Cement powder when mixed with water form a paste which is the essential glue of concrete. The paste is a complex suspensions of micron-size cement particles (ground clinker) and nano-size C-S-H particles (reaction product). They exhibit a colloidal behavior due to interactions between charged particles through an interstitial solution of high ionic strength, giving rise to a macroscopic yield stress, that increases with time at rest. Although there is a density difference of 2.15 g/cm3 between the solute and solvent, these microscopic yield stress helps in keeping a homogeneous paste microstructure. This study is aimed to observe the behaviour of cement paste in parallel plate geometry under oscillatory shear both by rheometry and by local imaging. The cement paste once thoroughly mixed is loaded between serrated parallel plates of Anton Paar rheometer MCR 302 with a gap of 1 mm and the diameter of the plates being 50 mm. A phantom VEO camera is equipped parallel to the gap records images of the paste-air interface at the edge of the plates at a speed of 100 fps. It is assumed that the application of shear to cement paste causes the microstructure to break and given enough time the microstructure will recover and the strength of the paste will be regained to the previous conditions. Although the observation from our studies show that the application of oscillatory pre-shear not only breaks the micro-structure but also creates heterogeneities in the paste causing erroneous results. The findings of our work is backed by performing particle image velocimetry (PIV) with the images obtained and shows formation of local shear bands, sheared with higher local shear rate.