The study investigates effect of the additive consisting of natural zeolite (clinoptilolite) and soda lime glass powder on the hydration, mechanical properties and porosity of Portland cement concrete. The effect of mineral additive on the technological, physical-mechanical properties and porosity of the mortar was investigated by increasing the content of natural zeolite and glass powder added to the mortar up to 20% by weight of cement in increments of 5% and different particles size of natural zeolite. The mixes with the best technological and mechanical properties were identified and further studies were conducted by replacing 10% and 15% of cement with natural zeolite and soda lime glass with an average grain size of 59.3 μm, 29.0 μm or 3.6 μm of zeolite, and 29.6 μm of glass powder. The hydration process and microstructure of hardened cement paste modified with the aforementioned mineral additives was analysed by microcalorimetry, X-ray diffraction tests and thermogravimetric analysis. The optimal composition of cement paste and particle size distribution of natural zeolite were determined to achieve the higher flexural and compressive strength and lower open porosity. The mixture of mineral additives has the highest effect in terms of flexural and compressive strength and open porosity when added at the proportion 75:15:10 (cement:natural zeolite:soda lime glass) and when zeolite with an average particle size of about 3.6 μm is used

This article analyses the combined effect of a mixture of natural zeolite and ground soda lime silicate glass on the durability properties of concrete. The specimens were prepared by replacing 25% of the cement with a mixture of zeolite and glass at different proportions with zeolite particles of two different sizes and cured for 28 and 90 days. Chloride migration, the depth of water penetration under pressure, and freeze–thaw cycle tests were performed, and compressive strength was determined. The combined effect of the mixture on the composition and microstructure of the cement matrix was studied by analysing the results of XRD, TGA, SEM-BSE, and porosity tests. The test results showed that irrespective of the cement “dilution” effect, the mixture of additives had a beneficial combined effect: increased durability of concrete, a denser structure of the cement matrix, the formation of calcium aluminate hydrates, faster rate, and higher degree of hydration.

This research focuses on the impact of a pozzolanic additive (zeolite) on the durability properties of concrete and the evaluation of the surface finish of the final product (concrete). Durability is one of the key characteristics of concrete that ensures the performance of concrete structures, landscaping elements, and products over their lifetime and beyond. To reduce CO₂ emissions, replacing part of traditional cement with pozzolanic additives is necessary. We tested concrete mixes in which up to 20% of cement was replaced with a pozzolanic additive. Concrete flow and entrained air content were measured. The following properties of hardened modified concrete were determined: density, ultrasonic pulse velocity, water absorption, freeze–thaw resistance, and mechanical properties after 7 and 28 days of curing. The compressive strength values were normalised and expressed in MPa/g to obtain a deeper insight into the effect of a pozzolanic additive on the mechanical properties of concrete. The test results showed that the pozzolanic additive selected for testing reduced the flowability, density, and ultrasonic pulse velocity; increased entrained air content; and reduced the porosity of concrete. The compressive strength results at 28 days (normalised and expressed in MPa/g) showed that all specimens modified with up to 20% zeolite had a higher compressive strength than that of the reference specimen (from 0.0138 to 0.0164). Freeze–thaw resistance results showed that 15% was the optimum content of zeolite additive that could replace cement in the mix to obtain concrete with appropriate durability properties. Concrete surface finish evaluation tests showed that 15% of the pozzolanic additive is recommended to obtain a good-quality surface finish of exposed concrete.