Optimization of superplasticiser and viscosity modifying agent in self compacting mortar

This paper investigated the use of mini slump cone test along with the graduated glass plate to obtain the optimization of Superplasticiser (SP) and Viscosity Modifying Agent (VMA) in self compacting mortar (SCM). The SCM mixes had 35% replacement of cement with class F fly ash and water/cementitious ratios by weight (w/cm) 0.32 and 0.36. It is observed that for the same cementitious proportions, the optimum dosage of SP was the same for the mixes having w/cm 0.32 and 0.36. Mortar mixes with w/cm 0.36 showed an increase in the rate of flow i.e., lower viscosity at each level of SP dosage as compared to that of mixes with w/cm 0.32. It is also observed that minimum dosage of VMA was required to use in the mortar mixes having w/cm 0.36 in order to arrest the bleeding. Whereas, the use of VMA dosage was not required to use in the mortar mixes having w/cm 0.32 as no bleeding was observed at the optimum dosage of SP. Practically, it is seen that mini slump cone test is the best choice for SCM tests to evaluate the mortar spread and its viscosity (T20). Also, it is seen that percentage of sand in mortar doesn t affect the optimum dosage of SP (saturation point) when the cementitious proportions are kept the same.