This article presents the effect of aluminum nanoxide on the physical, strength and structural properties of cement mortars. The mortars were made with a water to binder ratio of 0.5 and a binder to sand ratio of 1:3; and 1%, 2%, 3% and 4% of aluminum nanoxide, respectively, were used by cement weight. First, the consistency of nano-Al₂O₃ mortars was tested. Next, after 7 days of sample maturation, compressive and flexural strength tests were carried out and continued after 28 and 90 days of the maturing of the mortars. The best test results were obtained for mortars with the addition of 1% aluminum nanoxide, the compressive strength of which increased by about 20% compared to the reference mortars. The water absorption and rising capillary tests as well as SEM observations were also performed. Another aim of the article is the analysis of the fracture morphology of nano-Al₂O₃ modified mortars. It is assumed that a change of the microstructure of the hardened cement paste affects not only the properties of the modified mortars but also the roughness of the fractures formed as a result of the destruction of the surface. Roughness analysis was performed with methods and tools relevant to fractal geometry. The fractographic analysis showed a significant influence of the modifier in the form of nano-Al₂O₃ on the values of fractal dimensions. The lowest values of the fractal dimension D and the fractal dimension of the D_RP roughness profile of the fracture surface profile lines were obtained for nano-Al₂O₃ modified mortars. The conducted research proved the fractal dimension to be a parameter extremely sensitive to modifications of mortar composition as well as changes related to the maturation time.

This study investigates the effect of nano-SiO₂ on the mechanical properties and fracture surface morphology of cement composites. The focus was on fracture toughness (K_Ic^S) and compressive strength. Composites with nano-SiO₂ showed up to 63% higher fracture toughness and 68% higher compressive strength than unmodified ones. The influence of nano-SiO₂ content (0.09–2.91% by binder mass) and water-to-binder ratio (0.43–0.57) was examined using a Central Composite Design. Properties improved with higher nano-SiO₂ content and lower w/b ratio. Fractographic analysis using laser profilometry revealed a clear correlation between the fractal dimension (D) of fracture surfaces and K_Ic^S and fcm. Lower D values indicated smoother fracture surfaces and denser microstructures. The results clearly show that changes in the composition—particularly the nano-SiO₂ content and the water-to-binder ratio—determine the development of the microstructure, which in turn governs the mechanical properties of the material. Consequently, the study establishes a coherent, quantitative relationship between mixture composition, fracture microstructure, and the macroscopic properties of the composite.

Celem pracy była ocena wpływu nanokrzemionki(NS) na wytrzymałość na ściskanie kompozytów o matrycy cementowejw różnych okresach dojrzewania. Analizowano kompozytyz dodatkiem NS w ilości 0,5 i 2,5% masy spoiwa, przy dwóch stosunkachwodno-spoiwowych (w/s = 0,45 i 0,55). Próby poddanobadaniu wytrzymałości na ściskanie po 3, 7, 28, 90 i 180 dniach.Wyniki badań wykazały, że modyfikacja kompozytów cementowychnanokrzemionką prowadzi do wzrostu ich wytrzymałościna ściskanie w porównaniu do wzorcowych, niemodyfikowanycho takim samym stosunku wodno-spoiwowym. Najwyższąwytrzymałość na ściskanie po 28 dniach dojrzewania, wynoszącą60 MPa uzyskano dla zaprawy zawierającej 2,5% nanokrzemionkiprzy stosunku w/s = 0,45, co stanowiło wzrost tej wytrzymałościw stosunku do zaprawy niemodyfikowanej o 40%. Otrzymanewyniki wskazują, że zastosowanie nanokrzemionki w ilości 2,5%w stosunku do masy spoiwa, w tego rodzaju kompozytach o matrycycementowej, pozwala uzyskać znaczącą poprawę ich wytrzymałościna ściskanie. Szczególnie zauważalna poprawa byłaprzy niższym stosunku wodno-spoiwowym

This paper presents the results of tests on concrete modified with waste powder from the production of epoxy powder coating, planned using design of experiment’s (DOE) experimental design methods. The scope of the investigation included detailed identification of the waste itself (TG/DTA, FTIR, SEM + EDS, laser diffraction), as well as evaluation of selected properties of concretes containing this waste, including compressive strength, density, and durability parameters such as frost resistance and chemical resistance. The scope of the experiment was defined by varying modifier content in the range of 4 to 11% of the cement mass and a water-cement ratio between 0.44 and 0.56. The concrete mixes obtained were characterized by good workability, fluidity, and consistency stability over time, despite the use of the modifier as an additional component in the concrete mix. No adverse effect of the waste used on the durability of the concrete was observed. Concretes modified with waste from the production of epoxy powder coating achieved a frost resistance class of F150 and showed good resistance to chemically aggressive environments (sulfates and chlorides). No products indicating adverse reactions between waste powder and reagents were found. The use of the DOE approach made it possible to determine, in the form of functional relationships, the influence of the modifier content depending on the water-cement ratio (w/c) of the concrete on its compressive strength and density. In general, a decrease in the compressive strength of concrete containing a waste powder modifier was observed, ranging from approximately 11% to 26% compared to unmodified concrete. However, the trend of decreasing compressive strength was reduced as the water-cement ratio of concrete decreased. At a water-cement ratio (w/c) of 0.443, no further decrease in compressive strength was observed. Concrete with 11% waste powder and a w/c ratio of 0.443 achieved 4.7% higher compressive strength than unmodified concrete with the same water-cement ratio. A beneficial interaction was found between a carboxylate-based plasticizer and the waste powder from the production of epoxy powder coatings. The proposed method of using waste as a concrete component is promising and may contribute to reducing the problem of waste management, as well as greenhouse gas emissions.