This work aims at studying the performance of crushed sand (CS), resulting from limestone quarries, when partially or completely replaces the natural sand (NS) in mortar. NS is replaced by different ratios with CS to make mortars with three w/c ratios. The tests consist of determining the superplasticizer requirement to have a plastic consistency of mortar according to the CS content. For a given workability, mechanical, and rheological properties of different mortars are tested. It is concluded that CS has a great effect on mortar properties. Its presence enhances the compressive strength, decreases the rheological parameters and reduces the dosage of superplasticizer which becomes very suitable even with low w/c ratio. Then for making mortar with low w/c ratio, it is interesting to use partial replacements of CS than using an excessive dosage of superplasticizer. The CS has a great potential to provide an alternative to NS and helps in maintaining the environmental balance.