Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: 27. Vladimir Corobceanu, Daniel Covatariu, Rãzvan Giuşcã
Editorial: World Journal of Engineering, 2, p.38 –, 2005.
High strength concretes, without which initially stressed members and high-rise buildings are inconceivable today, are achieved with great technology and economic efforts. From serious technical parameters contributing to this desideratum, the main ones refer to the quality and dosage of cement types and nature of aggregate surface, as well as to concrete preparing, placing and subsequent curing. In numerous situations the high strength concretes are used to create precast members; in order to accelerate the hardening of this material, in most countries, worldwide, thermal procedures are being used. Besides the beneficial effect of intensifying the chemical reactions in the water cement system, with immediate consequences for the hardening kinetics, temperature rise also induces major, destructive modifications in the hardened concrete structure. As a consequence, thermally treated concretes usually exhibit, at over 28 days’ age, strength and durability coefficients which are sensibly lower than in the concretes hardened under normal conditions. At the same time, even at normal temperatures, the cement binding energy is insufficiently used, and the effect is the more remarkable when the binder batching is higher.
The authors propose a technology of high strength concrete preparing and thermal treating, which allows for the optimal use of the cement quantity introduced in the mixture, and concomitantly severely limiting the destructive effects in concrete structures, at high temperatures.
Cuvinte cheie: Concrete, Thermal Treatment, Preheated Components