混凝土外加剂对自密实混凝土流动性的影响研究 -土木工程专业

摘要

自密实混凝土（Self-Compacting Concrete, SCC）作为一种高性能混凝土，因其无需振捣即可填充模板并包裹钢筋的特性，在现代建筑工程中具有重要应用价值。然而，SCC的流动性是其性能的核心指标之一，直接影响施工效率和工程质量。本研究旨在探讨不同种类和掺量的混凝土外加剂对SCC流动性的影响规律，以优化其配制方案并提升工程适用性。研究采用试验与理论分析相结合的方法，选取聚羧酸系减水剂、引气剂及纤维素醚等典型外加剂，通过调整其掺量设计多组对比试验，并利用坍落扩展度、T形仪测试及L型箱测试等手段评估SCC的流动性表现。结果表明，聚羧酸系减水剂在适量范围内可显著提高SCC的流动性，但过量掺入会导致离析和泌水现象；引气剂虽能改善抗分离性，但会略微降低流动性；纤维素醚则通过增加粘度间接影响流动性，需谨慎控制掺量。本研究创新性地揭示了多种外加剂协同作用下的流动性调控机制，为实际工程中SCC的配制提供了科学依据和技术支持，同时为后续相关研究奠定了基础。

关键词：自密实混凝土；流动性；聚羧酸系减水剂；引气剂；纤维素醚

ABSTRACT

Self-compacting concrete (SCC), as a type of high-performance concrete, plays an important role in modern construction engineering due to its ability to fill formworks and encapsulate reinforcements without vibration. However, the fluidity of SCC is one of its core performance indicators, directly affecting construction efficiency and engineering quality. This study aims to investigate the influence patterns of different types and dosages of concrete admixtures on the fluidity of SCC, with the goal of optimizing its formulation and enhancing its applicability in engineering. A combination of experimental and theoretical analytical methods was employed, selecting typical admixtures such as polycarboxylate superplasticizers, air-entraining agents, and cellulose ethers. Multiple comparative experiments were designed by adjusting their dosages, and the fluidity performance of SCC was evaluated using tests such as slump flow, T-shaped instrument, and L-box. The results indicate that polycarboxylate superplasticizers can significantly improve the fluidity of SCC within an appropriate dosage range; however, excessive dosage may lead to segregation and bleeding phenomena. Air-entraining agents, while improving resistance to separation, slightly reduce fluidity. Cellulose ethers indirectly affect fluidity by increasing viscosity, requiring careful control of dosage. This study innovatively reveals the fluidity regulation mechanism under the synergistic effects of multiple admixtures, providing scientific evidence and technical support for the formulation of SCC in practical engineering applications, and laying a foundation for subsequent related research.

Keywords: Self-Compacting Concrete; Fluidity; Polycarboxylate Superplasticizer; Air-Entraining Agent; Cellulose Ether

第1章绪论 1

1.1 自密实混凝土流动性研究背景与意义 1

1.2 混凝土外加剂对流动性影响的研究现状 1

1.3 本文研究方法与技术路线 2

第2章混凝土外加剂的基本特性分析 3

2.1 外加剂的分类及其功能概述 3

2.2 减水剂对混凝土流动性的作用机制 3

2.3 引气剂对自密实混凝土的影响分析 4

2.4 其他功能性外加剂的作用探讨 4

第3章自密实混凝土流动性的关键影响因素 6

3.1 流动性与粘聚性之间的关系 6