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

Abstract

Two static yield stress models, one known as YODEL and the newly proposed BreakPro, based on inter-particle bond breaking probability, were employed to comparatively simulate the yield stress of cement suspensions, induced by oscillatory rheological tests with small amplitude oscillatory shear (SAOS). This yield stress occurs at a critical strain in the order of 0.01%, and is commonly attributed to the limit of the linear viscoelastic domain, where attractive forces bridge the cement particles and form a flocculated particle network. YODEL is based on van der Waals (vdW) interaction forces to describe the yield stress for flow onset at a critical strain of a few percent, developed for simple non-reactive particulate suspensions. However, due to the high pH and reactivity of cementitious suspensions, their particle interaction forces are much higher than vdW. Therefore, until now, the YODEL adaptations to cementitious suspensions did not explicitly consider the microstructural-based salient feature of the original model, but used it as an implicit fitting parameter to scale the average attractive force. In this paper, the force is inversely estimated using the full power of the two microstructural-based models, presenting a new mathematical tool for investigating the fragility of the rigid percolated structure of cement suspensions. The model parameters were calibrated on measured yield stresses obtained by SAOS measurements in a high-sensitivity rheometer. The estimated forces were found to be 5.57 (BreakPro) and 1.43 (YODEL) times higher than typical van der Waals forces. The YODEL percolation threshold of 21% turned out to be significantly lower than the one found by the BreakPro model (37%). This indicated that BreakPro modeling assumptions are better suited for the description of yield stress at SAOS critical strain than the YODEL model.

Effect of Solid Volume Fraction on the Magnetorheological Response of Nano-Fe3O4 Incorporated Cementitious Paste

“…When the solid volume fraction is higher than 0.326, however, the critical strain almost remains unchanged. Similar phenomena were also observed in Yuan et al (2017), Ukrainczyk et al (2020), and Mostafa and Yahia (2016), but no detailed explanation was provided. The critical strain from the oscillatory strain-sweep test corresponds to the breakage of early hydration products between cement particles (Roussel et al 2012;Huang et al 2019;Jiao et al 2021a).…”

“…Note that the formation of more hydration products does not necessarily mean a higher stiffness or more solid-like properties of the suspension, as a higher w=c system requires more products to develop a percolating structure due to the larger solid-to-solid spacing (Zhang et al 2010). Furthermore, the C-S-H gel in a cement paste with a higher particle volume fraction possibly becomes more fragile (Ukrainczyk et al 2020). Consequently, the deformation capacity of the bridges of early hydration products increases with the decrease of solid volume fraction, and thus a slightly higher critical strain is observed for the cementitious pastes with lower solid volume fraction.…”

Multidisciplinary approach for the prediction of cement paste rheological properties: physical analysis, experimental rheology and microstructural modelling

“…𝜏𝜏 𝑦𝑦 therefore is lower than 𝜏𝜏 0,𝐻𝐻−𝐵𝐵 . Further chemical and physical relation can be found in [10], application of the comparison between 𝜏𝜏 𝑦𝑦 and numerical modelling by Ukrainczyk et al in [11]. To investigate structural buildup or agglomeration processes, the static oscillatory buildup test was performed at a strain lower than 𝛾𝛾 𝑙𝑙 and the evolution of 𝐺𝐺′ and 𝐺𝐺′′ was observed for a structural buildup time of 20 min.…”

C3A Variation in Synthetic Model Cements ‐ Influence on Rheology and Reactivity

“…For all experiments, two serrated plates with a diameter of 25 mm (PP25/P2) were used at a measuring gap of 1 mm. The measurement profile was based on a strain sweep (strain γ increased from 10 -4 to 10 1 %) in oscillatory mode at a constant frequency (ω = 10 rad/s) [16].…”