Modeling SAOS Yield Stress of Cement Suspensions: Microstructure-Based Computational Approach

Area of Science:

• Materials Science
• Rheology
• Colloid Science

Background:

• Yield stress in cement suspensions arises from particle network formation due to attractive forces.
• Existing models like YODEL, based on van der Waals forces, are insufficient for reactive cementitious systems.
• Small Amplitude Oscillatory Shear (SAOS) tests probe the linear viscoelastic limit where yield stress initiates.

Purpose of the Study:

• To comparatively simulate the yield stress of cement suspensions using two static yield stress models: YODEL and the novel BreakPro model.
• To investigate the fragility of the rigid percolated structure in cement suspensions by estimating inter-particle forces.
• To assess the suitability of microstructural-based models for describing yield stress in reactive cementitious materials.

Main Methods:

• Comparative simulation of cement suspension yield stress using YODEL and BreakPro models.
• Application of oscillatory rheological tests with SAOS to induce and measure yield stress.
• Calibration of model parameters using measured yield stresses from high-sensitivity rheometry.
• Inverse estimation of inter-particle forces and percolation thresholds.

Main Results:

• Estimated inter-particle forces were significantly higher than van der Waals forces: 5.57 times for BreakPro and 1.43 times for YODEL.
• The BreakPro model yielded a higher percolation threshold (37%) compared to the YODEL model (21%).
• BreakPro's modeling assumptions proved more suitable for describing yield stress at the SAOS critical strain in cement suspensions.

Conclusions:

• The BreakPro model, incorporating inter-particle bond breaking probability, provides a more accurate description of yield stress in cement suspensions under SAOS conditions.
• Cementitious suspensions exhibit significantly stronger inter-particle attractive forces than predicted by van der Waals interactions alone.
• The study introduces a valuable mathematical tool for analyzing the structural fragility of cementitious materials.