The Basic Mechanical Properties and Shrinkage Properties of Recycled Micropowder UHPC

Area of Science:

• Construction Materials Science
• Sustainable Engineering
• Concrete Technology

Background:

• Construction waste recycling is crucial for sustainability.
• Utilizing waste clay brick powder (RBP) as a partial cement replacement in concrete offers a viable recycling pathway.
• Ultra-high-performance concrete (UHPC) requires investigation into the properties of recycled materials.

Purpose of the Study:

• To evaluate the physical, mechanical, and volume stability of recycled micropowder ultra-high-performance concrete (UHPC).
• To determine the optimal replacement rates of RBP for UHPC preparation.
• To assess the impact of RBP on autogenous and drying shrinkage of UHPC.

Main Methods:

• UHPC specimens were prepared with RBP replacing cement at rates of 10%, 20%, 30%, 40%, and 50%.
• Compressive strength, flexural strength, and splitting tensile strength were measured.
• Autogenous and drying shrinkage were analyzed, and prediction models were developed.

Main Results:

• Mechanical strengths (compressive, flexural, tensile) initially increased with RBP content, peaking at 10% replacement.
• Autogenous shrinkage consistently decreased with increasing RBP rates.
• Drying shrinkage was minimized at 30% RBP replacement, showing a 49.7% reduction compared to the control.

Conclusions:

• Activated RBP can enhance UHPC mechanical properties and significantly reduce both autogenous and drying shrinkage.
• A 10% RBP replacement optimizes mechanical strength, while 30% is ideal for minimizing drying shrinkage.
• Developed shrinkage prediction models accurately reflect experimental data for RBP-UHPC.