The effect of curing sytem on mechanical properties of high performance concretes

A type of high cement based concrete, known as Reactive Powder Concrete (RPC), is a distinguished composite with its high, mechanical properties and durability properties. Reactive powder concrete; has very low water/cement ratio and reinforced with steel fibers, is usually produced by mixing hyperplasticizers with cement, silica fume and quartz sand. The quartz, used in the mixture is very fine which leads to minimization of micro spaces in the system.Ultra high performance concretes are generally used in military structures, strategic structures, nuclear power plants, storage areas for nuclear wastes, strengthening of reinforced concrete structures due to their superior properties. They are also promising composites for prefabrication of small and medium size high quality precast elements.Four different types of RPC?s, that have compressive strength values up to 250 MPa, have been produced by using 2 types of steel fiber and silica fume within the scope of this study. These specimens were kept in a humid environment for 16 hours after casting. After demolding, these specimens were placed in an autoclave and cured in 1 MPa, 2 MPa and 3 MPa pressure for 4, 6, 8, 10, 12 and 24 hours. Arbitration specimens cured in 7, 14, 21 and 28 days in standard water curing. After the curing procedure, flexural and compressive strength of all composites were determined. Optimum curing pressure and period are chosen based on test data. The fracture energies of some composites produced within optimum conditions were computed. Also, microstructures of these RPC?s were investigated.