Concrete retarders could efficiently extend the hydration time of cement and maintain the plasticity of concrete slurry. However, some inherent shortcomings, such as a short setting time and poor compatibility, severely limits their application. To solve these problems, in this work, a series of carboxyl-terminated hyperbranched polymers (CTHP) were controllably synthesized and their retarding effects on the concrete setting were investigated. The results showed that the final setting time of concrete was increased by nearly 4 times as the addition amount of third generation CTHP was 1.5%, demonstrating an excellent retarding effect. Furthermore, the compressive strength was increased by 43% after 7 d of curing. The results of resistivity and Zeta potential demonstrated that CTHP could change the surface charge density of cement particles and affect the flocculation of cement particles and thus extend the retarding time. The results of Tg、XRD and SEM demonstrated that the CTHP could induce a decrease in the content of Ca(OH)₂ and an increase in the content of ettringaite (AFt) during the hydration procedure, drastically enhancing the strength of the concrete. These CTHP would demonstrate the enormous potential to commercial concrete for the rapid demand in the engineering field.

混凝土缓凝剂可以有效地延长水泥的水化时间，并保持水泥浆的可塑性。但是，一些固有的缺点，例如设置时间短和兼容性差，严重限制了它们的应用。为了解决这些问题，在这项工作中，可控制地合成了一系列羧基端基的超支化聚合物（CTHP），并研究了它们对混凝土凝结的阻滞作用。结果表明，第三代CTHP的添加量为1.5％时，混凝土的最终凝固时间增加了近4倍，显示出优异的阻滞效果。此外，固化7天后，抗压强度提高了43％。电阻率和Zeta电位的结果表明，CTHP可以改变水泥颗粒的表面电荷密度，影响水泥颗粒的絮凝，从而延长了延迟时间。Tg，XRD和SEM的结果表明，CTHP可以诱导Ca（OH）含量的降低。_{如图2所示，}并且在水合过程中增加了钙矾石（AFt）的含量，从而极大地提高了混凝土的强度。这些CTHP将展示出在工程领域中快速需求的商业混凝土的巨大潜力。