Since 1900's, well cementing is one of the most substantial method in casing application of oil, gas and geothermal. The American Petroleum Institute (API) identifies well cements in 8 classes with respect to pressure, temperature and the depth of the well. G class cement is the most commonly used cement type for well casing purpose due to its sulphate resistance ability. High sulphate-resistant (HSR) G class cements are often used in well cementing industry. API Standards mainly focus on uniaxial compressive strength (UCS) value of cements cured for 8 and 24 hours. There is no any available research on the long term (14 days) properties of G class cement in the literature. This study presents the comparison of UCS and Elastic modulus (E) growth of 3 different G class cements (2 domestic, 1 foreign products) over 14 days curing time. During the laboratory studies, samples prepared in the laboratory conditions with different curing times (2, 7 and 14 days) are tested based on ASTM standards. It is concluded that the increase in the curing time improves the UCS and E of cements 2-3 times. Logarithmic relationships exist between curing time and UCS, E. Moreover, mechanical properties of these products show significant differences between each other. The UCS and E values of G class cement produced in Turkey have values incontrovertibly lower than that of an equivalent foreign product.