Self-Sealing Process Evaluation Method Using Ultrasound Technique in Cement Composites with Mineral Additives

Area of Science:

• Materials Science
• Civil Engineering
• Concrete Technology

Background:

• Self-sealing in cement composites recovers material integrity through chemical and microstructural changes.
• Assessing self-sealing effects non-destructively is challenging due to confounding factors like hydration and sample variability.
• Existing methods struggle to isolate and quantify self-sealing phenomena accurately over time and across different material properties.

Purpose of the Study:

• To develop and validate a novel ultrasonic pulse velocity (UPV) technique for quantifying self-sealing in cement-based materials.
• To differentiate self-sealing effects from ongoing binder hydration processes.
• To propose new parameters for the quantitative characterization of the self-sealing process.

Main Methods:

• Application of an ultrasonic pulse velocity (UPV) technique with a refined data processing procedure.
• Development of specific sample preparation and testing conditions to minimize moisture content influence on UPV measurements.
• Evaluation using cement mortars with induced cracks (0-750 µm) modified with siliceous fly ash, cured for 152 days.

Main Results:

• The UPV method successfully quantified material changes related to self-sealing, excluding hydration effects.
• Effective crack filling due to autogenous self-sealing ranged from 33% to 57% in the tested mortars.
• Microstructural analysis indicated that the density of newly formed products, in addition to volume, significantly impacts ultrasonic measurements of self-sealing.

Conclusions:

• The proposed ultrasonic method offers a reliable approach for investigating and quantifying the self-sealing performance of cement composites.
• The study provides new insights into the factors influencing ultrasonic measurements of self-sealing, including crack width and product density.
• This research contributes to the development of more durable and resilient cement-based materials through enhanced self-healing capabilities.