APPLICATION OF AGGREGATES OF NEPHELINE BEARING ROCKS IN INCREASED CORROSION RESISTANCE CONCRETE

.  Diffusion of aggressive components of the external environment deeper into the concrete intensively flows through the contact surfaces and between the filler and the cement matrix. Therefore, it is better to apply active fillers that interact with the cement matrix on certain mechanisms for reducing the conductivity of the contact surfaces, which leads to the products durability.Materials and methods.  Methods of mechanical testing, x-ray phase analysis, scanning electron microscopy were used for comparative studies of concrete corrosion resistance with the active filler (urtite) and with the inactive one (quartz sand).Results.  This research indicates that the urtite filler significantly increases the strength and corrosion resistance of concrete in comparison with the traditional filler with quartz sand. The investigation of the contact zone of cement stone-aggregate with the usage of REM demonstrates that there are no corrosion products in the contact zone of urtite with the cement matrix, while the contact zone of quartz sand and its surface acquires corrosion products represented mainly by gypsum.Discussion and conclusion.  The increased corrosion resistance of the fine aggregate concrete through the application of active filler on the basis of urtite provides lower conductivity of the contact surfaces between cement matrix and filler due to the chemical affinity of the rock-forming minerals of nepheline to calcium hydroxide. The additional factor that enhances the self-inhibition of acid corrosion is the formation of the gel-like layer of silica on the surface of nepheline, which inhibits the advancement of hydroxide ions due to the flow of electro-surface processes. Thus, the nepilnameciais fillers are appropriate to apply in concrete, which is used in the conditions of the chemical aggression of high intensity.