Experimental Study of Sodium Polyacrylate on Fiber Reinforced Self Curing Concrete

Abstract

In order to get the necessary properties of concrete, the early stages of the curing process need maintaining a sufficient moisture content and temperature. But effective curing of concrete is not always possible in many situations. An attempt has been made to produce internally cured concrete using sodium polyacrylate, as super absorbent polymer. An experiment was conducted using M25 grade concrete with sodium polyacrylate at 0.1%, 0.3%, and 0.5% by weight of cement, respectively. Sodium polyacrylate was chosen because of its ability to absorb and gradually release water. Concrete is commonly used in construction due to its compressive strength, however it has considerable weaknesses in tensile strength. To address these concerns, an attempt has been made to improve the tensile strength of concrete by incorporating fibers. This experiment aims to evaluate the impact of super absorbent polymers (SAPs) on the mechanical properties of coconut and polypropylene fiber-reinforced concrete. The mechanical properties of different concrete mix with varying amounts of SAPs, polypropylene fibers, and coconut fibers were evaluated. Concrete cubes and cylinders were cast and tested for seven days and twenty-eight days, respectively According to the experiment results, when SAP was used in concrete with different amounts of coconut and polypropylene fibers, the compressive and tensile strength of the concrete increased.

Introduction

I. INTRODUCTION

This document is a template.  For questions on paper guidelines, please contact us via e-mail. Concrete is a brittle substance with low tensile and high compressive strength. Fibers are being added into concrete to help it overcome these drawbacks. One of the main reasons for utilizing fibers in concrete is to improve its tensile and flexural strength. Fiber-reinforced concrete is a composite material made of concrete that has discrete, evenly spaced, or discontinuous fibers added to it. Concrete is simply strong in compression but weak in tension.

As concrete dries and cures, it experiences volumetric changes that may cause shrinkage and the development of cracks. Fibers serve to regulate and minimize these cracks by providing additional support that restricts the expansion and contraction of the concrete. This is particularly helpful in reducing plastic shrinkage cracks that arise when the concrete is still in its plastic condition and drying shrinkage cracks that arise as the concrete hardens. Another important advantage of fiber-reinforced concrete is its greater toughness and impact resistance. Concrete that contains natural fibers, such coconut fibers, has better mechanical qualities and supports environmental sustainability. Natural fibers are a more sustainable option than synthetic ones because they are biodegradable, renewable, and frequently available locally. The tensile strength of concrete is strongly increased by adding fibers, whether they come from manmade materials or natural sources like coconut husk. These fibers, as reinforcement, disperse stress uniformly and prevent cracks from forming.

In this experiment, we produced fiber-reinforced concrete using coconut and polypropylene fibers to reduce the formation of micro-cracks that may occur during the curing process. It is essential to maintain proper moisture and temperature throughout the early curing phases in order to obtain the necessary characteristics. For optimal strength development, concrete must be maintained wet during the curing process. There are several ways to maintain moisture on the surface of the concrete, including pounding, spraying, and sealing the surface with a barrier made of curing compound to stop moisture loss. But in many cases, effective cure isn't always possible. Therefore, employing chemicals that self-cure will be the best option. Self-curing chemicals help to lower evaporation, which enhances concrete's water retention.

This experiment used sodium polyacrylate, a super absorbent polymer (SAP) known for its ability to absorb and hold large amounts of water. Sodium polyacrylate and other cross-linked polymers are used to make SAPs, which are commonly utilized in hygiene, agriculture, and packaging products. SAPs improve internal curing in concrete by absorbing excess water while mixing and releasing it gradually.

This reduces autogenous shrinkage. SAPs also improve hydration by gradually releasing water, so cement particles are thoroughly hydrated. The concrete's strengthened by this ongoing hydration. SAPs also decrease the chance of concrete cracking. By incorporating SAPs into concrete, performance problems can be addressed, and environmental sustainability in buildings can be improved.

II. AIM OF EXPERIMENT

1. To find the optimal dose of superabsorbent polymer (SAP) utilized in self-curing concrete.
2. To find the optimal dose of coconut and polypropylene fibers in fiber-reinforced self-curing concrete.
3. To determine the compressive strength and split tensile strength of controlled concrete, self-cured concrete, and fiber-reinforced self-cured concrete.

III. MATERIALS

The basic components of a concrete mix were cement, coarse and fine aggregates, water, chemical additives and mineral admixtures. Several types of reinforcing fibers could be utilized in construction -related concrete. In this experiment, 10% of the cement was replaced with flyash, and the concrete was reinforced with different quantities of polypropylene and coconut fibers. Sodium polyacrylate was utilized as a self curing agent.

1) Cement: OPC43 grade cement was utilized throughout the experimental program, conforming to IS: 8112 – 1989 specifications. Multiple tests were done on the cement, which indicates a specific gravity of 3.12, fineness of 8.56%, and a consistency of 31%.

2) Flyash: Fly ash is a byproduct of coal-fired power plants that interacts with lime to produce cementitious compounds. In this experiment, class C fly ash was employed. Flyash had a 2.40 specific gravity, according to test.

3) Sand: River sand, which is readily available in the area, was utilized as fine aggregate in the experimental program. Its specific gravity was 2.76 and its fineness modulus was 2.63. According to IS-383-1970, river sand falls under zone II.

4) Coarse Aggregate: The aggregate particles retained on a 4.75 mm IS sieve are referred to as coarse aggregate. Up to a maximum size of 20 mm, locally available coarse aggregate was used in the experimental program. Specific gravity of the coarse aggregate was measured to be 2.82, and its fineness modulus was found to be 4.07, confirming to IS 393-1970.

5) Water: The water used to create concrete shouldn't contain oil, alkalis, acids, or any other harmful impurities. In the lab, drinking water was used to produce concrete and allow it to cure.

6) Sodium Polyacrylate: The super absorbent polymer used in this experiment was sodium polyacrylate. Super absorbent polymers (SAP) are a subclass of polymeric materials. SAPs, as employed in this experiment, are non-corrosive, non-toxic materials that can absorb water several times their own weight. which had bulk density of 0.85 and density of 1.08.

Conclusion

1) Self-curing concrete with 0.3% SAP had a higher water retention rate than self-curing concrete with 0.1% and 0.5% SAP, respectively. 2) It has been found that the optimum SAP dose produces better outcomes than SAP excessive amounts. Concrete may become weakened by excessive sap consumption. 3) It has been found that sodium polyacrylate is a more beneficial material for producing strong, internally cured concrete. Due to its ability to cure without drying out, self-cured concrete helps conserve water. A good material to utilize in areas with water limitations and curing-related issues is self-curing concrete. 4) For M25 grade concrete, the optimal SAP dosage has been found to be 0.3% in order to optimize the concrete\'s strength. With the addition of SAP, the compressive and split tensile strengths increased significantly. 5) The addition of polypropylene and coconut fibers improves the compressive strength and split tensile strength of fiber reinforced self curing concrete. In this experiment, the optimum dosage was found to be 1% for coconut fiber and 1.5% for polypropylene fiber. 6) Concrete reinforced with polypropylene fibers showed better results compared to concrete reinforced with coconut fibers. Additionally, the use of coconut fibers was found to minimize the weight of the fiber-reinforced concrete.

References

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Copyright

Copyright © 2024 Nirdesh Vaidya, Pukhraj Sahu. 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.