The researchers' primary objective was to evaluate the early-strength characteristics of self-compacting concrete (SCC), which is a type of concrete that can be placed without external vibration, even in congested areas. Two unique characteristics of SCC are its high-percentage substitution of cement with fly ash or slag cement, or with both fly ash and slag cement and a relatively high superplasticizer dosage. Both of these characteristics retard early-strength gain. The impetus was to develop SCC with an early strength suitable for precast applications. The major findings are that it is possible to proportion SCC mixtures with high early strength (30 MPa at 16 h under steam curing) and that high slump does not necessarily correlate with self-compaction.