Buildability is the printed layer's ability to withstand self-weight and the load from subsequent layers printed on it without deviating from the design due to deformation. The first objective of the present study is to understand the fresh state rheological properties as well as early age mechanical properties influencing the layer deformation while printing. The study further seeks to establish the squeeze flow test (based on the concept of compressive rheology) as a method to predict the deformation of layers during printing. A model is developed to predict the deformation of the layers. The mix behaves like a combination of linear elastic solid and power-law fluid. The squeeze flow test leads to the determination of four material classification parameters: elongational viscosity, compressive yield stress, shear modulus, and power-law consistency by compressing an axisymmetrical cylinder between two lubricated plates at different compression rates using a universal testing machine. The test was performed over 5 hours to capture the effect of structuration on compressive rheology. A step loading test was performed at different compression rates, mimicking the real-time printing to understand the impact of periodic load on layers. The creep loading test was also performed with constant loads to determine the layer behaviour under the weight of layers printed over it when the surcharge load does not increase. The addition of alkali-free aluminium sulphate based accelerating admixture on these properties was studied further to determine the optimum accelerator dosage to be mixed with the pumped concrete at the nozzle. Print trials were performed to validate the observations from lab-scale studies. The second objective of the study is to understand the microstructural developments critical for better buildability of the structures. The effect of accelerating admixture on the microstructure and its significance on macro-scale behaviour was established. XRD analysis was carried out on samples collected at 30, 90, 300 minutes and 24 hours from initiation of mixing to understand the evolution of phases. The effect of adding an accelerator on the surface morphology of phases in the initial hours was observed on samples using a high-resolution scanning electron microscope.