This paper presents the applicability of heavy weight concrete (HWC) to port structures, especially to gravity-type concrete structures as caisson. Breakwater, one of the gravity-type concrete structures, needs to be heavy enough to resist external forces by their own weight. Use of filling materials with high density is a general way to increase the weight of the caisson. Another possible way is to apply HWC to the structures. In recent years, new types of concretes using barite and/or artificial heavy weight aggregate (AHWA) have been developed. In this paper, mechanical properties and durability of these new types of HWCs were investigated. Structural performance of RC beams using HWCs was also evaluated through loading tests. One interesting result showed that the fracture energy of concrete using barite (HWC3.4) is approximately 60% lower than that of normal concrete. The mechanical properties of HWC3.4 can be improved by incorporating short fiber. AHWA contains a certain amount of metallic iron so that rust stain due to corrosion of the aggregate appeared on the surface of concrete using AHWA (HWC3.8) when HWC3.8 was exposed to seawater splashing zone. On the contrary, HWC3.8 showed small corrosion content of AHWA when exposed in tidal zone. This result indicates one possibility that HWC3.8 can be applied to the structures serviced in tidal or submerged zone. Loading test results showed that the flexural load capacity of RC beam using HWC can be almost the same as that using normal concrete. RC beam using HWC3.8 showed similar shear carrying capacity to that using normal concrete while that using HWC3.4 was 60-70% of normal concrete. Incorporating short fiber to HWC3.4 is a promising way to improve the shear carrying capacity of the RC beam.