Multivariable models to forecast the mechanical properties of polymerized cement paste

In this study, the impact of two types of polymer on the stress–strain behavior, elastic modulus and toughness of cement paste, were investigated and quantified. The cement paste was modified with two types of polymer up to 0.06% (based on the dry weight of cement), and the samples were cured at different curing times (1, 3, 7, and 28 days) before testing. Polymers increased cement flowability by 7%–26% and lowered the water/cement ratio (w/c) by 12%–43%, based on the types of polymer and polymer content. The nonlinear Vipulanandan p-q model was used to predict the stress–strain behavior of modified cement, and the results were compared to the β model. The elastic modulus (E) at different strain levels and total toughness (TT) of the modified cement was determined by differentiating and integrating the Vipulanandan p-q model. When 0.06% polymers were added to cement paste, the compressive strength increased by 107–257%. During the early curing age, the cement modified with polymer was able to withstand large deformations that mean increase the ductility of the materials, but with increasing curing, the cement modified with polymers become brittle and the strain at failure reduced. Adding polymers to the cement paste creates an amorphous gel that fills the spaces between cement particles with working fibers net or meshes covering the cement particles, which cause a reduction in the voids, porosity and increasing the density of the cement, subsequently the mechanical properties significantly increased.