum blend, achieving compressive strengths of 29.77 MPa (M30) and 23.84 MPa (M25) at 28 days — within 3% of the conventionally cured control mix. 3) Recron 3S fibre at 1.25% volume fraction improved split tensile strength at 28 days by approximately 14.5% in M30 grade, confirming the fibre bridging effect on crack arrest and tensile toughness. 4) Increasing fibre content to 2.25% caused a measurable decline in compressive strength and workability due to fibre clustering, increased air void entrapment, and non-uniform distribution. 5) Self-curing concrete using SAP and PC-10 is a practical and effective solution for construction in water-scarce regions, precast applications, high-rise structures, and wherever continuous external curing is difficult to maintain.

References

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Copyright

Copyright © 2026 Ankit ., Sharath Chouka, Amaresh Patil. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.