Effect of nonionic side chain length of polycarboxylate-ether-based high-range water-reducing admixture on properties of
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RESEARCH ARTICLE
Effect of nonionic side chain length of polycarboxylateether-based high-range water-reducing admixture on properties of cementitious systems Süleyman ÖZENa, Muhammet Gökhan ALTUNb, Ali MARDANI-AGHABAGLOUb* , Kambiz RAMYARc a
Department of Civil Engineering, Faculty of Engineering and Natural Sciences, Bursa Technical University, Yildirim-Bursa 16330, Turkey b Department of Civil Engineering, Faculty of Engineering, Bursa Uludag University, Nilufer-Bursa 16059, Turkey c Department of Civil Engineering, Faculty of Engineering, Ege University, Bornova-Izmir 35040, Turkey *
Corresponding author. E-mail: [email protected]
© Higher Education Press 2020
ABSTRACT 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 42.5R-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. KEYWORDS
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water-reducing admixture, side chain length, cement paste, fluidity, compressive strength
Introduction
The variety and rate of consumption of concrete chemical admixtures largely increased in the past 40 years. Nowadays, almost all concrete mixtures contain one or more chemical admixtures, some of which affect the cement hydration kinetics. Different types of chemical admixtures are used to modify one or more properties of concrete, particularly its durability [1]. In addition, chemical admixtures are used in special concrete mixtures such as self-compacting concrete, high-performance concrete, underwater concrete, and shotcrete [2]. High-range water-reducing (HRWR) admixtures are the Article history: Received Jul 29, 2019; Accepted Jan 10, 2020
most commonly used chemical admixtures in concrete. For given consistency, these admixtures considerably reduce the water re
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