Browsing by Author "Ramyar, Kambiz"
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Publication Adsorption properties of polycarboxylate ether-based high range water reducing admixture on cementitious systems: A review(Elsevier, 2021-11-05) Karakuzu, Kemal; Kobya, Veysel; Mardani-Aghabağlou, Ali; Felekoğlu, Burak; Ramyar, Kambiz; Karakuzu, Kemal; Kobya, Veysel; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0002-1023-3962; 0000-0003-0326-5015; C-7860-2015; GBH-3020-2022; FEQ-9214-2022Adsorption of polycarboxylateether-based water-reducing admixtures (PCE) on the cement surface affects many properties of cementitious systems, especially fluidity. One of the most important parameters affecting the adsorption behavior of PCE is the anionic group properties. Therefore, understanding the anionic group properties of PCE is of great importance for cement-admixture compatibility. In this study, the effects of PCE's anionic group variation and cement properties on cement-admixture compatibility, especially adsorption, were reviewed based on the studies conducted in the literature. It was observed that phosphate and organo-silane substituted PCEs at certain rates have a positive influence on the fresh state properties of cementitious systems due to adsorption improvement and sulfate resistance. In addition, the fresh state properties of the cementitious system were negatively affected as the C3A content and the increment in fineness of the cement increased the admixture requirement. It was emphasized that the effect of pozzolan utilization on the adsorption properties of PCE in cementitious systems should be considered. Information was given about the properties of PCE recommended for use in the presence of pozzolan.Item Comparison of recycled glass and recycled concrete aggregates bearing mortar mixtures exposed to high temperature, abrasion and drying(Collage Puplishing, 2018) Beglarigale, Ahsanollah; Yazıcı, Halit; Ramyar, Kambiz; Mardani, Ali Aghabaglou; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; C-7860-2015; AAJ-6415-2021; 57669486700In this study, the effects of recycled glass (RG) and recycled concrete (RC) fine aggregates on the drying-shrinkage, carbonation, high temperature and abrasion resistance of mortar mixtures were investigated comparatively. In addition, durability performance of the mortar mixtures was investigated through micro-structural analysis. For this purpose, 9 different mortar mixtures were prepared by replacing 25, 50, 75 and 100 wt.% of crushed-limestone fine aggregate with recycled glass and recycled concrete aggregates. Except for the abrasion resistance, the RG mixtures showed better durability performance than the control mixture. However, the RC mixtures containing more than 50% recycled aggregate showed lower performance than the control mixture.Item Effect of cement C3A content on properties of cementitious systems containing high-range water-reducing admixture(Asce-Amer Soc Civil Engineers, 2017-08) Felekoğlu, Burak; Ramyar, Kambiz; Mardani, Ali Aghabaglou; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; AAJ-6415-2021; 57669486700The effect of cement tricalcium aluminate (C3A) content on the properties of cement paste, mortar, and concrete mixtures containing high-range water-reducing (HRWR) admixture was investigated. Three commercial Type I cements prepared with the same raw material and same gypsum rock interground with clinker, but with different C3A contents (by changing mixture proportions), were used. The fresh state, rheological properties, and compressive strength of the mixtures were studied. Moreover, X-ray diffraction (XRD) patterns of 6-h-age paste mixtures from each cement were obtained. By reducing the C3A content of the cements, the fresh state, rheological, and consistency retention properties of the mixtures improved; however, the strength of the mixtures at early ages decreased. The difference between strength of the mixtures closed at later ages. The XRD analysis of the pastes revealed the formation of more ettringite in the paste prepared from high C3A content cement.Item Effect of cement fineness on properties of cementitious materials containing high range water reducing admixture(Collage Puplishing, 2017) Son, Arif Emre; Felekoğlu, Burak; Ramyar, Kambiz; Mardani, Ali Aghabaglou; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; AAJ-6415-2021; 57669486700The effect of cement fineness on the fresh state and rheological properties as well as compressive strength of cementitious systems was investigated. A CEM I 42.5R portland cement containing 7.92% C(3)A and sulfate resisting cement containing 3.58% C(3)A were used. The cements were ground to 4 different Blaine finenesses, ranging from 2800 to 4500 cm(2)/g. In the absence of water-reducing admixture, the water requirement of mixtures increased with an increase in the cement fineness. Thus, the fresh state properties of the mixtures were affected negatively. However, surprisingly, a reverse behavior was observed in the mixtures containing water-reducing admixtures, that is, an increase of the cement fineness increased the effectiveness of the admixture; consequently, the fresh state properties of the mixtures were improved. This seems to have been caused from the higher adsorption of the admixture on finer cement grains than on the coarser particles. Moreover, as expected, the strength of the mortar and concrete mixtures increased along with the increase in cement fineness and its C3A content.Publication Effect of main and side chain length change of polycarboxylate-ether-based water-reducing admixtures on the fresh state and mechanical properties of cementitious systems(Wiley-Blackwell, 2020-10) Özen, Süleyman; Ramyar, Kambiz; Altun, Muhammet Gökhan; Mardani-Aghabaglou, Ali; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi /İnşaat Mühendisliği Bölümü; 0000-0002-9345-9907; 0000-0003-0326-5015; C-7860-2015; CBF-4437-2022; 57203431200; 57669486700In this study, the effect of both main and side chain length changes of the admixtures on some properties of cementitious systems were investigated. Three different polycarboxylate-ether-based water-reducing admixtures (WRA) having constant molecular weights and different main and side chain lengths were synthesized. Single type of raw material and carboxylate functional group were used in all WRAs. The molecular weights, free nonionic contents, and anionic/nonionic ratios of the admixtures were kept constant. Test results showed that degree of fluidity was observed in cement paste and mortar mixtures in case the admixture main and side chain length is more or less than a critical value. This negative effect is thought to be due to the weakening of the adsorption ability by the chain length change of the admixtures, the being tendency of polymers to intertwine and the adsorbing of admixture on several cement particles simultaneous. Admixtures having excessive long or short main chain and side chain improved the time-dependent slump-flow retention of the mortar mixtures. The admixtures with short main and side chains had insufficient adsorption ability and the admixture with excessive long main and side chains had the interlacing risk of polymers. In both cases, time-dependent behavior improved because the amount of free admixture in solution increased. The change in the chain lengths of the WRAs affected the 1-day compressive strength of the mortar mixtures.Publication Effects of anionic monomer type of water-reducing admixture on fresh properties, compressive strength and water adsorption of self-compacting concrete(Taylor & Francis, 2020-10-18) Özen, Süleyman; Altun, Muhammet Gökhan; Mardani-Ağhabağlou, Ali; Ünlü, Ayda; Ramyar, Kambiz; Altun, Muhammet Gökhan; Mardani-Ağhabağlou, Ali; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; 0000-0002-9345-9907; C-7860-2015; CBF-4437-2022In this study, the effects of anionic monomer functional group type of the water-reducing admixture (WRA) on the fresh properties and compressive strength of self-compacting concrete (SCC) mixtures were investigated. Nine types of polycarboxylate ether-based high-range WRAs with the same main chains but different anionic monomers linked to the main chain were synthesized and used in different dosages to provide the desired slump-flow value in SSC mixtures. For this motivation, in addition to the control admixture consisted of 100% carboxylate functional group, 5, 10, 20 and 30% of carboxylate functional group was replaced by either phosphate or sulfonate group. Test results revealed that the admixtures containing sulfonate and phosphate anionic monomer improved the fresh properties of SCC mixtures compared to those of the control admixture. However, anionic monomer exchange in the structure of the WRA did not significantly affect the compressive strength and water absorption capacity of the SCC mixtures.Item Microstructural analyses of recycled aggregate-bearing mortar mixture(Amer Concrete, 2016-01-11) Beglarigale, Ahsanollah; Yazıcı, Halit; Ramyar, Kambiz; Ağhabağlou, Ali Mardani; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; AAJ-6415-2021; 57669486700In this study, the effects of recycled glass (RG) and recycled concrete (RC) fine aggregates on acid and sulfate resistance as well as alkali-silica reaction (ASR) expansion of mortar mixture were investigated comparatively. In addition, durability performance of mortar mixtures was supported by microstructural analysis. For this purpose, nine different mortar mixtures were prepared by replacing 25, 50, 75, and 100 wt% of crushed-limestone fine aggregate with recycled aggregates. Except for ASR and acid resistance, the sulfate resistance of mortar mixture improved by using RG aggregate. The performance of mortar in terms of ASR and acid sulfuric resistance increased by increasing RC aggregate replacement level. The ASR expansions in RG mixtures increased by increasing the RG aggregate content up to 100%. The RC mixtures containing more than 50% recycled aggregate, showed better performance than the control mixture in terms of sulfate resistance.Item Performance of steel micro fiber reinforced mortar mixtures containing plain, binary and ternary cementitious systems(College Publishing, 2016) Yüksel, Cihat; Hosseinnezhad, Hojjat; Ramyar, Kambiz; Mardani, Ali Aghabağlou; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; AAJ-6415-2021; 57669486700Steel micro fibers provide strengthening, toughening and durability improvement mechanisms in cementitious composites. However, there is not much data in the literature regarding how the extent of their effectiveness changes depending on the type of matrix being reinforced. For clarifying this point, the influence of a constant volumetric ratio (1%) of 6 mm long steel micro fibers on the performance of 5 mortar mixtures was investigated and were prepared using plain, binary and ternary cementitious systems. A total of 10 mixtures were cast. The mineral admixtures used in the study include silica fume (SF), metakaolin (MK) and a Class C fly ash (FA). While the replacement levels of SF and MK were 10% by weight of the total mass of the binder, this ratio was chosen as 30% for FA. In addition to the behavior of the mixtures under compressive, flexural and impact loads, abrasion, water absorption, chloride ion penetration, freezing-thawing resistance and drying shrinkage characteristics of the mixtures were determined. Test results indicate that generally the refinement in the pore structure of the matrix provided by mineral admixtures and the increase in resistance against growth and coalescence of micro-cracks provided by fibers produce a synergistic effect and improve the investigated performances of the mixtures.Publication Review of research on designing methods and properties of roller compacted concrete mixtures(Pamukkale Üniversitesi, 2020-01-01) Mardani-Ağhabağlou, Ali; Bayqra, Sultan Hüsein; Özen, Süleyman; Altun, Muhammet Gökhan; Faqiri, Zia Ahmad; Ramyar, Kambiz; MARDANİ, ALİ; Bayqra, Sultan Hüsein; Altun, Muhammet Gökhan; Faqiri, Zia Ahmad; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; 0000-0003-2200-2691; AAJ-6415-2021; C-7860-2015; CDR-7456-2022; CBF-4437-2022; COI-3623-2022Roller compacted concrete (RCC) has been widely preferred in the world recently due to its rapid production rate, low cost and good durability compared to those of the traditional concrete. Having different production techniques from conventional concrete, RCC is used in many areas such as factories, oil stations, airports, industrial floor coverings, roads and dams. There are several methods for the proportioning of RCC mixtures, among which maximum density method is the most preferred one. In this study, the methods of designing of RCC mixtures are explained with an emphasis on the maximum density method. In addition, the previous studies on the RCC mixtures designed with the maximum density method are reviewed and suggestions are made for the future researches.Item Transport properties and freeze-thaw resistance of mortar mixtures containing recycled concrete and glass aggregates(Taylor & Francis, 2016-11-15) Beglarigale, Ahsanollah; Yazici, Halit; Ramyar, Kambiz; Mardani-Aghabaglou, Ali; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; AAJ-6415-2021; 57669486700The effects of recycled glass (RG) and recycled concrete (RC) fine aggregates on the compressive strength, ultrasonic pulse velocity, dynamic elastic modulus, transport properties and freeze-thaw resistance of mortar mixture were investigated comparatively. Nine different mortar mixtures were prepared by partial replacement of crushed-limestone fine aggregate with recycled aggregates. Compared to that of the control mixture, the transport properties of RC aggregate-bearing mixtures inversely affected with increasing the replacement level of this aggregate. The opposite results were obtained in RG aggregate-containing mixtures. Frost resistance of mortar mixture improved by using both of the recycled aggregates. Improvement of frost resistance of RC mixtures was attributed to the presence of improved Interfacial transition zone between matrix and coarse aggregate (ITZ) in RC-bearing mixture and to the high number of pores existing in the well-distributed RC aggregates in the mixture. Perhaps, these pores provide additional sites for the water escaped from capillary pores upon ice formation.