PHYSICO-CHEMICAL MODIFICATION OF MONOLITHIC CONCRETE CEMENT SYSTEM
DOI:
https://doi.org/10.15802/stp2015/57103Keywords:
cement system, modification, structure formation, concreteAbstract
Purpose. The paper is aimed to the development of scientific bases of the technology of modified concrete of new generation for special facilities by managing the processes of structure formation of modified cement system in conditions of hardening. Methodology. For the achievement the goal: 1) the research of rheological characteristics of modified concrete mixes for special facilities purpose and processes of structure formation of modified cement system of natural curing concrete was conducted; 2) there were defined methods of reliable evaluation of concrete strength at the removal time of formwork and transmission of loads to the constructions where the concrete has not reached the designed strength. Findings. The author found that the structure formation process develops in the hydrating modified cement system as a result of interaction of various macroions. In this process its active parts prevail, which considerably exceed its dissipative part compared to normal conditions of hardening. Originality. There were established the regularities of structure formation of modified cement system, reinforced with synthesized, well crystallized helical filamentary crystals, mechanical grip of which is considered as a principal source of strength in combination with an additional coupling achieved due to cross-germination of crystals. Practical value. In the study the increased binding capacity of cement in high strength concretes and the use of modified cement systems in the special conditions of concreting were considered. The organo-mineral modifying complex that provides the dispersed reinforcement of concrete cement matrix which allows modifying the process of cement matrix structure formation by changing the nature of the surface of binder and modifier was developed. The temperature factor has no negative influence on the hardening concrete and complex modifier provides the improved physico-mechanical characteristics of cement matrix and concrete by means of the primary changes in the system state. In the modified hydrating cement system as a result of interaction of various macroions the structure-forming process with advantage of active parts, which significantly exceed its dissipative part of the normal conditions of hardening are developing. The results of modeling the behavior of modified hydrating cement system show that fluctuations in the concentration of intermediate hydration products are observed in the system. They are identified with the emergence of spatiotemporal structure.
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