Properties enhancement of super absorbent polymer (SAP) incorporated self-compacting cement pastes modified by nano silica (NS) addition

In this exploratory study, the effects of nano silica (NS) on the properties of self-compacting pastes (SCPs) incorporated with superabsorbent polymer (SAP) have been investigated. NS was added to cement pastes, containing SAP, in varying amounts of 1%, 2% and 3%. SAP were found out to be successful in mitigating shrinkage in all formulations; however they were more effective in mixes without super-plasticizers (SPs). SAP particles reduced the fluidity, increased the air content and also reduced strength slightly due to the formation of macro-pores. NS was beneficial in improving the hydration attributes by increasing the mechanical strength and refining the microstructure. The denser microstructure of the NS modified pastes compensated for the macro pore formation associated with SAP incorporation, leading to strength increase. With NS, there was better bonding of the SAP particles in the matrix. The reduced Ca(OH)2 content in NS modified samples showed increased pozzolanic activity associated with NS in cement pastes.