Research into the properties of concrete modified with natural zeolite addition

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 mu m) 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. (C) 2016 Elsevier Ltd. All rights reserved.