This paper discusses the effects of an increase in the maximum allowable limestone content of general purpose (GP) cement from 7.5 up to 12%. The substitution of a higher content of clinker with limestone will allow for a lower embodied energy and emissions associated with the manufacture of GP cement. Fresh and hardened properties of normal-grade concrete (N20 and N32) prepared with GP cement containing limestone contents in the range of 5 to 12% were investigated. The compliance of test results were checked and confirmed against the requirements of cement and concrete specifications. In addition, the test results were statistically examined, and no significant change in concrete properties was observed due to the change in limestone content. It is recommended that the allowable limestone content of GP cement be increased from 7.5 to 12%, resulting in an estimated 6% reduction in CO2eq emissions associated with cement manufacture.