In micro particle suspensions there are a variety of forces acting between the particles. In order to accurately simulate these suspensions, it is necessary to consider not only the contact forces between the particles and the fluid (such as drag and lubrication forces), but also the normal and tangential contact forces between the particles themselves. Current simulation methods, such as coupled CFD-DEM simulations, typically do not account for all of these forces, which has prevented a fully realistic representation of the rheological behavior of the suspensions. To address this issue, researchers investigated the effect of different forces on the rheology of the suspensions. The authors found that a contact model, a static friction model, a rolling friction model, a drag model, a rotational drag model and a lubrication model are all required to accurately describe the rheological properties of micro particle suspensions. Contact and static friction models are needed to account for direct particle contact and have been well studied. Rolling friction is critical to represent the non-spherical nature of the particles [1]. Drag forces accelerate and decelerate the particles, while rotational drag forces keep them rotating. Although the rotational drag force is typically only considered in resolved simulations, it should not be overlooked for an accurate description of viscosity [2]. Lubrication forces account for the displacement of fluid between particles and help to dissipate energy within the suspension [3]. In addition, a combination of electrostatic, steric and van-der-walls forces are required to account for colloidal suspensions [4]. For reactive suspensions such as cement pastes, interparticle bonds must be added. Overall, our simulations with these forces show good agreement with both analytical models and experimental data on micro particle suspensions over a broad range of volume fractions.