Preparation and Characterization of Nano-CaCO3/Ceresine Wax Composite Shell Microcapsules Containing E-44 Epoxy Resin for Self-Healing of Cement-Based Materials.

Wei Du,Erwang Li,Runsheng Lin

doi:10.3390/nano12020197

Wei Du, Erwang Li + Show 1 more

Open Access

https://doi.org/10.3390/nano12020197

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Abstract

As an intelligent material, microcapsules can efficiently self-heal internal microcracks and microdefects formed in cement-based materials during service and improve their durability. In this paper, microcapsules of nano-CaCO3/ceresine wax composite shell encapsulated with E-44 epoxy resin were prepared via the melt condensation method. The core content, compactness, particle size distribution, morphologies, chemical structure and micromechanical properties of microcapsules were characterized. The results showed that the encapsulation ability, mechanical properties and compactness of microcapsules were further improved by adding nano-CaCO3 to ceresine wax. The core content, elastic modulus, hardness and weight loss rate (60 days) of nano-CaCO3/ceresine wax composite shell microcapsules (WM2) were 80.6%, 2.02 GPA, 72.54 MPa and 1.6%, respectively. SEM showed that WM2 was regularly spherical with a rough surface and sufficient space inside the microcapsules to store the healing agent. The incorporation of WM2 to mortar can greatly improve the self-healing ability of mortar after pre-damage. After 14 days of self-healing, the compressive strength recovery rate, proportion of harmful pores and chloride ion diffusion coefficient recovery rate increased to 90.1%, 45.54% and 79.8%, respectively. In addition, WM2 also has good self-healing ability for mortar surface cracks, and cracks with initial width of less than 0.35 mm on the mortar surface can completely self-heal within 3 days.

Highlights

The durability of concrete has received much attention in the field of construction materials due to the need for extended service life [1,2]
Microcapsules of nano-CaCO3 /ceresine wax composite shell and E-44 epoxy resin healing agent were prepared via the melt condensation method in order to improve the micromechanical properties and compactness of microcapsules
The addition of nano-CaCO3 reduced the solidification time of the shell and improved the encapsulation ability, which resulted in a higher core content of the microcapsules

Summary

Introduction

The durability of concrete has received much attention in the field of construction materials due to the need for extended service life [1,2]. The extension of cracks can lead to deterioration of cement-based materials, reducing their service life [5]. The “after-the-fact” nature of conventional maintenance suggests that cracks can only be repaired after they have occurred, which increases costs and requires advanced techniques to accurately detect and locate internal cracks [6]. To meet this requirement, selfhealing cement-based materials aimed at automatic crack repair and service life extension have attracted the interest of many researchers [7,8]. The main mechanism of mineral self-healing technology is to mix mineral admixture into cement-based materials, and when there is water infiltration into cracks, the mineral admixture with special composition reacts with the calcium

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Conclusion