Studies On The Action Mechanism Between SCA Modified Granite Aggregates And Cement Pastes

Mechanical testing shows that interfacial bond strength between SCA-soaked granite andcement paste is extremely improved. In order to provide technology support for the practicalapplication of SCA modified concrete, a three-factor-five-level orthogonal design was set toinvestigate the influence of SCA concentration,ratio of ethanol / water,dipping time and theinteractions among the factors on concrete compressive strength with SCA modified graniteaggregates. The result shows that a combination of ethanol / water 4:1, dipping 1 min and SCAconcentration of 0.5%～1% yields an optimum solution.FTIR and XPS experiment has already identified that strong bonds can be formed betweenSCA and granite surface, but the action mechanism between SCA modified granite surface andcement pastes is still unknown. For deeply investigating the modifying mechanism of theinterfacial bond strength between SCA-soaked granite and cement paste, a new experimentalmethod to simulate crystallization of cement hydration products on aggregates surface wasdeveloped. The crystal morphology of the cement hydration products is observed by SEM; thecontents and orientation of Ca(OH)₂ on aggregate surface are observed by XRD; the chemicalshifts of each crystal cement hydration products element on aggregate surface by XPS. The resultshows that the SCA modification has an important influence on the formation ofaggregates-cement paste interfacial transition zone; no chemical shifts of crystal cementhydration products element is produced.