M.Sc. Tezi Görüntüleme
Reactive Powder Concretes (RPC) are new generation concretes with compressive strengths ranging from 200 to 800 MPa, tensile strengths ranging from 25 to 150 MPa, unite weights ranging from 2500-3000 kg/m3 and with fracture energy of 30000 J/m2.Eight mixtures with different amounts of cement, micro silica, aggregate, superplasticizer, and steel fibers were produced throughout the program. The water to cement ratio was kept at a level of 0.22-0.23.
Two types of aggregates as diorite and quartz were used in the study. The maximum size for quartz was 0.6 mm while it was 8 mm for diorite. Beksa-Dramix steel fibers of six mm long and 0.15 mm diameter were used in the production of the mixtures. The aspect ratio for the steel fibers was 40, the tensile strength 1100 MPa, and the specific gravity 7.20 g/cm3, respectively.Flow test was performed on the mixtures right after the mixing process ended up and then the mixture was compacted in the 4x4x16 cm three-gang prismatic steel molds. The specimens were placed in the autoclave right after demolding process at the end of 24 hours. Following a waiting period of 24 hours after autoclaving process, flexural and compression tests were performed on the specimens.
Placement and compaction processes were carried out as to minimize the pores ratio in the specimens. To minimize the water to cement ratio, the components were mixed in dry state for a period of approximately 5 min initially; and then the mixing water was gradually added to the mixture while mixing process going on. The total duration for the mixing process was about 20 min for all mixtures.Producing of RPC without steel fibers seems to be impossible. To produce Reactive Powder Concrete (RPC), a two-hour autoclaving under 4 MPa pressure seems to be compulsory for mixtures containing steel fibers of not less than 3-4%.
Keywords: RPC, Micro silica, Superplasticizer, Steel fiber,Autoclave