Zahra Nasirzade - Department of applied chemistry, Faculty of science, shiraz branch, Islamic Azad University, Shiraz, Iran
Hamid Reza Safaei - Department of applied chemistry, Faculty of science, shiraz branch, Islamic Azad University, Shiraz, Iran
Peyman Ghatee - Department of civil Engineer, Faculty of Engineering, shiraz branch, Islamic Azad University, shiraz, Iran
Hassan Nematollahi - Work-overdepartment, SZOGPC, Iran

experimental study has been performed to characterize the early hydration and setting of cement pastes prepared with Class G oil well cement at water-to-cement ratios w/c = 0.35-40%, and mixed with phosphate salt as retarder, cured at 25oC. Chemical shrinkage during hydration was measured by system, degree of hydration was determined by thermo-gravimetric analysis. Setting time was tested by Vicat. A boundary nucleation and growth model provides a good fit to the chemical shrinkage data. Retarder and viscosity modifying agents decrease and less hydration products and delay cement nucleation, causing later setting times

oil well cement; retarder; setting time; phosphate salt