Research into the properties of concrete modified with natural zeolite addition

•Zeolites are among the most promising of concrete components in the development of new building materials.•Replacement of cement with natural can be increased concrete density, compressive strength, freeze-thaw resistance.•Natural zeolite can be used for modification of cementitious systems.

Concrete mixture used for the tests consisted of cement CEM I 42.5 R, natural zeolite (clinoptilolite), 0/4 fr. sand as fine aggregate, and 4/16 fr. gravel as coarse aggregate. Active components of the zeolite were determined by means of X-ray diffraction analysis, particle form (plate-shaped) and size (11.82 μm) were determined by means of SEM. 5 batches of specimens were made with zeolite content ranging from 0 to 10% (the binding material was substituted with natural zeolite). The following parameters of modified concrete were tested: compressive strength, water absorption, density, ultrasonic pulse velocity, porosity (open and closed), predicted freeze-thaw resistance. Substitution of up to 10% of cement with natural zeolite increases the compressive strength of concrete by 15%, reduces water absorption 2.3 times, increases density and ultrasonic pulse velocity. Substitution of up to 10% of cement with natural zeolite increases closed porosity and subsequently improved the freeze-thaw resistance of concrete. The predicted freeze-thaw resistance calculations revealed 3.3 times higher resistance of concrete modified with up to 10% of natural zeolite.