Abstract:
In this exploratory study, the effect of super absorbent polymers (SAPs) on the properties of self-compacting pastes (SCPs) incorporated with nano silica (NS) has been investigated. NS was added to cement pastes containing SAPs in varying amounts of 1 %, 2% and 3%. SAPs were found out to be successful in mitigating shrinkage in all formulations, however they were more effective in formulations without super plasticizers (SPs). SAPs reduced 100% shrinkage in formulations without SPs compared with 75% in SCPs. SAPs particles reduced flow, increased air content and also reduced strength slightly due to formation of macro-pores. NS was beneficial in improving the mechanical properties of the SAP modified cement pastes particularly at early ages. SAPs improved the hydration and microstructure of pastes especially in its vicinity while addition of NS resulted in further dense microstructure. The dense 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, due to the enhanced interface. The reduced Ca(OH)2 content in NS modified samples showed increased pozzolanic activity associated with NS in cement pastes
