International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 05 | May 2025
p-ISSN: 2395-0072
www.irjet.net
Self-Healing Concrete Integrated with CO₂-Absorbing Techniques Gargi Nawale1 1High School student, Blossom Public School, Maharashtra, India
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Abstract - Highways often crack due to heavy vehicles and
combine with free Ca²⁺ ions in the cement matrix to form calcium carbonate (CaCO₃) — a solid mineral that seals cracks.
heat. Fixing them again and again costs a lot and creates more pollution, especially from cement. This study talks about a smart type of concrete that heals itself using bacteria (Bacillus pseudofirmus) and natural zeolite, a mineral that helps trap carbon dioxide. The bacteria close the cracks by forming calcium carbonate, while zeolite catches extra CO₂ from the air. We tested it in Indian weather and found that it healed cracks on its own, made the concrete stronger, and even reduced carbon dioxide. This eco-friendly material can help make our roads and infrastructure last longer and reduce pollution.
The key biochemical reactions involved are: CO(NH₂)₂ + 2H₂O → 2NH₄⁺ + CO₃²⁻ Ca²⁺ + CO₃²⁻ → CaCO₃↓ Zeolites are made up of tiny building blocks called SiO₄ and AlO₄ that join together to form a 3D network, like a sponge . When aluminum (Al³⁺) replaces some of the silicon (Si´⁺), it creates negative charges in the structure. These charges attract and hold on to positive ions like sodium (Na⁺) and calcium(Ca²⁺), as well as water. This special structure makes zeolites great at holding nutrients and capturing carbon dioxide (CO₂). Zeolite’s with a porous crystalline structure enhance the performance of this system in two ways:
Key Words: Self-healing concrete, Zeolite, CO2 absorption Bacillus pseudofirmus 1. INTRODUCTION India’s 6.6 million km road network is under constant stress from heavy traffic, thermal cycles, and poor drainage, leading to the frequent formation of cracks in concrete. These cracks not only compromise the durability of the roads but also result in costly repairs. At the same time, the construction sector, particularly cement production, contributes significantly to CO₂ emissions. While traditional methods of repair exist, I thought about combining bio-based self-healing techniques with CO₂trapping materials to create a more sustainable solution. The idea involves integrating Bacillus pseudofirmus, a bacteria that uses microbial induced calcium carbonate precipitation (MICP) to seal microcracks, and natural zeolite, a mineral that helps trap carbon dioxide. This combination offers the potential for enhanced durability, reduced maintenance, and an eco-friendly approach by facilitating CO₂ capture. After performing a few experiments, I estimated the effectiveness of this hybrid material, which showed promising results in both crack healing and carbon dioxide reduction, offering a new way forward for improving highway infrastructure in India.
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CO₂ Adsorption: Zeolite’s high surface area and cation-exchange capacity allow it to trap atmospheric CO₂, increasing the concentration of dissolved carbon dioxide near the crack site and fueling more mineralization by the bacteria.
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Microbial Support: The porous network of zeolite retains moisture and nutrients, helping bacteria survive longer in the alkaline, dry concrete environment. The diagram give below shows the structure of zeolite.
1.1 Chemistry Behind Self-Healing Concrete with Zeolite and Microorganisms Fig -1: Structure of Zeolite
The core chemical process enabling self-healing in this concrete is Microbially Induced Calcium Carbonate Precipitation (MICP). When cracks form, moisture and CO₂ enter, activating inactive Bacillus pseudofirmus spores embedded in the concrete. These bacteria metabolize urea and calcium lactate, producing carbonate ions (CO₃²⁻) that
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2. Material Integration and implementation Self-healing bio-concrete with zeolite is designed to function passively in real-world infrastructure, especially in India's
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