The paper presents the development of structural lightweight aggregate concrete (LWAC) with density below 1100 kg/m3. It includes the mix design development of self-compacting LWACs with fresh concrete densities in the range of 1000 to 1100 kg/m3 and 28 d compressive cylinder strengths 18-21 MPa. Ordinary commercially available materials were used, and the main measures are a high strength binder consisting of high strength cement, silica fume, fly ash and limestone fines, and lightweight aggregates with high strength/density ratio and particle densities in the range of 300-500 kg/m3. The concretes have been developed without the need of air entraining admixtures, even if fine air voids can be an effective measure to give the low density and good workability. The main reason is that the authors could not find an AEA that gives sufficient stability in the fresh concrete to assure a reliable density. Foaming agents are promising, but more work is needed to establish it as a reliable measure with small enough voids.