Effective free water diffusion coefficient of cement paste internally cured with superabsorbent polymers

A hybrid model, comprised of analytical and phenomenological models, was developed to quantify the effective free water diffusion coefficient of cement hydration with superabsorbent polymers (SAP) as internal curing. NMR/MRI measurements were used to estimate the water types and distribution, and the cement degree of hydration. Employing reverse engineering, the estimated temporal free water distribution in cement hydration with SAP was reproduced using 1-D finite element transient flow model and a tortuosity model. The computed free water diffusion coefficient and effective diffusion length of cement paste with 0.2% and 0.3% SAP is 5.48 × 10−12 m2/s and 4.46 × 10−12 m2/s, and 0.25 mm and 0.19 mm, respectively. The computed efficacy of SAP dropped by 8% and 27%, for 0.2% and 0.3% SAP content respectively, when accounting for particles agglomeration.