Crack Healing Performance of PVA-Coated Granules Made of Cement, CSA, and Na₂CO₃ in the Cement Matrix.

Yong-Soo Lee,Jae-Suk Ryou

doi:10.3390/ma9070555

Yong-Soo Lee, Jae-Suk Ryou

Open Access

https://doi.org/10.3390/ma9070555

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Abstract

Various self-healing methods for concrete, such as the use of supplementary cementitious materials, adhesive agents, mineral admixtures, and bacteria, have been suggested to date, and each of these has merits and demerits. Among these, however, the use of cementitious materials may be appropriate due to their good healing efficiency, low cost, and compatibility with the cement matrix. In this study, granulation and coating methods were applied to a new cementitious composite material. The self-healing property of these materials was controlled by the polyvinyl alcohol (PVA) coating until cracks were created. Water dissolved the PVA coating after entering through the cracks, and reacted with the healing materials to generate healing products. The self-healing performance was evaluated at various elapsed times through the measurement of the crack widths, visual observation, and examination of the microscopic images. Simultaneously, a water permeability test was performed and the dynamic modulus of elasticity was measured to verify the recovery of the cracks. In addition, the healing products that had been formed in the cracks were analyzed via X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Highlights

Concrete is a widely used construction material because of its numerous advantages, such as its strength, low cost, and ease of manufacture as well as the possibility of constructing structural members with numerous shapes and sizes with it
Granulation/coating methods were applied to healing materials
The healing efficiency of cementitious materials can be maintained via the polyvinyl alcohol (PVA) film thickness until cracks occur, and healing products will be formed because the materials react with the moisture via the crack faces after the moisture dissolves the water-soluble film

Summary

Introduction

Concrete is a widely used construction material because of its numerous advantages, such as its strength, low cost, and ease of manufacture as well as the possibility of constructing structural members with numerous shapes and sizes with it It has some disadvantages, such as its low tensile strength and the appearance of cracks therein. Various types of cracks can arise in plain and reinforced concrete structures, and it is difficult to prevent their occurrence [1,2] They give access to the harmful ions present in the environment, such as chloride, carbon dioxide, oxygen, sulfates, salts, and water, allowing them to enter the concrete and to attack the reinforcing bars and cement paste. The self-repair of the cracks by the concrete has been perceived as a novel solution for reducing the life cycle cost (LCC)

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Discussion

Conclusion