River sand (RS) and crushed rock fine (CRF) have been used as fine aggregate in concrete for centuries. However, dredging river beds for RS is now banned in many places due to its adverse environmental impacts. On the other hand, CRF has the major problems of being angular in shape and containing excessive fines. To resolve these problems, the technology of processing CRF to improve the particle shape and reduce the fines content has been developed. Such processed CRF is called manufactured sand (MS). In this research, the particle shape, size distribution, fines content and packing density of MS are studied and the effects of using MS on the performance of concrete are investigated. The results showed that the use of MS can improve the workability of fresh concrete and, if advantage is taken to reduce the water content, can reduce the cement content or increase the strength of hardened concrete. There is, therefore, a high potential for engineering the various properties of MS to enhance the overall performance of concrete.