NANOMODIFIED RAPID HARDENING FIBER-REINFORCED CONCRETES

It is shown that one of the innovative ways of obtaining of Rapid-hardening concretes with enhanced performance for fortifications is the use of nanotechnology techniques related to the directed process of structure formation by modifying of nanoscale elements. The problem of improving of the higher-speed impact stability of high-strength concrete by hybrid reinforcement of their structures at the micro level – by energy-active ultrafine mineral additives and macro level – by dispersed fibers is considered. The results of flowablity test of fresh nanomodifed concrete and mechanical and impact tests of nanomodified Rapid hardening fiberreinforced concretes are shown. Ultrafine particles relating to microheterogeneous systems are characterized by high values of specific interfacial area and “excess surface energy” and promote more complete synergic effect of other components activity including increasing of flowability mixtures by polycarboxylates. The packing particles optimizing of Portland cement systems by ultrafine mineral additives and new generation polycarboxylate superplasticizer determines the initial density of system, stimulates nucleation processes in the intergranular space, causes acceleration reactions with formation additional hydrates in unclinker part of the cement matrix, increasing of density of the interfacial contact zone between aggregate and cement stone. The fiber reinforced nanomodified concrete characterized by increased crack resistance at the higher-speed impact action.

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