Moeinian Mahdi, Ardjmand Mehdi, Nosratinia Ferial
Department of Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran.
Sci Rep. 2024 Aug 30;14(1):20170. doi: 10.1038/s41598-024-71078-y.
The objective of this study focused on the design and preparation of a molecularly modified polycarboxylate superplasticizer to develop concretes with enhanced engineering features. For this purpose, polyethylene glycol was chemically modified with maleic anhydride to give the mono polyethylene glycol maleate (MPEGM). Then, polycarboxylate superplasticizer comprising of isoprenyl oxy polyethylene glycol (TPEG) and acrylic acid (AA, PCE-1), and the synthesized MPEGM with TPEG and AA (PCE-2) were prepared through solution radical polymerization. Subsequently, concrete mixtures with different dosages (0, 0.1, 0.15, 0.2, 0.25, 0.3 wt%) of PCE-1 and PCE-2 were prepared. Chemical structure of the synthesized MPEGM and superplasticizers together with their copolymer composition were identified by FTIR and HNMR analyses. The molecular weights (Mw) and molecular weight distributions (PDI) of PCE-1 (8.74 × 10, 1.36) and PCE-2 (8.74 × 10, 2.19) were studied by GPC analysis, respectively. The zeta potential of cement particles (2.8 mV) becomes negative in the presence of 0.6 g/L of PCE-1 (- 7.8) and PCE-2 (- 9.5). This implies that electrostatic and steric hindrance forces of adsorbed superplasticizers synergistically provide a situation for appropriate dispersion of cement particles. The results of water-reducing percentage, fluidity, air content, bleeding water rate, initial and final setting times, wet density, flexural and compressive properties, and ultrasonic pulse velocity analyses exhibit significant enhancement on the features of concrete mixtures made of polycarboxylate superplasticizer. The superiority of PCE-2 to PCE-1 was connected to its adsorption-dispersibility potent induced by stronger electrostatic and steric repulsion forces, which result in quality and continuity enhancement in concretes.
本研究的目的集中于设计和制备一种分子改性聚羧酸系高效减水剂，以开发具有增强工程特性的混凝土。为此，用马来酸酐对聚乙二醇进行化学改性，得到单聚乙二醇马来酸酯（MPEGM）。然后，通过溶液自由基聚合制备了由异戊烯氧基聚乙二醇（TPEG）和丙烯酸（AA，PCE - 1）组成的聚羧酸系高效减水剂，以及合成的MPEGM与TPEG和AA组成的（PCE - 2）。随后，制备了含有不同剂量（0、0.1、0.15、0.2、0.25、0.3 wt%）PCE - 1和PCE - 2的混凝土混合物。通过傅里叶变换红外光谱（FTIR）和核磁共振氢谱（HNMR）分析确定了合成的MPEGM和高效减水剂的化学结构及其共聚物组成。分别通过凝胶渗透色谱（GPC）分析研究了PCE - 1（8.74×10，1.36）和PCE - 2（8.74×10，2.19）的分子量（Mw）和分子量分布（PDI）。在存在0.6 g/L的PCE - 1（-7.8）和PCE - 2（-9.5）时，水泥颗粒的ζ电位（2.8 mV）变为负值。这意味着吸附的高效减水剂的静电和空间位阻作用力协同为水泥颗粒的适当分散提供了条件。减水率、流动性、含气量、泌水率、初凝和终凝时间、湿密度、抗折和抗压性能以及超声脉冲速度分析的结果表明，聚羧酸系高效减水剂制成的混凝土混合物的性能有显著提高。PCE - 2相对于PCE - 1的优越性与其由更强的静电和空间排斥力诱导的吸附分散能力有关，这导致混凝土质量和连续性的提高。
