CEMENT MATRIX CONTAINING MICRONIZED RECYCLED CONCRETE AND THE INFLUENCE OF ADDITIVES

The article deals with the selection of a suitable additives in cement composite material for the production of a masonry block. The blocks contains recycled concrete which replacing 40% cement. The recyclate comes from concrete drainage gutters. Based on previous measurements, two hardening accelerators and one superplasticizer were selected. To determine the effect of these additives on the recycled cement composite, pairs of samples sets were produced, of which one set contains concrete recyclate and the other one does not contain it. The dynamic modulus of elasticity and the dynamic shear modulus were measured by the resonance method at the age of samples 1, 7, 14, 21 and 28 days, and by an ultrasound method at 28 days of age. Then was measured compressive strength. All values were compared with the values measured on the reference samples