Optimization of Mix Proportions for Type IV Cement-Based Grouting Materials Using Orthogonal Experimental Design

Area of Science:

• Materials Science and Engineering
• Civil Engineering
• Construction Materials

Background:

• Grouting materials are vital for infrastructure repair and construction.
• Optimizing cement-based grouts requires understanding the interplay of various admixtures.
• Type IV cement grouts present unique challenges in balancing fluidity and strength.

Purpose of the Study:

• To systematically investigate the effects of water-to-binder ratio, total binder content, silica fume, and fly ash on Type IV cement-based grouting materials.
• To determine the optimal mix proportion for enhanced workability and compressive strength.
• To elucidate the microstructural and hydration mechanisms influenced by these admixtures.

Main Methods:

• An L16(4^4) orthogonal experimental design was employed.
• Evaluated initial and 30 min slump flow, and 1, 3, and 28-day compressive strength.
• Utilized XRD, SEM, and hydration heat tests for microstructural and mechanistic analysis.

Main Results:

• Silica fume content significantly impacts initial slump flow.
• Water-to-binder ratio is key for 30 min slump flow and early-age strength.
• Total binder content is critical for 28-day compressive strength.
• Fly ash improves fluidity and later-age strength, while silica fume enhances early strength but reduces fluidity.
• An optimal substitution range exists for fly ash and silica fume.

Conclusions:

• The optimal mix proportion (A3B2C4D2) achieved a balance of workability and strength.
• This formulation included a water-to-binder ratio of 0.31, 15% fly ash, 690 kg/m3 total binder, and 8.5% silica fume.
• Admixtures optimize hydration and microstructure densification for improved performance.