Recycling has become increasingly important in recent days, and applicability of by-products such as steel slag and marine life shells to cement concrete or solidified materials for port and harbor structures is often studied. To use a large quantity of by-product’s aggregates is desirable.However, the aggregates such as steel slag often contain metal iron which will be expanded as corrosion develops then often cause damage to structures.
　Modified-sulfur concrete, which is used as binder of by-product’s aggregates, has such good properties as high aggregate content, less water absorption, high strength, high salt resistance and good affinity for living organisms. However, long term durability in seawater of modified-sulfur concrete has not been investigated enough.
　This study shows modified-sulfur concrete’s fundamental properties and applicability to port and harbor structures. In this study, the modified-sulfur concretes are made of industry’s and fishery’s by-products such as steel slag and scallop shells. This paper focuses on initial and early ages’ mechanical properties. The main results are as follows,
　(1) In temperature range between 0℃ and 80℃, as temperature of specimen increases,compressive strength and modulus decrease.
　(2) In temperature range between 0℃ and 40℃, the modified-sulfur concretes show about the same properties as normal concretes.