Browsing by Author "Osmanoglu, Faruk"
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Article Evaluating Sustainable Colored Mortars Reinforced With Fly Ash: a Comprehensive Study on Physical and Mechanical Properties Under High-Temperature Exposure(Mdpi, 2024) Akbulut, Zehra Funda; Guler, Soner; Osmanoglu, Faruk; Kivanc, Mehmet Riza; Khan, MehranThis research primarily delves into a comprehensive investigation concerning the synergistic effects of fly ash (FA) with yellow pigment (YP) and red pigment (RP) in the workability, physical characteristics, and mechanical properties of colored mortars, both pre-and post-exposure to high temperatures. Within the experimental design, FA was employed as a 20% substitute for cement, while YP and RP were systematically incorporated into the cement mixtures at varying concentrations (1%, 3%, and 5% by weight). The specimens underwent controlled exposure to high temperatures, ranging from 300 degrees C to 800 degrees C. This study's outcomes unveiled that while the introduction of FA positively influenced mortar workability, including YP and RP adversely impacted spreading diameters (SD), resulting in a discernible reduction in overall workability. Despite these effects, FA emerged as a pivotal factor to enhancing the residual compressive strength (RCS) and residual flexural strength (RFS) of the colored mortars. For instance, after 90 days at 800 degrees C, the control concrete (R0) exhibited a notable 66.13% decrease in RCS, and the sample solely incorporating FA (R1) demonstrated a reduced reduction of 55.39%. Similarly, mortars with YP additives (R2-R4) and RP additives (R5-R7) showcased RCS reductions within the range of 53.32% to 55.12% and 54.51% to 56.04%, respectively.Article Exploring the Flowability, Physical, and Mechanical Properties of Eco-Friendly Colored Cement Mortars With Metakaolin Under Sulfuric (H 2 So 4 ) and Nitric Acid (Hno 3 ) Attacks(Elsevier, 2024) Akbulut, Zehra Funda; Guler, Soner; Osmanoglu, Faruk; Kivanc, Mehmet Riza; Ashour, AshrafThis article aims to investigate the flowability, physical, mechanical, and durability properties of metakaolin (MK) -added colored cement mortars exposed to the effects of H 2 SO 4 sulfuric acid (SA) and HNO 3 nitric acid (NA). MK was used in 20 % replacement with cement, and yellow (YP) and red pigments (RP) were added to the mixtures at 1 % and 3 % of the cement by weight. According to the results, although MK reduced the workability and, therefore, the flow diameter (FD) of mortars, thanks to the void -filling feature of MK, filling the voids in the microstructure caused the samples ' apparent porosity (AP) and relative dynamic modulus of elasticity (RDME) to decrease. Additionally, MK significantly improved the residual compressive (RCS) and residual flexural strengths (RFS) of the samples thanks to the calcium -silicate -hydrate ( C - S - H) bonds it formed in the interior structure, owing to its high pozzolanic efficiency. Moreover, this improvement of MK is more remarkable in samples that remain subject to SA and NA attacks for more time. Furthermore, while YP reduces the workability of mortars and, therefore, the FD value due to its needle -tipped grain structure, RP increases the FD value of the mortars with its spherical grain structure. However, YP and RP contributed to reducing the AP of the samples and increasing RCS and RFS capacities at a meager rate by showing a micro -filling effect. In addition, there were significant increases in the total color changes ( Delta E) of YP and RP -added colored mortar samples, especially after longer SA and NA attacks.