Vipulanandan Constitutive Models to Predict the Rheological Properties and Stress–Strain Behavior of Cement Grouts Modified with Metakaolin

In this study, the effects of metakaolin clay (MK) on the rheological properties, setting time, compressive strength, and toughness of cement grouts with water-cement ratios (w/c) of 0.6 and 1.0 were investigated. Based on the information in the literature, the amount of MK used in various mix designs varied up to 10 % by the weight of cement. The compressive stress–strain behavior of cement grout modified with MK was investigated up to 90 days of curing. The addition of 10 % of MK increased the apparent viscosity of the cement grout from 20 cP to 62 cP and from 13 cP to 44 cP with w/c ratios of 0.6 and 1, respectively. Setting time of cement grout mixes with a w/c ratio of 1.0 had longer initial and final setting times than the grout mixes with a w/c ratio of 0.6. The addition of 10 % MK increased the compressive strength of the cement grouts with w/c ratios of 0.6 and 1 from 8 MPa (1,175 psi) to 30.1 MPa (4,366 psi) and from 2.4 MPa (348 psi) to 17.8 MPa (2,582 psi) after 90 days of curing, respectively. The addition of 10 % MK increased the toughness of the cement grouts with w/c ratios of 0.6 and 1 from 1.42 J·m⁻³ to 2.27 J·m⁻³ and from 0.94 J·m⁻³ to 1.38 J·m⁻³ after 90 days of curing, respectively. The Vipulanandan p–q model was used to predict the changes in stress-stain behavior with curing time. The Vipulanandan rheological model also has a limit on the shear stress were as the other model did not have a limit. Based on the Vipulanandan rheological model, the maximum shear stresses produced by the portland cement grouts with w/c ratios of 0.6 and 1 with 0 MK were 58 Pa and 33 Pa, respectively. The addition of 10 % MK to the Portland cement (PC) grouts increased the maximum shear stresses by 155 % and 136 % for w/c ratios of 0.6 and 1, respectively.