Improvement of hydrophysical properties of modified heavy-duty concrete working in severe operating conditions

Requirements for concrete used in the manufacture of structures operating in harsh operating conditions are different from those for concrete used in industrial and civil construction. Such special requirements are primarily due to difficult operating conditions, in particular for tunnel structures. Under the influence of a whole range of aggressive environmental factors, this type of structure is partially or completely destroyed, which in turn reduces their design service life. Therefore, a necessary condition for increasing their durability is the creation of a modified dense concrete structure with improved hydrophysical properties: low rates of water absorption, capillary suction, water resistance and high frost resistance. Currently, there are developments in strengthening and protecting such structures with materials with an increased degree of resistance to aggressive factors, for example, polymer compositions. However, polymer concretes have not found wide distribution due to their scarcity and high cost, so today the main building material in the construction of tunnel structures remains concrete and reinforced concrete. Thus, obtaining heavy concretes operating in harsh conditions with increased performance properties by modifying its structure is an urgent task. Objective: To establish the positive effect of complex modification together with a micro-reinforcing component on the hydrophysical properties of heavy concrete. Object: heavy concrete with a complex modifier (superplasticizer + polymer + metakaolin), reinforced with wollastonite for tunnel structures. Research results: A positive effect of complex modification on the properties of heavy concrete was established by reducing the content of binder (cement) and replacing it with metakaolin, which allows improving the hydrophysical characteristics: water absorption - 1.8%; water resistance grade - W14, with a sufficient margin of safety and frost resistance (F more than 600 cycles), which makes it possible to use this composition in practice to obtain building structures with specified characteristics operating under high loads and an aggressive environment, in particular, for tunnel structures.

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