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    Effect of High-Range Water-Reducing Admixture Chain Lengths on Self-Consolidating Concrete
    (Amer Concrete Inst, 2022) Ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Ramyar, Kambiz
    The effect of the length of main and side chains of high-range water-reducing admixture (HRWRA) on some fresh and hardened properties of self-consolidating concretes (SCCs) was researched. admixtures with different side and main chain lengths were synthesized. For a given SCC slump-flow value, the admixture requirement was the least when the admixture having a medium side chain length (2400 g/mol) was used. Moreover, decreasing the main chain length of the admixture improved the fresh properties' retention of SCC. The fact was attributed to the increase in free polymer in the mixture by increasing the side chain length of the admixture. The main and side chain lengths of the HRWRA admixture were significantly influential on the early compressive strength of SCC mixtures but had a negligible effect on their 7- and 28-day compressive strength and 28-day water absorption.
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    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
    (Ernst & Sohn, 2020) Ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Ramyar, Kambiz
    In 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.
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    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
    (Ernst & Sohn, 2019) Ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Ramyar, Kambiz
    In 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.
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    Effect of nonionic side chain length of polycarboxylate-ether-based high-range water-reducing admixture on properties of cementitious systems
    (Higher Education Press, 2020) ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Ramyar, Kambiz
    Despite the large variations in the behaviors of water-reducing admixtures upon changes in their structures, most previous reports on the cement-admixture compatibility did not provide sufficient information on the structure of the admixture. Hence, the evaluation and generalization of the reports on the cement-admixture compatibility are challenging. in this study, three different polycarboxylate-ether-based water-reducing admixtures with the same free nonionic content, anionic/nonionic molar ratio, and main chain length and different side chain lengths were produced. The compatibility of these admixtures with a CEM I 42.5 R-type cement was investigated. in addition, an analysis of variance was performed on the experiment results to evaluate the contributions of the admixture type, admixture/cement ratio, and elapsing time to the Marsh funnel flow time, mini-slump, slump flow, and compressive strength. The water-reducing admixtures having long or short side chains reduced the initial flow characteristics of the cementitious systems. However, the admixture having the shortest side chain was better with regard to flow retention. The side chain length of the admixture did not have significant effects on the compressive strength and water absorption capacity of the mortar mixtures and mini-slump performances of the cement paste mixtures. Regarding the behaviors of the admixtures in the cementitious systems, an optimal admixture side chain molecular weight is proposed.
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    Effects of anionic monomer type of water-reducing admixture on fresh properties, compressive strength and water adsorption of self-compacting concrete
    (Taylor & Francis Ltd, 2020) Ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Unlu, Ayda; Ramyar, Kambiz
    In 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.
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    Flowability, Strength, and Water Absorption of Mortars Containing Fly Ash and WRA Having Varying Main Chain Lengths
    (Asce-Amer Soc Civil Engineers, 2023) Altun, Muhammet Gokhan; Ozen, Suleyman; Mardani, Ali; Ramyar, Kambiz
    Within the scope of this study, the effect of the main chain length of polycarboxylate-based water-reducing admixture (WRA) on the fresh properties, compressive strength, and water absorption of mortar mixtures containing fly ash was investigated. Three WRAs with the same structure but different main chain lengths and resultantly different molecular weights were used. Effects of the admixtures on the properties of cementitious systems with 0, 15, 30, and 45 wt.% fly ash were investigated. Irrespective of the fly ash substitution level, the fluidity of the mixtures was improved when the admixture main chain length was increased up to a certain level. Possibly beyond a certain main chain length, the entanglement of too large main chains of the polymer to each other reduced the electrostatic effect of the polymer. Thus, the flow properties of the mixtures were affected negatively. The side chain molecular weight (length) of the admixtures was fixed (2,400 g/mol). However, the molecular weight of the admixtures was adjusted as 24, 48, and 71 kg/mol by changing the main chain length of the polymer. The admixture with 48 kg/mol molecular weight showed the best performance in terms of mortar fresh properties. However, the change in the length of the main chain of admixture did not have a considerable effect on the compressive strength and water absorption of the mortar. In addition, apart from the WRA admixture property, time-dependent flow and permeation properties of the mixtures were affected negatively by the increase in fly ash substitution level.
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    Multi-effect of superplasticisers main and side-chain length on cementitious systems with fly ash
    (Ice Publishing, 2022) Ozen, Suleyman; Altun, Muhammet Gokhan; Mardani-Aghabaglou, Ali; Ramyar, Kambiz
    In this study, the effect of main and side chain lengths of polycarboxylate ether-based high-range water-reducing admixtures (WRAs) on the fresh properties, compressive strength and water absorption of cementitious systems containing 0, 15, 30 and 45 wt% fly ash was investigated. For this purpose, three WRAs with the same molecular weight but different chain lengths were produced. According to the test results, the flowability of the paste and mortars was negatively affected when the length of the main and side chains of the admixture was longer or shorter than a certain value. This adverse effect is thought to arise from weakening of the adsorption of the admixture with an increase in its chain lengths. However, when the main and side chain lengths of the admixture were shorter or longer than a certain value, the time-dependent flow properties of the mortar mixtures improved. The main and side chain lengths of the WRAs did not have a significant effect on the compressive strength and water absorption capacity of the mortar mixtures. However, irrespective of the admixture characteristics, with an increase in fly ash substitution, the flow and time-dependent flow properties of the mixtures were negatively affected but their water absorption decreased.
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    Single and Multi Effects of Polycarboxylate Main and Side Chain Lengths on Setting Time, Viscosity, and Yield Stress of Cementitious Mixtures Containing Fly Ash
    (Asce-Amer Soc Civil Engineers, 2023) Altun, Muhammet Gokhan; Ozen, Sueleyman; Karakuzu, Kemal; Mardani, Ali; Ramyar, Kambiz
    In this study, polycarboxylate polymers having different main chain lengths, side chain lengths, and main chain and side-chain lengths at constant molecular weight were synthesized. Cementitious mixtures with 0%, 15%, 30%, and 45% fly ash substitution levels were tested with polycarboxylate based admixtures (PCEs). As the main and side chain length of the PCE increased up to a certain value, regardless of the fly ash content, the fluidity of the mixtures was positively affected. However, after a certain length, both the electrostatic and steric effects of the PCE decreased, as the polymers intercalated and flocculated, adversely affecting the flow properties of the mixtures. Regardless of the PCE structure, the use of fly ash adversely affected the setting times and rheological properties of the mixtures.